An 'Achilles Heel' in Viral Replication Helps Researchers Develop a Universal Cure for Influenza

Nadège Chéry, PhD

When influenza attacks, it may infect anyone, regardless of his or her age. But when influenza kills, it usually takes the lives of individuals, like the elderly, who are less able to fight back.² In Canada, 6000 deaths are attributable to influenza every year³ with the highest rate of mortality occurring among people over 65 years of age.² Thus, when it comes to older individuals, both early diagnosis, and prevention are imperative. Because the influenza virus continuously changes, strategies for the prevention of flu outbreaks, although thoughtfully planned, have had limited success. Recently, however, scientists have found a "weakness" in influenza's ability to escape traditional flu therapies. This discovery has set the stage for the design of new antiviral drugs which, potentially, may constitute a cure for the flu.

What is Influenza?
Influenza is a member of the Orthomyxoviridae family,1 and causes disease by infecting the epithelial cells that compose the lining of the respiratory tract. Influenza produces symptoms similar to other viruses which infect the respiratory tract. Flu outbreaks are common among elderly persons, particularly in nursing homes.⁴ Since the immune systems of elderly people in a nursing home may be compromised,⁵ their ability to fight an influenza infection can be severely undermined.

Physiologic Vs. Ventricular Pacing--Which is More Appropriate for Your Elderly Patient?

Tawfic Nessim Abu-Zahra, BSc, MSc

Cardiac pacemakers are widely used to treat the symptoms of cerebral hypoperfusion and hemodynamic decompen-sation that are caused by bradycardia.¹ Pacemaker implantation is indicated for diseases of the sino-atrial (SA or sinus) and the atrioventricular (AV) nodes. There are two different modes of cardiac pacing, ventricular and physiologic. Ventricular pacing involves the direct stimulation of the ventricular myocardium without interaction with the atria, whereas physiologic pacing stimulates either the atria alone (atrial pacing) or both the atria and ventricles together (dual pacing).

There are many theoretical reasons why physiologic pacing should be superior to ventricular pacing. Physiologic pacing maintains the synchrony of atrial and ventricular contraction and the dominance of the sinus node by stimulating both the atria and ventricles.² Physiologic pacing may prevent the pacemaker syndrome--a collection of symptoms associated with the asynchronous contraction of the heart that occurs with ventricular pacing.² In comparison to ventricular pacemakers, however, physiologic pacemakers are more expensive, and are more difficult to monitor.³

Despite the theoretical advantages of physiologic pacemakers, this mode of pacing is not widely used.

Doctor Beware! A Patient's Retained Licence Can Cause the Loss of Yours

Tracey Tremayne-Lloyd and Lonny J. Rosen
Tremayne-Lloyd Partners
Toronto, Ontario

Physicians who treat elderly patients are well aware of how important a driver's licence is to a geriatric patient. The ability to drive represents perhaps the greatest source of independence to an elderly patient. The driver's licence ensures that he can maintain an active lifestyle, keeps up his social interaction and family ties, and that he has the ability to seek support or treatment for his ailments. All of these support systems are crucial to the health and wellbeing of an elderly patient, particularly as his health begins to fail. For this reason, it is particularly difficult for a family physician to contact her local Ministry of Transportation office and report that a patient has become medically unfit to drive. However, in most Canadian provinces, it is the physician's legal obligation to report any patient who has become unfit to drive, even when that report will result in the patient losing his driver's licence and all of its attendant benefits (especially the patient's independence). It is important to remember that while it is the Ministry, and not you the doctor, who will determine whether a patient's licence should be revoked, it is your licence to practice that may be jeopardized if you fail to make the required report.

Michael A. Gardam MSc, MD, CM, FRCPC
Medical Director, Tuberculosis Clinic
Associate Hospital Epidemiologist
University Health Network

What is a Skin Test and How is it Administered?
Tuberculin skin testing is the most established method of diagnosing tuberculosis infection, that is both active disease and asymptomatic latent infection. Different skin testing techniques have been developed over the past 70 years. The Mantoux test, however, is the standard procedure in North America. The Mantoux test involves the intradermal injection of 0.1 ml of purified protein derivative (PPD--a precipitate prepared from filtered heat-sterilized cultures of Mycobacterium tuberculosis). The only absolute contraindication to administering the test is a history of anaphylaxis induced by any of the components. Those with a history of BCG vaccination may be skin tested.

The test is usually administered in an area that is free of blood vessels, hair or edema, on the flexor surface of the forearm, but it may also be administered on the upper chest or back. The needle should be inserted just under the skin with the bevel facing up until the bevel is fully inserted. A bleb should be raised when the PPD is injected. If this is not accomplished, or the PPD leaks out onto the skin, the test should be readministered in a different site. The test must be read at 48 to 72 hours by a trained healthcare professional.

By Age 70 Men Lose Bone Mass at the Same Rate as Women

Valerie Serre, PharmD, PhD

Aging of the population is associated with the rising incidence of age-related conditions such as osteoporosis. In the US, as many as 41 million people could develop osteoporosis by 2015. Osteoporosis is a progressive microarchitectural deterioration of bone tissue, which induces skeletal fragility predisposing bone to fracture. This disease is mostly known to affect postmenopausal women. Osteoporosis in men has sparked interest because of the worrisome finding that 20% of people with osteoporosis are men. Men reach peak bone mass in their late 20s. The decline in bone mass becomes apparent in men in their 40s and by the age of 70 both men and women display an identical rate of bone loss. If left untreated, osteoporosis brings about complications such as pain, decreased quality of life, dependence, and fractures. These fractures are located mainly at the hip, vertebral wedge and wrist and are often associated with mortality. The dollar cost of this silent epidemic is enormous (over 10 billion US dollars per year in the United States), and it is likely to increase exponentially in the near future.

A Fragile Future for Men

Gradual Immunologic Decline Explains Frequency of Herpes Zoster Among the Elderly

John M Conly, MD,CCFP, FRCPC, FACP
Consultant, Infectious Diseases
Director, Infection Prevention and Control
University Health Network (Toronto General,
Toronto Western and Princess Margaret Hospitals)
Professor of Medicine, University of Toronto

Introduction
Although it is now understood that varicella-zoster virus (VZV) is the etiologic agent for both varicella and herpes zoster, it is of historical interest to note that in the early medical literature, the clinical illnesses of varicella and herpes zoster were considered separate entities. Just six decades ago it was still taught at Harvard University that these viruses were unrelated.¹ In 1943, a pediatrician named Garland suggested that zoster may be due to the reactivation of a latent varicella virus,2 but it was not until 1958 that VZV was definitively recognized as the etiologic agent for both varicella and zoster.^3,4 The VZ virus is a DNA virus and is a member of the Herpesviridae family bearing many distinct similarities to other members of this group of viruses. The virus is spread by direct contact, by droplet and airborne routes from vesicular fluid of skin lesions, or from secretions from the respiratory tract.⁵ Transplacental transmission has also been documented.

Vaccination Curtails Influenza Outbreaks, but Side Effects are Still Possible

Dr. Allison McGeer MSc, MD FRCPC
Director,
Infectious Control,
Mount Sinai Hospital,
Toronto, ON

Every year, approximately one in six Canadians are infected with influenza. Healthy adults infected with influenza miss, on average, 2-7 days of work, and have a 10-30% chance of being prescribed a course of antibiotics. Influenza causes approximately 20% of all cases of acute otitis media in children,¹ and is the most common single infectious cause of hospital admission in young children.^2-4 However, the greatest impact of influenza is seen in the elderly. Every year, nearly 1% of older adults with any chronic underlying illness require hospital admission due to influenza, and about 4000 die from influenza and its complications.⁵

Vaccination is the only effective method for the prevention of influenza. Annual vaccination is required because influenza viruses are able to mutate their antigenic coat continuously in order to evade the human immune system (see "Chasing Away the Flu Bug" on page 20 for a more detailed description of this process).

The Elderly Display a Weaker Vaccine-Triggered Immune Response

Janet E. McElhaney, MD
Associate Professor, Division of Geriatrics,
Glennan Center for Geriatrics and Gerontology

Introduction
Pneumonia and influenza together have been identified as a leading cause of catastrophic disability and the fourth leading cause of death in the age 65 and over population. The fact that older people have an increased risk of contracting influenza and/or pneumococcal disease is to a large extent due to the combination of immuno-senescence and chronic diseases affecting 80 to 90% of the over 65 population. The aging process results in a decline in immunity that largely affects T-cell-mediated defense mechanisms. In older people, this decline is associated with an increased risk of viral infections, particularly influenza. Humoral immunity may also diminish with aging but to a lesser degree, perhaps due to the T-cell function that regulates the production of antibodies. Due to their ability to stimulate the aging immune system, influenza and pneumococcal vaccinations are by far the most cost-effective medical interventions when it comes to older adults.

Impact of Influenza and Pneumococcal Infections
The association between advanced age and the risk of serious influenza infections is one of the most well-documented examples of the potential effects of immunosenescence.

Brian Conway, MD, FRCPC
Staff Physician,
Centre for Excellence HIV/AIDS,
Assistant Professor, Pharmacology & Therapeutics,
University of British Columbia

Recently, the bulk of media attention has fallen on the global HIV pandemic, and on the impact it is having in Africa. In North America, although AIDS is still predominantly a disease of young adults, an aging but relatively healthy population of HIV positive individuals is slowly becoming a cohort of HIV positive elderly. A review of recent medical literature reveals few, if any, articles that deal with AIDS in elderly patients. The absence of research in this field will mean a medical community that is unprepared to treat and diagnose HIV in an older population. Consequently, elderly patients may not receive the degree of care and attention that they deserve. At Geriatrics & Aging, we strive to cover the latest medical developments and issues, even those that may be somewhat controversial. This month we are proud to present an article contributed by Dr. Brian Conway, an international leader in the field of HIV research, on how HIV is 'moving up the age ladder'.

Introduction
Although it may be assumed that the HIV epidemic is waning, it must be remembered that by the end of 1999 there were still over 33 million adults and children living with HIV/AIDS throughout the world.¹ Of these, the vast majority (32.4 million or so) are adults. In the United States, there are over 400,000 adults/adolescents living with this disease.

Brian E. Maki, PhD, PEng

Tai Chi has been shown to increase balance confidence and reduce risk of falling in elderly patients.1 Although direct effects on balance control have yet to be demonstrated, it seems likely that Tai Chi may improve the ability to control balance by training the mind and body to integrate balance-related sensory information and by helping an individual to develop a greater "awareness" of both body position and limits to stability. By requiring a series of movements that involve lateral weight transfer and narrowing of the base of support, Tai Chi may bring about specific benefits with respect to control of lateral stability and the consequent capacity to avoid lateral falls, which are the ones that are most likely to result in debilitating (and life-threatening) hip-fracture injuries. Tai Chi has a number of other positive features that may facilitate adherence to a program: it requires no special equipment, it is enjoyable to most participants, it can be performed either in social settings or at home, and it can be safely tailored to match the physical abilities of the individual.

Notwithstanding the above, it is likely that there is nothing "magical" about Tai Chi per se. It would seem that the key factor is developing an exercise program that trains balance, as opposed to strength, flexibility or endurance alone, and incorporating into the balance training a wide range of movements that allow the limits of anteroposterior and lateral stability to be challenged in a safe, enjoyable and convenient manner.

To be linked to a community program that may include Tai Chi please contact the Falls Prevention Program at Sunnybrook Hospital.

References

1. Wolf SL, Barnhart HX, Ellison GL, Coogler CE. The effect of tai chi quan and computerized balance training on postural stability in older subjects. Phys Ther 1997; 77:371-381.

Typically, the practice of Tai Chi requires the performance of a series of movements (comprising one 'form') which involve the shifting of weight from one leg to another in bent knee positions, accompanied by coordinated arm movements, and which must culminate in a final, well-balanced stance maintained for a brief period of several seconds.
In 1980, a book illustrating the 88 'forms' of Taijiquan (Tai Chi) reported the findings of an investigation carried out by the Beijing Sports Medical Research Centre on 88 elderly individuals ranging from 50 to 89 years of age. Group A, comprised of 32 regular practitioners of Taichi, had scores dramatically superior to Group B, the control group, in tests designed to asses cardiovascular function, including blood pressure and rate of arteriosclerosis (cardiographs confirmed the tests), spinal deformity, osteomalacia, and flexibility and range of movement. In Tai Chi, the waist is kept relaxed, the spine erect, and the body is held straight. Consequently, regular practice strengthens the spinal column, reinforcing postural balance and preserving strength and flexibility at the waist.

Source: Taijiquan in 88 Forms (5th ed.), Hai Feng Publishing Company, Hong Kong, 1988.