Body Shop: Need Some Vessels for Your Liver

Anna Liachenko, MSc
Managing Editor
Geriatrics & Aging

Despite the recent progress with transgenic pigs and tissue engineering, we are still in serious need of both functional and immuno-compatible organs, especially such complex organs as the liver, kidney and heart. Until recently, the artificial creation of complex organs seemed an unobtainable goal, mostly due to the challenge of providing them with proper vascular support. Recently, Joseph Vacanti and his colleagues created an artificial vascular system--a 'circulatory-system-on-a-chip'--that may soon solve the problem.

In organ engineering, living cells are first grown in the lab on scaffolds of biodegradable plastic, where they spontaneously arrange into functional tissues. Once the plastic template is degraded and the newly formed organ is implanted, the body's vascular system grows in. This approach has made available lab-grown replacements of both skin and cartilage, but has not yet been successful for the development of a more complex organ. The challenge is that the body's blood vessels do not grow fast enough to sustain thick tissues, and the inside part of the artificial organ dies before it can obtain the nutrients and oxygen necessary for its continued survival.

Vacanti's group proposed a solution to this problem by making an artificial vascular network, which will then be combined with other artificially grown tissues, to yield a complete organ. Early attempts at mimicking vascular support for the lung and liver revealed two problems: poor blood flow, and a shortage of the capillaries that are so necessary to ensure adequate nutrition for the tissue. The system is being re-designed to deliver blood at pressures at which it would normally be received by the given organ, and by quadrupling the number of capillaries. When this phase is complete, the researchers will tackle the issue of converting the paper-thin, vascular sheets into complete organs. The task is challenging given that several hundred square feet of vascular tissue, or about 7,000 of the 4-inch wafers, are needed to match the blood-cleansing power of an adult liver. These will have to be merged into a 3-D network complete with hepatocytes and fibroblasts. Three main approaches have been proposed--'stack", "jelly roll", and 3-D scaffolds. In the "stack" approach, sheets with various cell types are alternated and stacked on top of each other. In the "jelly roll", sheets are laid side by side and are then rolled together. In 3-D scaffolds, a biodegradable polymer guides the growth of the blood vessels. All three approaches will be investigated with respect to their ability to provide blood to the organ tissues.

While Vacanti's group is currently the closest to creating vascular support for artificial organs, Michael Sefton, a tissue engineer at the University of Toronto, is investigating other options. "Our goal is similar to that of Joseph Vacanti, except that our approach is based on exploring the principles of angiogenesis, which is a natural process of growing blood vessels, by adding growth factors or other factors," he says. Sefton & Vacanti are currently collaborating on a project called the 'Life Initiative,' which is a 'multi-institutional and multi-national project to grow large organs.

Just think, in a couple of years you may be able to get an artificial liver or heart via the Internet!

Live Wealthy and Healthy

Next time you wonder why your Uncle Bob smoked, drank, and was overweight, yet managed to live to a healthy 100, try to find a picture of his boat and inquire about the neighbourhood in which he lived. How much did he earn? Even if your uncle lived in a socialized and developed state such as Canada, and was fairly well off to begin with, his level of health and his risk of mortality, were both affected by each additional dollar. The more money he made, the healthier he became. This held true, even after he achieved the level of income at which he could purchase ten times the required daily dose of vitamins, and have a personal masseuse. According to research, the reason for Uncle's wellbeing was the way his socio-economic status compared to that of others.

It is a well-known fact that socio-economic status plays a role in health and longevity but it is usually attributed to differences in quality of life and access to health care. If these were the only reasons, the rule of diminishing returns would prevail and would assure that no big improvements occur past a certain level of wealth. In fact, gross national product per capita is an important determinant of mortality in developing, but not developed, nations. In addition, countries with a more egalitarian distribution of income have a significant tendency towards lower mortality. What does not fit into this model, is the relationship between longevity and personal wealth. Studies show a linear increase at all income ranges. As a matter of fact, life expectancy in the fanciest neighbourhood in a developed country is probably higher than it is in the second fanciest neighbourhood in the same country. This improvement in health and longevity beyond the elimination of any physical deprivation has been attributed to the psychosocial effect of 'relative wealth'. The way our status in society compares to the status of others, even where only a subtle difference exists, has a profound impact on our level of stress, self-esteem, and social relations, all of which may be extremely important determinants of our health and longevity.

Public health researchers usually control their studies for sex, age, and social class, knowing that these factors impact on health and longevity. Unfortunately, not many studies have looked at the reasons for these effects. The difference between male and female average life spans seems to be biologically programmed (see "Geriatric Superstar Chicks and why they live longer"; G&A; October 2000) but it varies between different societies and over time. This suggests some degree of social shaping by the allocation of roles, risks, prestige and material resources to men and women. Similarly, a relationship between age and health is often due to biological aging, but it may also be due to the social role allocated to people of different age-sets in a particular society. For example, retirement is often followed by depression. Could delaying retirement age and changing our view of elderly's role in society from passive to active, delay aging and the onset of diseases? Could the recent, sudden onset of a high mortality rate in Russia be due to the change in economics that led to massive lay offs of 40 and 50 year olds from the workplace; employees who have virtually no hope of finding another job? Or, could this increase in mortality be a consequence of perestroika and glasnost, which brought Russians a realization of the stark contrast between their economic condition and that of people living in the West?

Perhaps the most important question to ask is at what stage in life these psychological determinants of good health and longevity make the biggest difference? Will a person who has always ranked low on the income scale be better off than a person who lost his or her rank later in life? Alternatively, is it crucial to be born in a good neighbourhood and be driven to school in a fancy car, or can these things be acquired later in life and still have a strong impact on longevity? Certainly, every day is important, and the famous saying "better later than never" definitely applies, but some studies suggest that long shadows are thrown forward from specific socio-economic circumstances. For example, a study that examined the contemporary differences in death rates among three adjacent towns in Lancashire--Nelson, Colne, and Burnley&emdash;traced them to the differences in the socio-economic circumstances of these towns in 1911. On the other hand, interviewed centenarians often describe their life as having been stressful and full of crises, particularly during the first several decades. Also, a study of elderly people with the highest sense of wellbeing, described in the national bestselling book "Pathfinders" by Gail Sheehy, found that passing through a series of life crises, and downfalls in self-esteem, is an essential component of achieving a strong sense of wellbeing later in life.

We are just starting to understand how, and when, our socio-economic status, and its associated sense of wellbeing, affect our longevity. In most part, longevity is still a matter of chance. As the rapidly aging population attracts more attention to this area, future discoveries should bring us a recipe for extending our lives to 120 and beyond.

References

1. MacIntyre S. Journal of Public Health Medicine. 1994;16:53-9.
2. Wilkinson RG. BMJ. 1992;304:165-8.

Nobel Prize in Medicine goes to Investigators of ‘Slow Synaptic Transmission’

Three researchers, Arvid Carlsson, Paul Greengard and Eric Kandel, have been awarded the Nobel Prize in medicine for determining the mechanisms that underlie communication between brain cells. Carlsson's research revealed that dopamine is a key messenger in the brain, a discovery that led to the development of L-dopa, and shed light on the mechanism of action of antipsychotics. Greengard showed how brain cells react to the arrival of dopamine and Kandel demonstrated that changes at nerve synapses are crucial to forming memories. Collectively, these discoveries have enormous implications for the treatment of Parkinson's disease, Alzheimer's disease and schizophrenia.

Breakthrough in Cellular Level Functional Imaging--Broad Implications for Medical and Aging Research

Anna Liachenko, BSc, MSc
Managing Editor,
Geriatrics & Aging

In a stunning presentation at the National Academy of Engineering meeting, Thomas J. Meade of the California Institute of Technology presented frog embryos unfolding from egg to tadpole stages. The images provided an unprecedented degree of cellular resolution, allowing one to see a cell reacting to alterations in a single gene. The technique perfected by Meade and his colleagues represents a major advance in functional nuclear magnetic resonance (NMR) technology.

Positron Emission Tomography (PET) and functional magnetic resonance imaging (fMRI) are both known to reveal sites in the living brain or other tissues that are active when a person is engaged in performing a particular task. These techniques have provided an extraordinary amount of biological information and are among the most important advances in medical science.

The Meade technique uses a novel contrast agent that identifies specific cells when their genes are turned on. NMR relies on the detection of vibrations in hydrogen atoms of water that are induced by a magnetic field. Contrast agents, such as gadolinium, are often added to enhance hydrogen's signal emission. This technique provides a powerful means to image the topography of soft tissue, but cannot provide a deeper level of resolution.

Meade has discovered an elegant and economical solution to one of the most significant problems in biological science: how to provide functional images of cellular level activity. He solved this problem by constructing a 'molecular basket' for each gadolinium ion. The basket consists of claw-like molecules called chelators. He then created a lid for the basket made out of galactopyranose. The 'closed basket' was injected into both cells of a two-cell frog embryo. One of the two cells was also injected with the gene for galactopyranose-digesting enzyme. Upon synthesis of the galactopyranose-digesting enzyme, the galactopyranose 'lid' was digested, exposing gadolinium to water, resulting in a bright signal. The principle of this technique can potentially be used for detecting any enzyme. Thus, one can create a general method for tracking the changes in any cell, or cellular pathway. Even more exciting is research aimed at finding a way of attaching a drug to the 'basket' and activating it with a particular enzyme within a cell. The potential for this new delivery system is enormous.

Advances in aging research will require understanding the activities and interactions of hundreds of genes. The ability to resolve functional NMR images down to the cellular level will have enormous implications for this research.

Endocrinology of Aging

JE Morley, L van den Berg, editors
Humana Press, Totowa NJ 2000
ISBN 0-89603-756-8.

Reviewed by: Barry Goldlist, MD, FRCPC, FACP

This textbook is an American multi-authored text. As is usual in such books, there is some qualitative variability from chapter to chapter. Unlike some American texts, it does feature some contributors who do not work in the USA. In fact, two Canadian geriatricians wrote the chapter on Diabetes in the Elderly, Graydon Menelly from the University of British Columbia and Daniel Tessier from the University of Sherbrooke.

The introduction, on the Biological Theories of Aging, is very cursory, but does provide a reasonable overview for the neophyte. There are relatively few references from 1995 on for this chapter, but it is probably adequate for this type of text. The chapter on age-related decline, entitled "Tithonusism" after the character in Greek mythology, is well written and provocative, although I doubt whether the term "Tithonusism" will ever catch on. It is just too difficult to pronounce!

Of all the chapters, the one by John Morley on "Testosterone" is by far the best. There are three reasons for this: First, Morley offers a wonderful historical perspective on research in the field. Secondly, the evidence on the role of testosterone in aging is very clearly presented, and any management suggestions are clearly evidence based. Finally, the writing style is wonderfully accessible. I felt as though I was having a conversation with an expert, not reading an academic text. Most of the chapters do not measure up to this one, but there are still some excellent sections. The chapter on diabetes is very thorough and academic, and the management options are clearly spelled out. Some chapters seem a bit out of place, e.g., gynecomastia, and others simply describe a disease common in the elderly such as Paget's Disease of Bone. I suspect that this chapter would be no different if it appeared in a standard textbook on endocrinology.

On the whole, I feel this is a useful text. Its most likely audience would be specialists in geriatrics and endocrinologists with a particular interest in aging. It would also be a worthwhile text for institutional libraries to obtain.

First Robust Demonstration of Extended Life Span Reported

Researchers at the Buck Institute for Age Research in California have, for the first time, demonstrated that the life span of an organism can be extended by the use of synthetic drugs. The authors tested the theory that reactive oxygen species are responsible for the damage that is caused to tissues from aging. They augmented the natural antioxidant systems of a nematode worm, Caenorhabditis elegans, using a small synthetic dismutase/catalase mimetic. The enzymes, superoxide dismutase and catalase, are involved in the removal of toxic reactive oxygen species. Worms that had been treated with the drugs had their life span increased by a mean of 44%, and treatment of worms aging prematurely resulted in the normalization of their lifespan. These results support the belief that oxidative stress is a major determinant of life span, something that has been previously demonstrated in studies on fruit flies (see interview with Dr. John Phillips in the June 2000 issue of Geriatrics & Aging). More importantly, these studies show that the aging process can be counteracted through pharmaceutical intervention.

It is hoped that these drugs could be used to stave off diseases that are associated with old age, such as Alzheimer disease and Parkinson's. The researchers are continuing their studies on the anti-aging therapy in mice, and preliminary results appear to show that the drugs are extending the mouse life span. Next year the scientists hope to test the drugs in clinical trials of elderly patients who have suffered a stroke.

Source

1. Melov S, Ravenscroft J, Malik S, Gill MS et al. Extension of Life-Span with Superoxide Dismutase Mimetics. Science 2000, 289(5484):1567-1569.

Geriatric Superstar Chicks and Why they Live Longer

It is August 14th and I am looking at this morning's headline in the Globe and Mail--"Invisible scientist, geriatric astronauts in dead heat." One can only pity future historians assigned to deciphering the hieroglyphics of our era! The headline refers, of course, to the big blockbuster hit of the summer, Space Cowboys. This movie is being described in the media as a "Geriatric NASA adventure". Beat that!

Well, two writers in the National Post tried to do just that. Playing on the public's insatiable interest in 'aging' male stars, the two writers, Botsford and Botsford-Fraser, put forward a movie premise that spoofs Space Cowboys. Their movie concept is titled, "Geriatric Superstar Chick Flick". Here is the concept: "four gorgeous, superstar, action hero, geriatric babe nuclear-sub experts reunite for a spectacular-underwater adventure." Although the premise might not appear sellable from the standpoint of a 'big' Hollywood producer, it is in step with the reality that a growing part of the population consists of "geriatric babes".

Not only are there more "geriatric babes" in society, but they are living longer and highlighting the difference in life span between men and women. Today, women in both developed and developing nations live approximately 7-10 years longer than men. This is not a statistical anomaly or a product of inequities in health care. On the contrary, men enjoy many physical and cultural advantages; for instance, men are typically stronger, faster and less overweight than women. They are generally wealthier, and have, historically, had better access to employment, education and health care. Studies show that men receive medical care more promptly for potentially lethal conditions. Also, until recently, many drugs have been approved on the basis of trials conducted predominantly on men. Should not all of these factors have given men a decided longevity advantage? Since the answer is no, what puts women so far ahead of the game? Although, we are only beginning to unravel the mysteries of aging, some research is beginning to emerge which sheds light on the gender discrepancy in life span.

Consider the following: The records of women outliving men date back to the earliest reliable church records or to the1500s.1 Back then, women lived an average of 36.6 years compared to 33.7 years for men. The female life span has increased by 77% since 1900, while the life span of men increased by only 66% during the same time period. Today, two-thirds of all people over the age of 65 are women. Among centenarians, 85% are women. Moreover, female centenarians as a group live several years longer than male centenarians.7

A phenomenon so universal should have it origins in evolution and genetics. Thomas Perls and Ruth Fretts of Harvard's Medical School, whose research focuses on this gender gap discrepancy, attribute the difference to the fact that "female longevity is more essential, from a Darwinian perspective, than the prolonged survival of males." Females are instrumental to the nurturing of offspring; consequently, this assures the passing of female genes to the next generation. By contrast, the critical factors for passing on male genes to the next generation is the practical necessity of safeguarding both the availability of males to females and the longevity of mothers, not the longevity of the males themselves.

If, indeed, female longevity is vital to the survival of the species, one should find multiple behavioral and physiological mechanisms that would reinforce this survival advantage. And indeed, recent research has revealed a number of interesting facts.

First, and perhaps most obvious, are the sex hormones. Testosterone has been found to be 'toxic' to the organism. Not only does testosterone promote aggressive and risky behaviour, potentially causing accidents and deaths, but it also increases levels of low-density lipoprotein, raising the male's chances of getting myocardial infarction and stroke. On the other hand, estrogen appears to be rather beneficial to the body. It lowers levels of low-density lipoprotein and raises levels of high-density lipoprotein by regulating the activity of liver enzymes involved in cholesterol metabolism. Estrogen also possesses antioxidant properties, thereby preventing DNA damage and cancer. Though this is still a subject of debate, studies indicate that estrogen administration after menopause lowers the risk of death from myocardial infarction and stroke and, importantly, the risk of dying in general.2,3 The trends connecting estrogen replacement therapy and longevity are, obviously, relatively recent and need to be confirmed in the future. What is clear is that one may want to think twice about taking testosterone for a boost later in life.

Another factor now thought to contribute to female longevity is menstruation. The regular bleeding, so often blamed for low blood and iron levels in pre-menopausal women, may actually contribute to longevity.4,5,6 Bleeding lowers the number of iron ions, essential to the formation of oxygen radicals, which, in turn, have been implicated in aging and cancer. Instead of being a defect, women's predisposition to light anemia may, in fact, be a mechanism for slowing down aging. Interestingly, a study performed at the University of Minnesota found that males who give frequent blood donations have a reduced oxidation of low-density cholesterol.

The 'last but not the least' explanation for the prolonged longevity of females may lie in the X-chromosome, which has been found to possess a gene crucial for DNA repair. Even though females undergo X-chromosome inactivation during adulthood and have only one active copy, similar to males, the inactivated X-chromosome seems to become more and more active with age. This 'shadow' activation can compensate in some fashion for the potential damage to the primary active X-chromosome in women. Men obviously do not have this advantage.

It would seem that there is a host of genes regulating senescence that could be targeted in an investigation of the genetic determinant of life span. Genes encoding sex hormones and genes controlling metabolism are good candidates. These genes are tuned to environmental and physiological cues that trigger repressor and effector mechanisms of senescence. Cues, such as reproduction and timing of reproduction, are the critical factors in the genetic nexus that controls these mechanisms. Since reproduction requires an enormous increase in resources, the body is intricately programmed to suppress reproduction until the time when sufficient resources are available. Delayed reproduction seems to repress senescence. Caloric restriction, with its demonstrated effect of slowing down aging, may in fact, be tied into this underlying mechanism, i.e., the body gets enough resources to maintain essential body systems but not enough to reproduce. In fact, starvation has been shown to suppress ovulation. This, of course, would indicate that women planning to conceive should not exercise caloric restriction. It would be interesting to find out whether this mechanism works in reverse: if one staves off having children, will certain life-extending mechanism be activated to ensure a sufficient time frame for rearing offspring later in life. Studies have shown that women centenarians are more likely to have given birth in their forties than women who died in their seventies. However, it is just a correlation and no causality has been established. With the introduction of the oral contraceptive, we have witnessed a startling increase in the age at which some women are having children. It remains to be seen what consequences this will have on the life span of the current generation or the next one.

In conclusion, it appears that while men are more 'fit to fight' in the short term, women are much more suited for longevity. However, living longer is not tantamount to being healthier. Statistically, women suffer from many more chronic conditions, such as osteoporosis. As well, men that pass over the so-called 'hump' (60-80 years) are in much better health than women of the same age. New scientific discoveries may find the means to confer the advantages of one sex on the other. In the meantime, you can look forward to next summer's blockbuster--it will have to be a "Geriatric Superstar Chick Flick".

E-mail your thoughts on this editorial and your casting line-up for the "Geriatric Chick Flick" to geriatrics@ribosome.com.

Suggested Reading

1. Perls TT, Fretts RC. Why women live longer than men. Scientific American; June 1999.
2. Liachenko A. HRT controversy unresolved until 2005. G&A; Jan/Feb 1999.
3. Liachenko A. Pharmacological prevention of fractures. G&A; Nov/Dec 1998.
4. Knekt P, Reunanen A, Takkunen H, Aromaa A, Heliövaara M, Hakulinen T. Body iron stores and risk of cancer. Int J Cancer 1994, 56(:3):379-82
5. Gutteridge JM, Halliwell B. Free radicals and antioxidants in the year 2000. A historical look to the future. Ann N Y Acad Sci 2000, 899: 136-47
6. Venarucci D, Venarucci V, Vallese A, Battilà L, Casado A, De la Torre R, Lopez Fernandez ME. Free radicals: important cause of pathologies refer to ageing. Panminerva Med 1999, 41(4): 335-9
7. Statistics Canada http://www.statcan.ca/ Daily/English/990513/s990513c.htm.

The Cell’s Computer--Molecular Structure of the Ribosome is Solved

In another major scientific milestone, researchers at Yale University under the guidance of Dr. Thomas A. Steitz, have resolved the three-dimensional crystal structure of the large ribosomal subunit, one of the cell's most sophisticated organelles, to 2.4 Å.

The ribosome is one of the most crucial components of the cell. The large ribosomal subunit catalyzes peptide bond formation and binds initiation, termination and elongation factors. The bacterium that was used in these studies is Haloarcula marismortui, which is found in the Dead Sea in Israel. The detailed picture of the ribosome includes 2833 of the subunit's 3045 nucleotides and 27 of its 31 proteins and shows the positions of approximately 100,000 atoms. In a related study, researchers have found that the structure of the ribosome consists mostly of RNA rather than proteins. This means that the ribosome is actually a ribozyme, and that proteins are made in the ribosome, by a large complex of proteins and RNA, in reactions that are catalyzed by ribosomal RNA (rRNA). This fact is of enormous significance in that it confirms theories about the significance of RNA in giving birth to DNA, and consequently, the protein-based world.

The nano-molecular structure of the ribosome has long fascinated scientists. With the emphasis in biology shifting dramatically towards understanding biological systems as information processing systems, the ribosome has received renewed attention. The ribosome, in fact, bears an uncanny resemblance to the basic model of computation that underlies all modern computers, known as the Turing model.

A Longer Lifespan and the Human Race

Did you notice the picture of the magnificent redwood trees on this page? One coastal redwood, General Sherman, is over three thousand years old. Remarkably the history of this tree has spanned most of recorded human history. One hundred and twenty human generations have come and gone during the life of this 'wonder' of longevity. We have all reflected, I think, at some time or another on the life span of other species. Sadly, we know that our beloved pooch will not live beyond twenty years and that cats, even with nine lives, will not make it past their 30th birthday. However, species like marine bivalves can live up to 220 years. The great ocean tortoises, seemingly as vigorous at 150 years of age as tortoises that are one hundred years younger, bring new meaning to the expression "one hundred years young".

Longevity has always fascinated mankind. We hear distant and remote echoes of this fascination through the earliest known Hebrew and Greek texts. These texts are replete with stories and tales of long-surviving individuals. For centuries, even well recognized authorities believed these claims of longevity. In the 1800s, however, the French naturalist Georges Buffon "recognize(d) that humans, regardless of their race or social station, rarely lived beyond a hundred years." Later, the British demographer, William Thomas, in his classic 1873 study, expanded upon Buffon's insight by "proving" through a comprehensive examination of insurance company records that "Buffon's upper limit of one hundred years was substantially correct."

What determines that boundary, the upper limit of human life span? William R. Clark, Author of the book A Means to an End; The Biological Basis of Aging and Death, states that consistency of life span across generations and species "can be taken as a priori evidence that [it] is at least in part a genetically determined trait." A gene for longevity has yet to be found. However, it is interesting that, despite numerous studies, very few attributes have been shown to correlate with life span. Metabolic rate is one; slowing metabolism via caloric restriction doubles the life span in some species (see "Eat Less and Drink from the Fountain of Youth", Geriatrics & Aging, June 2000). Gender is another; on average, women live seven years longer than men. This difference in life span between the two genders is a well-known fact, which is often attributed to the higher mortality of males in childhood and middle age. What is not so well known is that female centenarians live consistently longer than male centenarians. The evidence seems to support a genetic factor as a preponderant contributor to longevity. Another important observation, and this may be the very reason why some species are programmed to live longer than others, is that life span directly correlates with the time needed for reproduction and the rearing of offspring.

If life span is under strict genetic control, current research suggests that it may be possible to manipulate the genes governing aging. This area of research is advancing rapidly and the amount of information on age-related gene expression is increasing exponentially (see "Dance of A few Genes", Geriatrics & Aging, June 2000). Tomas Prolla, in an interview published in our June issue, opined that his experiments on skeletal muscle have yielded more information on "aging gene expression than all other previous experiments combined". It is already clear that in the next five years we will learn more about both tissue-specific and systemic aging than has been learned in the last two thousand years of thinking, brooding and inquiring into the mysteries of this process.

If the life span could indeed be increased--and this may not be a utopian dream if the current research actually bears fruit--the implications for our society would be epochal.

Clearly the vast store of human experience and knowledge, which is lost because of early death, could be directed at refashioning the world. The additional years of productive and healthy life would unleash untold and unparalleled amounts of creativity and human potential. On the other hand, this would create an array of challenges to overcome--from the re-organization of our society to accommodate the changing demographics, to the restructuring of some of our basic institutions in order to accommodate different societal priorities and goals.

The social, medical, economic and ethical implications of a lengthier human life span are so complex and daunting that the subject has been shunned as a topic of serious discussion. Developments that are underway in research laboratories around the world make the subject and the topic, however, a matter of special urgency and significance. We intend to make Geriatrics & Aging a forum for discussions on this topic. In 2001, we plan to convene a round-table discussion on aging, with leading authorities in the field, in order to examine in-depth what these implications might be. We invite our readers to participate in this discussion by e-mail and we are also exploring the idea of broadcasting this session over the Internet.

I would appreciate your thoughts and feedback on this subject and your interest in the roundtable discussion. Please e-mail any suggestions or comments to geriatrics@ribosome.com.

Send Us Your Case Study

Do you have a favourite case study that you would like to send us? Do you have a patient with a problem that you are having difficulty treating or diagnosing? As a new feature in Geriatrics & Aging we would like to include case studies from you, our readers, so that you have an opportunity to share some of your more interesting cases or to enable you to obtain opinions from your colleagues. Please forward your case studies to our editorial staff at geriatrics@ribosome.com.