Thursday, June 30, 2011

Climate Change Mirrors an Earlier Era in Planetary History

Doctor Lee R. Kump, a professor of geosciences at Pennsylvania State University, has illustrated some disturbing parallels between the changes in global climate of today with a well-studied era in the planet's past.  At that time, about fifty-six million years ago, temperatures worldwide rose some five degrees Celsius in the course of a few thousand years.  This period is referred to as the Paleocene-Eocene Thermal Maximum (PETM).  At that time in the planet's history the huge land mass known as Pangaea was in the final phase of breaking up into the current day continents.  This process led to the formation of the north-eastern Atlantic Ocean.  As a result, enormous volumes of molten rock were released producing intense heat.  Carbon-enriched sediments that were close to the surface were subsequently burned releasing greenhouse gases into the atmosphere, especially carbon dioxide and methane.   In addition, it is postulated that the concomitant warming of the ocean seabed led to the release of vast quantities of frozen methane.
The cumulative effects of these changes were the following:
  •          Marked increase in global temperatures (as noted above)
  •          Climate zones shifted towards the poles both on land and in the ocean propelling the migration of living things to accommodate this change
  •          Within the ocean depths, acidity increased and the supply of oxygen diminished killing of many organisms there.
These changes are striking similar to what is being reported currently.  In regard to the status of the oceans, an international workshop, sponsored by the International Programme on the State of the Ocean (IPSO), has recently met in Oxford, UK.  Their goal was to study the impact of human-made stressors including warming, acidification and overfishing on the overall health of the ocean.  The conclusions this international group of experts reached are quite alarming.  In essence, they have concluded that the stresses imposed on the world's oceans as a direct result of human activity may lead to "globally significant marine extinction."

In addition, Doctor Kump has determined from his studies that, in fact, "global temperature today is rising much more quickly than it did during PETM."  If the current rate of increase in atmospheric greenhouse gases continues unabated, it is estimated that global temperature will increase by eight degrees Celsius by the year 2400.  This kind of increase would profoundly and dramatically change the nature of life on the planet and drastically impact the possibility of continued human survival.  This kind of change can only be averted by a global commitment to dramatic changes in human behavior and expectations.  It should also be noted that it took some 200,000 years for the planet to cool down during PETM.  

Friday, June 17, 2011

Antibiotic Resistance – A Cause for Global Concern

Penicillin was discovered and developed as the first widely-used anti-microbial (antibiotic) agent in 1928.   Ever since that time, bacteria have developed resistance to a wide range of antibiotics as they have been introduced.  This capability can be explained based on two important properties of bacteria.  These organisms divide approximately every twenty minutes; therefore, through the course of a single twenty-four hour day, seventy-two generations have been produced.  If bacteria are in an environment permeated with antibiotic some of the progeny may develop a resistance due to a spontaneous mutation in their genetic material (DNA).  If this should happen, all the susceptible bacteria will die off leaving behind those that are resistant.  This process can be regarded as natural selection.  Since resistance is conferred by a change in the genetic makeup of the organism, resistance can then be passed on to all the progeny.  There has always been a potential public health risk in regard to this ability of microorganisms to become resistant to these agents.


Bacteria are classified into two distinct groups – gram-negative and gram-positive.  This classification was created based on their ability or inability to take up a particular stain.  A well known example of gram-positive bacteria that is disease producing (pathogenic) is Staphylococcus aureus that is of a particular concern in a hospital setting.  An antibiotic that has been traditionally used to combat this kind of infection is methicillin.  As a result of its universal application, a highly resistance form of this bacteria referred to as methicillin resistant Staphylococcus aureus (MRSA) has arisen.  This has created a serious public health dilemma.


From a public health perspective, a far more problematic issue is antibiotic resistance among gram-negative bacteria.  These bacteria possess a double cell wall that makes them more challenging to eliminate.  An example of a pernicious variety of this kind of bacteria is Klebsiella pneumoniae; this strain is particularly prevalent in hospitalized patients and is a major cause of pneumonia and bloodstream infections (sepsis).  The antibiotics that have been found to be effective against gram-negative bacteria are referred to as the carbapenems.  As one would suspect, Klebsiella has now been shown to possess resistant to the action of carbapenems.


Doctor Timothy Walsh and his colleagues from the Cardiff University, United Kingdom have examined the nature of this resistance and have found that the resistant strain produces an enzyme (NDM-1) that effectively inactivates carbapenems.  This is particularly disturbing since gram negative bacteria, Klebsiella as an example, also possess the capacity to transfer antibiotic resistance to other kinds of bacteria including the ubiquitous Escherichia coli that normally inhabits the large intestines of most mammals.


Given the seriousness of this issue, it is considerably disturbing that there are no new kinds of antibiotics against gram-negative bacteria currently being developed.  This reality holds an ominous prospect for the future in regards to global public health.  

Tuesday, June 7, 2011

Rheumatoid Arthritis – A Possible New Therapy

Rheumatoid arthritis (RA) is a chronic and debilitating illness.  It can strike at any age and seems to be more prevalent in women than men.  Although the specific etiology (cause) of RA is unknown it is categorized as an auto-immune disease – the body's immune system seems to mistakenly recognize normal tissue as foreign and attack it.  Other examples of autoimmune diseases are multiple sclerosis (MS) and Systemic lupus erythematosus (lupus).

The target for the autoimmune reaction in RA is primarily the joints on both sides of the body -wrists, fingers, knees, feet, etc.  The extent of the resulting disability can vary widely depending on other factors related to health.

In order to effectively treat RA, the underlying mechanism that leads to the disease needs to be better understood.  Recent evidence has implicated the so-called tumor necrosis factor α (TNFα) as a major component in the development of this illness.  TNFα is found on the cell surface of immune cells.  TNFα is a member of a group of substances referred to as cytokines.  Cytokines are small protein molecules that are secreted by both the nervous and immune systems.   They have been found to play critical roles in the modulation of the immune system.


Dr. Hao Wu and his colleagues from the Department of Biochemistry at the Weill Cornell Medical College in New York City have shown the disease-producing role of this substance using mouse models of inflammatory arthritis.  Furthermore, this investigative group has demonstrated that Progranulin (PGRN) slows the progression of arthritis in the mouse.  Progranulin is a naturally occurring growth factor for human fibroblasts – cells responsible for the production of collagen, an integral component of the body's connective tissue.  Progranulin seems to exert this inhibitory effect by binding to the receptor that normally binds TNFα, thereby inhibiting its role in the autoimmune process that results in RA.


These findings shed significant light on the immune process.  These data may ultimately contribute towards the treatment of this intractable disease.