HICN608 Medical News Part 3/4 
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 HICN608 Medical News Part 3/4

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3. Shah BV. Software for Survey Data Analysis (SUDAAN) version 5.30 Software
documentation. Research Triangle Park, North Carolina: Research Triangle
Institute, 1989.

4. National Institute on Drug Abuse. National Household Survey on Drug Abuse:
main findings, 1988. Rockville, Maryland: US Department of Health and Human
Services, Public Health Service, {*filter*}, Drug Abuse, and Mental Health
Administration, 1990; DHHS publication no. (ADM)90-1682.

5. National Institute on Drug Abuse. National Household Survey on Drug Abuse:
main findings, 1990. Rockville, Maryland: US Department of Health and Human
Services, Public Health Service, {*filter*}, Drug Abuse, and Mental Health
Administration, 1991; DHHS publication no. (ADM)91-1788.

6. National Institute on Drug Abuse. National Household Survey on Drug Abuse:
population estimates, 1991. Rockville, Maryland: US Department of Health and
Human Services, Public Health Service, {*filter*}, Drug Abuse, and Mental Health
Administration, 1992; DHHS publication no. (ADM)92-1887.

7. Hugick L, Leonard J. Despite increasing hostility, one in four Americans
still smokes. The Gallup Poll Monthly (December) 1991;315:2-10.

8. Maxwell JC Jr. The Maxwell consumer report: third quarter 1992 sales
estimates for the cigarette industry. Richmond, {*filter*}ia: Butcher and Singer,
October 30, 1992; publication no. WFBS-6824.

9. US Federal Trade Commission. Federal Trade Commission report to Congress
for 1990: pursuant to the Federal Cigarette Labeling and Advertising Act.
Washington, DC: US Federal Trade Commission, 1992.

10. Public Health Service. Healthy people 2000: national health promotion and
disease prevention objectives -- full report, with commentary. Washington, DC:
US Department of Health and Human Services, Public Health Service, 1991; DHHS
publication no. (PHS)91-50212.

* Poverty statistics are based on definitions developed by the Social Security
Administration that include a set of income thresholds that vary by family
size and composition.

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Volume  6, Number  8                                            April  4, 1993

                   Publication of CDC Surveillance Summaries
                   SOURCE: MMWR 42(12)   DATE: Apr 02, 1993

     Since 1983, CDC has published the CDC Surveillance Summaries under
separate cover as part of the MMWR series. Each report published in the CDC
Surveillance Summaries focuses on public health surveillance; surveillance
findings are reported for a broad range of risk factors and health conditions.
     Summaries for each of the reports published in the most recent (December
11, 1992) issue of the CDC Surveillance Summaries (1) are provided below. All
subscribers to MMWR receive the CDC Surveillance Summaries, as well as the
MMWR Recommendations and Reports, as part of their subscriptions.

               TETANUS SURVEILLANCE -- UNITED STATES, 1989-1990

     During the period 1989-1990, 117 cases of tetanus were reported from 34
states, for an average annual incidence of 0.02/100,000 population. Fifty-
eight percent of patients were greater than or equal to 60 years of age, while
seven (6%) were less than 20 years of age, including one case of neonatal
tetanus. Among {*filter*}s, the risk of tetanus in those greater than 80 years of
age was more than 10 times the risk in persons ages 20-29 years. The case-
fatality rate increased with age, from 17% in persons 40-49 years of age to
50% in those greater than or equal to 80 years of age. Only 11% of patients
reported receipt of a primary series of tetanus toxoid before disease onset,
while 31% lacked a history of tetanus vaccination. Tetanus occurred following
an acute injury in 78% of patients. Of patients who sought medical care, only
58% received tetanus toxoid as part of wound prophylaxis. Tetanus remains a
severe disease that primarily affects unvaccinated or inadequately vaccinated
older {*filter*}s. Increased efforts are needed to reduce the burden of tetanus
among the elderly. Health-care providers should take every opportunity to
review the vaccination status of their patients and provide tetanus vaccine
when indicated. Authors: Rebecca Prevots, Ph.D., M.P.H., Roland W. Sutter,
M.D., M.P.H. & T.M., Peter M. Strebel, M.D., M.P.H., Stephen L. Cochi, M.D.,
Stephen Hadler, M.D., Division of Immunization, National Center for Prevention
Services, CDC.


     The licensure of whole-cell pertussis vaccine combined with diphtheria
and tetanus toxoids as DTP in the 1940s -- and its widespread use in infants
and children -- led to a dramatic decline in the incidence of reported
pertussis. In the prevaccine era, the average annual incidence and mortality
for reported pertussis were 150 cases and six deaths per 100,000 population,
respectively. From 1989 through 1991, pertussis cases were reported by state
and local health departments to CDC through two distinct national surveillance

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Volume  6, Number  8                                            April  4, 1993

systems: the National Notifiable Diseases Surveillance System (NNDSS) and the
Supplementary Pertussis Surveillance System (SPSS).
     During the period 1989-1991, 11,446 pertussis cases were reported to the
NNDSS (4157 in 1989; 4570 in 1990; and 2719 in 1991), for an unadjusted annual
incidence of 1.7, 1.8, and 1.1 cases per 100,000 population in 1989, 1990, and
1991, respectively. For the period 1989-1991, case reports were received
through the SPSS on 9480 (83%) of the 11,446 patients reported to the NNDSS.
Age-specific incidence and age-specific hospitalization rates were highest
among children less than 1 year of age and declined with increasing age.
     Long-term trends suggest an underlying upward trend in the reported
incidence of pertussis in the United States since 1976. The peak in reported
pertussis cases in 1990 represents the highest annual incidence of pertussis
since 1970. However, the incidence of pertussis declined 41% from 1990 through
     Whether the long-term upward trend in reported pertussis is a true
increase in incidence is unclear; the observed increase may be a function of
improved surveillance. To better estimate the true incidence of pertussis, the
surveillance system needs to use a sensitive and specific case definition, and
the information collected needs to be as complete and accurate as possible.
Because available diagnostic tests vary in sensitivity and specificity, the
following steps should be taken to improve surveillance for pertussis in the
United States: a) increase physician knowledge of the clinical presentation of
pertussis; b) encourage more widespread use of culture, the current "gold
standard" of pertussis laboratory diagnosis; and c) encourage the use of
uniform clinical case definitions as recommended by the Council of State and
Territorial Epidemiologists and CDC. Authors: Susan F. Davis, M.D., Peter M.
Strebel, M.D., M.P.H., Stephen L. Cochi, M.D., Elizabeth R. Zell, M.Stat.,
Stephen C. Hadler, M.D., Division of Immunization, National Center for
Prevention Services, CDC.


1. CDC. CDC surveillance summaries (December 11). MMWR 1992;41(no. SS-8).

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Volume  6, Number  8                                            April  4, 1993

                        cooking.net">food & Drug Administration News

   P93-9                                       cooking.net">food and Drug Administration
  FOR IMMEDIATE RELEASE                       Monica Revelle - (301) 443-3285
    March 30, 1993                                (Home) -- (410) 290-6575

    The cooking.net">food and Drug Administration today announced approval of a combination
vaccine against four serious illnesses that affect small children.  When
started in infancy, the new combination vaccine will allow immunization
against the diseases using four injections, instead of the eight injections
which are currently needed.  
    The diseases are diphtheria, tetanus, whooping cough (pertussis) and
Haemophilus influenza type b, the leading cause of meningitis.  
    "As secretary of HHS, I call this good news.  If I were an infant about to
get four fewer shots, I'd call it great news," said HHS Secretary Donna E.  
    The new vaccine is composed of diphtheria and tetanus toxoids and
pertussis vaccine adsorbed (DTP), and Haemophilus b conjugate vaccine.  A
series of four injections of the combination vaccine has been found to be as
effective as the eight injections of the DTP and Haemophilus b conjugate
vaccines that have been used to provide protection against the same diseases
for almost a decade.  
    "Any new product that reduces the need for medical procedures without a
loss of effectiveness is a step in the right direction," said FDA Commissioner
David A. Kessler, M.D. "We're satisfied that the combination vaccine is safe
and gives children the protection they need."
     The new vaccine is recommended for use in children at 2, 4, 6 and 15
months of age.  The clinical trials included 6,793 children who were immunized
with the combination product and 4,232 children who were immunized separately
but simultaneously with the two older vaccines.  
    The results showed no significant difference in antibody response between
the two groups. The vaccines were comparable in the frequency and types of
adverse reactions reported, the most common of which were fever, redness and
inflammation at the injection site, and irritability.  
    The combination vaccine is manufactured by Lederle Laboratories and Praxis
Biologics, Inc., subsidiaries of American Cyanamid Co. in New York, N.Y.  The
product will be marketed under the name Tetramune.  
    Most children have their required vaccines by the time they enter school.  
But since many infectious diseases are particularly dangerous in very small
children, public health officials have sought to get children immunized before
age 2.  
    To be appropriately immunized by the age of 2 years, a child often will be
given three of the following four shots -- DTP, Haemophilus influenza type b,

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Volume  6, Number  8                                            April  4, 1993

hepatitis B and measles-mumps-rubella vaccine -- at the same time, at sessions
at two months, four months, six months and 15 months. (Polio vaccine is given
orally at three of these times as well.) Combining Haemophilus influenza type
b in a single vaccine with DTP could reduce the shots to as few as two at each
session -- and also reduce the total number of injections needed during this

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Volume  6, Number  8                                            April  4, 1993

   P93-8                                       cooking.net">food and Drug Administration
   FOR IMMEDIATE RELEASE                       Sharon Snider--(301) 443-3285
     March 2, 1993                               (Home) -- (301) 622-0977

    The cooking.net">food and Drug Administration today announced that it has cleared for    
marketing the first cholesterol test available for home use by consumers        
without a prescription.  
    Previously, cholesterol tests, which are used to help determine the risk    
of heart disease, were available only for use by medical professionals.  
    The test--the Accumeter Cholesterol Self-Test, made by Chem Trak Inc. of    
Sunnyvale, Calif.--comes in a kit and allows the user to find the level of      
cholesterol in the {*filter*} in about 15 minutes.  
    "This test can help give consumers greater opportunity to monitor their    
health and take steps to prevent disease," said Health and Human Services      
Secretary Donna E. Shalala.  "Making it more convenient to check on            
cholesterol can help ensure that people are aware of the level so they can see  
a doctor before serious problems develop."
    High cholesterol is only one factor that leads to heart disease.  Others    
include high {*filter*} pressure, smoking, obesity and family history of heart      
disease before age 55.  An estimated 17.6 million Americans have heart          
disease, which claims some 734,000 lives in the United States annually.  
    The agency's decision to allow the test to be sold over-the-counter is      
based on results of a multi-center clinical trial involving nearly 500          
{*filter*}s.  The firm's study showed the test to be as accurate as cholesterol
tests used by doctors and medical laboratories.  
    "Accuracy is crucial," said David A. Kessler, M.D., Commissioner of cooking.net">food    
and {*filter*}.  "It is also important, as the study showed, that participants were  
able to read and understand the instructions and perform the test without      
assistance," he noted.  
    To perform the test, the user {*filter*}s his finger, squeezes {*filter*} into a      
cassette that contains a test strip and then waits 10 to 15 minutes for        
results.  The strip changes color as the cholesterol rises on it.  When the    
time is up, the user compares the height of color shown on the cassette with    
an accompanying conversion chart to get the cholesterol reading.  
    The test measures total cholesterol.  It does not measure individual        
components, such as LDL or HDL cholesterol.  A reading of less than 200 is      
desirable; 200 to 239 is borderline high; and 240 or above is high, meaning    
the user may be at a greater risk for heart diesase.  People whose cholesterol  
is borderline or high should see a doctor.  
    The National Institutes of Health's National Cholesterol Education Program  
recommends that people with a reading in the desirable range have their        
cholesterol checked once every five years, and that those whose cholesterol is  
borderline or high follow the recommendation of their doctor for frequency of  
    The home test should not be used by hemophiliacs or by people who take      

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Volume  6, Number  8                                            April  4, 1993

medicine to thin {*filter*} because of the possibility of excessive bleeding from    
the finger {*filter*}.  Those individuals should have their cholesterol checked by  
their doctors.  
    The package labeling for the test includes detailed instructions for        
proper use and a discussion of the test's limits.  It also includes            
information on cholesterol, heart disease, diet and exercise and lists a        
toll-free number consumers can call for additional information.  The number is  
    Other home tests approved by FDA include tests for ovulation, pregnancy,    
{*filter*} glucose, hidden fecal {*filter*}, {*filter*} pressure and urinary tract
    FDA and NIH are among the eight Public Health Service agencies within the  
Department of Health and Human Services.

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Volume  6, Number  8                                            April  4, 1993

             IV Drug Cladribine for Treatment Hairy Cell Leukemia
 P93-7                                           cooking.net">food and Drug Administration
  FOR IMMEDIATE RELEASE                           Susan Cruzan--301-443-3285
    March 2, 1993                                   (Home) -- 301-926-7081

   The cooking.net">food and Drug Administration today announced approval of a              
one-treatment intravenous drug for hairy cell leukemia, a rare, often fatal    
cancer of the {*filter*} and bone marrow.  
   The drug, cladribine, with the trade name of Leustatin, is given to          
patients in one continuous treatment over a seven-day period rather than in    
several separate treatments over a period of months, as required for other      
cancer {*filter*}.  While most cancer {*filter*} act on one specific stage of cell        
activity, cladribine destroys both dividing cells and cells at rest.  
   The U.S. approval is the first in the world.  "The drug provides an
important new option for patients with hairy cell leukemia," said FDA
Commissioner David A. Kessler, M.D.  "The single treatment  required with this
drug represents a significant advance."
   In clinical trials, 89 percent of patients treated once with Leustatin      
experienced either complete or partial remission of their cancer for eight to  
25 months.  Signs of remission include a return to normal {*filter*} and bone        
marrow counts without disease symptoms such as fatigue, anemia and recurrent    
   At present, patient followup is too short to assess the long-term benefits  
of the drug.  For this reason, the company will be following patients who took  
part in the clinical trials and reporting the results to FDA.  
   Because only one treatment is required, patients may not experience some of  
the recurrent side effects frequently associated with multiple treatments,      
such as nausea, vomiting, headaches and rashes.  The most serious side effects  
associated with Leustatin include fever and a low white {*filter*} cell count        
during the first two months after treatment.  
   Hairy cell leukemia is named for the "hairy" appearance of the cancer cells  
under the microscope.  The disease currently affects about 3,000 patients,      
mostly men.  About 600 new cases occur each year.  Due to the low incidence of  
the disease, Leustatin has been designated as an "orphan" product.  This        
designation provides incentives for companies developing products for rare      
diseases -- those affecting fewer than 200,000 people in the United States.  
   The drug was granted a treatment IND in early l992, allowing its expanded    
use prior to approval.  It will be marketed by Ortho Biotech Inc., of Raritan,  
N.J., an affiliate of Johnson and Johnson.  
   FDA is one of the eight Public Health Service agencies within HHS.

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Volume  6, Number  8                                            April  4, 1993


                             Bone, Muscle, Motion
                      Arizona State University "Research"
                                   Fall 1992
                  Copyright 1992, Reproduced with Permission

Walking is a basic human activity that most of us take for granted.  But try
to build a computer model of a stroll across the room, without the benefit of
a versatile controller such as the central nervous system, and the fundamental
becomes complex.  ASU biomedical engineers are answering the challenge.  

SIT DOWN. STAND UP. WALK across the room. Pick up a book. Turn the page. Most
of us have the luxury of taking for granted the ability to perform such simple
everyday movements. But even the simplest movement involves an incredibly
complex series of com-mands and responses between the brain and body.  

Walking across the room requires a million different nerve impulses, balance
techniques, the defiance of gravity, billions of brain responses, activation
of certain muscles, inactivation of others, and many hundreds of other
mechanical processes, all precisely coordinated by the central nervous system
in intervals quicker than a billionth of a second. Yet we do it all day long
without a specific thought.  

Gary Yamaguchi does spend a lot of time thinking about the processes involved.  
He must if he hopes to create a truly effective model of human movement. An
assistant professor of biomedical engineering at Arizona State University,
Yamaguchi and his graduate students are developing complex three-dimensional
computer models that accurately match the intricate interactions occurring
between muscles, tendons, ligaments, and bones during simple movements such as
a stroll across the room.  

In a healthy human, once the decision to move is made in the brain, the normal
cascade of events by which movements are produced "flows" outward from the
nervous system to the muscular and skeletal systems.  

Yamaguchi's area of research is known as "dynamic musculoskeletal modeling."  
By building and studying representative computer models and simulations, he
and other scientists hope to better understand the causal relationship between
applied muscular forces, or joint movements, and the body motions that result.  

"Using an effective computer model as reference, the idea is to analyze the
specific nuances of how the body creates coordinated movement" Yamaguchi

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Volume  6, Number  8                                            April  4, 1993

explains. Supplied with that knowledge, bioengineers, surgeons, and other
physicians can work together to develop more effective procedures and more
efficient devices to assist the disabled.  

In one of many projects currently in progress at his laboratory, Yamaguchi and
graduate students Dan Moran and Jonathan Green are working to develop a
computerized model that will assist surgeons to improve orthopedic surgical
techniques for children with cerebral palsy. Surgery often is necessary to
prevent bone deformities in these children.  

Portions of the brain in a person with cerebral palsy are, in effect, dead.  
As a result, their ability to stop or control motor reflexes is missing.  

"If you or I touch the table, we know that it is not a hot stove. Our reflex
activity is inhibited" Yamaguchi explains. "But if a child with cerebral palsy
hits the table or something moves his joint very quickly, his uninhibited
reflexes cause the muscles to contract uncontrollably."

Cerebral palsy patients are relaxed while asleep. But when awake, some
stimulus constantly triggers their muscles to contract. If unchecked, this
constant pressure of abnormal forces will cause growing bones to deform.  

To prevent deformities, standard surgical procedure is to cut, lengthen, or
relocate tendons, the relatively inelastic strands of connective tissue that
attach muscles to bones. The result is a reduction of force acting on the
bone, which in turn reduces the chance for deformity.  

But splitting or lengthening the tendons also reduces a muscle's effectiveness
in making controlled, coordinated movements. If successful, Yamaguchi's
computer model will be able to predict and depict the resulting walking
patterns in animated form, which surgeons can study before entering the
operating room.  

"Our work is an effort to help the surgeons optimize their procedures,'
Yamaguchi says.  "Right now, surgeons do their work based on experience. They
are very good, but it takes a long time to develop that level of expertise.  
We want to help.  

"By performing the operation on our computer model before surgery, we hope to
tell surgeons the best way to achieve an optimal balance, that is, how best to
operate to prevent deformity and still allow the child useful function of his
arms or legs."

Surgeons also tend to perform these operations in a sequential, conservative
fashion. If the patient needs surgery on the hip, knee, and ankle, for

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Volume  6, Number  8                                            April  4, 1993

example, common practice is to operate on the worst first and then see how the
patient responds. The wait can be months, even years between surgeries.  

"With an effective computer model, the surgeon can plan multiple operations
all at once and still achieve the desired outcome. The model will allow us the
ability to predict out-come without the wait,' Yamaguchi says.  The ASU
biomedical engineer is quick to add that an effective computer model can be
used to gather new information as well as assist with the application of
acquired knowledge.  

Working with physicians at the Harrington Arthritis Research Center in
Phoenix, Yamaguchi and his students use a force platform linked with a
sophisticated video camera system to measure how cerebral palsy patients walk
both before and after surgery.  

They plug the information they gather into the model. In addition to analyzing
the nuances of a prerecorded experiment, the ASU researchers can use the
computer's power to change variables and make predictions.  

"How do we explain all of this data once it's collected? That's my job--the
job for the model,' Yamaguchi says. "Once we can explain it, we can use the
model in both directions. We can take the data and turn it around to make
predictions. This is called forward simulation."

"Physicians want to know if surgery changes the muscle activation patterns in
cerebral palsy patients,' Yamaguchi says. "Surgery changes the mechanics of
their bodies. But do their brains or central nervous systems adapt or not?  

"If you ask most surgeons, they would say that a spastic muscle will always be
spastic. But we don't know how spastic it is. We don't know what the muscle
forces are,' he continues. "We can use our computer model to find answers.  

"Of course, we'll never be sure that the answers we get with a computer are
absolutely correct. But there are no absolutes, only more accurate
predictions. There is no way of checking short of plugging electrodes and
wires and force transducers inside of a person's body to make direct

                             THE CONTROL MECHANISM

Scientists gather new information by using computer models to analyze
interactions between the muscular and skeletal systems. But control resides in
the central nervous system.  A true real world model of human movement must be
extended into what might be called a neuromusculoskeletal model.  

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Volume  6, Number  8                                            April  4, 1993

The level of control--simple or complex--exerted by the human neuromuscular
system to control movement continues to be a matter of conjecture among
scientists. "Walking certainly seems to be a simple task compared to the
difficulty of catching a ball on the run or playing the organ,' Yamaguchi and
colleagues wrote in a paper that presents their ideas on computer model
formulation and control.  

"What is simple to the central nervous system is still quite difficult for us
to understand.  Our hope is that modeling, in addition to experimental
studies, will someday lead us to that understanding,' they wrote. Current
models might provide clues as to how the central nervous system controls
movement. "But the engineering side of me wants to know how to make it happen
in an artificial or paralyzed limb" Yamaguchi adds. "Engineers want to know
how to use it as well as why. Only then can we apply the knowledge to design
devices and improve procedures to assist the disabled."

To date, medical researchers have been unable to find a way past damaged
nerves to restore lost functions even though the brain remains capable of
sending a nerve impulse.  Tiny implantable microchips may be the answer. But
such devices probably are still years or decades away from reliable use.  

To attain effective, coordinated control of an artificial, damaged, or
paralyzed limb, that device or limb needs to communicate with many nerve cells
just as the brain does. But like the brain. it must talk to one nerve cell at
a time, otherwise noise from other cells nearby will drown the message.
Ordinary wires are much too big to do the job.  

Biomedical engineers know that muscles are activated via electrical
stimulation transmitted through the nervous system. They can make muscle
tissue contract using tiny jolts of electricity. But attaining the fine level
of control needed to equate muscle contraction with coordinated movement is
the ultimate challenge.  ASU's James Sweeney is working on that problem. He
and Yamaguchi plan collaborative studies at several levels to improve the
computer model.  

Sweeney, also an ASU assistant professor of biomedical engineering, has
studied functional neuromuscular stimulation (FNS) as a doct{*filter*}student and
research professor at Case Western Reserve University in Cleveland.  

Defined in simple terms, FNS is the application of electrical signals to
muscle tissue to make it contract. For years, most FNS research was targeted
at paralyzed muscle tissue. The line of reasoning was that if the muscles
could be artificially stimulated, perhaps some form of movement could be
restored in para and quadriplegics.  

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"Much of my early research dealt with the problem of helping paralyzed people
to move again,' Yamaguchi says. "We use our computer model to project forward
20 years and ask, 'Can we really do this?' Jim Sweeney is one of the guys who
is really doing the kind of work that will make our dreams a reality"

Sweeney says that current FNS systems designed to assist movement in paralyzed
people require as many as 80 electrodes attached to various muscles. All must
be controlled at the same time. From the engineer's point of view, that is
quite difficult.  

One of the ideas that Sweeney and his colleagues are devising is an electrode
system that is attached deeper into the central nervous system, actually away
from the muscles and closer to where major nerve bundles branch off the spinal
column. These nerve bundles control groups or areas of muscle.  

"Our electrode system would attach along major peripheral nerves that run from
the spinal cord to the muscles" Sweeney explains. "The purpose would be to
control a number of muscles attached to a common peripheral nerve using only
one compact electrode system.  Compared with trying to control 80 or more
electrodes, a smaller number of implants that control multiple muscles would
be much more manageable and probably more reliable."

                            NEUROLOGY'S HOLY GRAIL

In a project funded by the Whitaker Foundation that is electrical in nature
but separate from his FNS research, Sweeney is working on one aspect of what
many consider the "Holy Grail of Neuroscience" the actual healing and
regeneration of damaged nerve tissue within the central nervous system.  

Fairly recent results reported by some scientists indicate that low level
electric fields might actually assist the regeneration process in a damaged
nervous system. Sweeney's work is targeted at helping nerves repair

"Ours is just one of many different approaches, which include tissue
transplants and nerve-grafting procedures,' he says. "Most of the work is
physiological or clinical in nature.  There is not much from the
bioengineering perspective, and very little in terms of simulation or computer

Some experimental results seem to indicate that careful application of very
low intensity electric fields can assist, accelerate, and actually direct the
regrowth of damaged nerve tissue.  Sweeney and doct{*filter*}student Farhad
Musallaie are building a computer model that tests the logic of those
findings. The mathematical model will simulate what happens to nerve cells

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Volume  6, Number  8                                            April  4, 1993

when they are damaged.  

"The next step will be to create an electrical engineering model that
simulates how electric fields actually penetrate and are conducted along
nerves, then combine that with the nerve model to see how the proposed
mechanisms are possible,' Sweeney explains.  

The ASU scientist hopes that the model might provide clues on how to best
apply electric fields in damaged tissue to assist the regeneration process.  

"There also is evidence that electric fields can inhibit as well as assist
regeneration,' he adds. "Our goal is to work out the details. Then we can
determine which electrode systems, current levels, and methods of distribution
work best."

Yamaguchi's musculoskeletal modeling research is supported by the Whitaker
Foundation, the National Institutes of Health, and the National Science
Foundation.  Sweeney's work on functional neuromuscular stimulation has been
funded by the National Institutes of Health.  His work on modeling of nerve
regeneration is supported by the Whitaker Foundation.  For more information on
these or other projects, contact Gary Yamaguchi, Ph.D., or James D. Sweeney,
Ph.D., Department of Biomedical Engineering, College of Engineering and
Applied Sciences, (602) 965-3313.  

HEART MUSCLE is amazing material. In the developing human, heart cells begin
contracting to pump {*filter*} several months before birth. Once started, these
cells never stop until death, working together to make the heart beat an
average of 70 times every minute, 100,000 times a day, 40 million times each
year. Bioengineers who design artifi-cial replacement parts have yet to find
materials that can match this level of natural durability.  

But some scientists are returning to the source--the human body itself--in an
ongo-ing search for materials to repair damaged or diseased heart mus-cle. ASU
biomedical engineers James Sweeney and Eric Guilbeau are among a growing group
of researchers studying the possibility of transplanting skeletal muscle from
other portions of the body and using it to assist damaged hearts with the non-
stop business of pumping {*filter*}.  

"Such muscle transplantation would serve as an alternative to actual heart
trans-plants or to the installation of artificial devices" Sweeney says. The
technical jar-gon for such a procedure is cardiomyoplasty --the grafting of
muscle onto the heart.  

The human body contains lots of skeletal muscle. A surgeon can remove a

Health InfoCom Network News                                            Page 41
Volume  6, Number  8                                            April  4, 1993

portion of muscle from the back or thigh and then graft it onto or into the
heart, that is difficult enough.  But the difficulty only increases from that
point, because skeletal muscle cells are not the same as heart muscle cells.
Skeletal muscle may be extremely strong, but it tires and requires periods of
rest to be effective. Heart muscle cells rest only between beats.  

Still, the fatigue factor is not an insurmountable problem. Scientists now
know that skeletal muscle can be controlled and trained to entirely new levels
of durability through electrical stimulation. With sufficient stimula-tion,
skeletal muscle cells can be made to contract more like heart muscle cells.  

"Heart transplantation is very successful at the centers that do it well,'
Guilbeau adds.  "However, the bottom line is that there just are not enough
donor hearts to go around. The idea of taking skeletal muscle--such as a
portion of the back's latissimus dorsi--and converting it from muscle that is
easily fatigued into a cardiac-like muscle which beats continuously, really is
an elegant solution to repairing injured hearts"

"Skeletal muscle needs to be activated in some way, usually via an electrical
--------- end of part 3 ------------


Fri, 22 Sep 1995 03:52:26 GMT
 [ 1 post ] 

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