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National Institutes of Health (U.S.). Division of.

Annual report : National Institutes of Health. Division of Research Grants (Volume 1981) online

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modes. This work is an extension of previous work on the axisymmetric, varicose
mode.



PHS-6040
(Rev. 2-81)



79



ZOl RS 10085-01 BEI



Objectives ; The short term objective is to develop confidence in the conceptual
model proposed here for the stimulated growth of small blood vessels. Satisfactory
comparison between theoretically predicted wavelengths for the various buckling
modes with measurements made from experiments on tumor angiogenesis would
lend credence to the ideas set forth in earlier work.

Methods Employed ; Analytical methods are used to solve the equations governing
the physical model. The nonlinear partial differential equations are solved exactly
for the case of a uniformly dilating vessel. The buckling sets in as an instability of
the slowly dilating state. The dominant wavelengths are extrated by a perturbation
analysis for each separate mode.

Significance ; With regard to tumor angiogenesis, the model gives us a framework
which helps explain the presence of tortuous and focally dilated blood vessels in the
vicinity of a tumor inplant. It seems that new capillaries sprout in the vicinity of
the wavecrests associated with buckling and thus, the buckling of preexisting
vessels is intimately related to the vascularization process of the tumor itself.

Proposed Course ; If the buckling theory continues to yield satisfactory predictions
for the wavelengths of the various modes, it can then be utilized to explore the
sprouting phenomenon. By considering the reaction-diffusion dynamics of growth
promoters and inhibitors on buckled surfaces, we hope to identify sprouting sites as
regions of enhanced promoter concentration on the vessel surface.

Publications ;

Waxman, A.M.; Blood vessel growth as a problem in morphogenesis - A physical
theory. Microvascular Research (in press).

Waxman, A.M.: A continuum approach to blood vessel growth-axisymmetric
elastic structures. 3. Theoretical Biology (in press).



80



SMITHSONIAN SCIENCE INFORMATION EXCHANGE
PROJECT NUMBER (Oo NOT use this space}



U.S. DEPARTMENT OF

HEALTH AND HUMAN SERVICES

PUBLIC HEALTH SERVICE

NOTICE OF

IMTRAHURAL RESEARCH PROJECT



PROJECT NUMBER



ZOl RS 10086-01



PERIOD COVERED



TITLE



■ |ly ?^ IQX l *r> S^ptPmhpr 30, j 9R 1

: Oi^ PRO'JECT (30 characters or less)



Theory of Lateral Diffusion in Cell Membranes



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



PI; A.M. Waxman



Physical Scientist



BEIB, DRS



COOPERATING UNITS (if any)



None



LAB/BRANCH

RinrnpHiral F.nginppring and Instrumentation Branch



SECTION

Mechanical Engineering



INSTITUTE AND LOCATION

H R S , N IH. Bethesda,



Mar yland 2Q2Q ^



TOTAL MANYEARS:

0.05



PROFESSIONAL:

0.05



0.00



CHECK APPROPRIATE BOX(£S)
G (a) HUMAN SUBJECTS

n (al) MINORS □ (a2) INTERVIEWS



□ (b) HUMAN TISSUES



(c) NEITHER



SUMMARY OF WORK (200 words, or less - underline keywords)

Lateral diffusion of proteins in cell membranes is treated as a problem in Brownian
motion through a two-dimensional viscous fluid membrane with curvature and of
finite area. Analogous to the Stokes-Einstein relation for diffusion through a
viscous bulk fluid, we seek to relate the diffusion constant of a protein in a
membrane to the rheological and geometrical properties of the membrane as well
as to the size of the protein molecule.



PHS-6040
(Rav. 2-31)



81



ZOl RS 10086-01 BEI



Objectives ; Our first objective is to calculate the hydrodynamic drag force exerted
on a protein moving through a fluid membrane of finite area which possesses finite
curvature as well. This drag force may then be utilized in a Langevin-type
approach to Brownian motion in such a membrane.

Significance; We hope to develop a physical understanding of lateral diffusion in
cell membranes. Diseased states of the membrane will affect its rheology as well
as its shape, and this should reflect itself in altered diffusion rates of proteins.
This, in turn, will influence the overall performance of the cell.

Proposed Course ; At first, the membrane is being treated as a two-dimensional
viscous fluid. In the future we hope to consider more realistic viscoelatic fluid
models for the cell membrane.



82



SMITHSONIAN SCIENCE INFORMATION EXCHANGE!
PROJECT NUMBER (Oo MOT usa this space)



U,S, DEPARTMENT OF
1 HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE
NOTICE OF
INTRAaURAL RESEARCH PfiOJECT



PROJECT NUMBER



ZOl RS 10087-01



PERIOD COVERED



July 26. 1981 to SepternhPr ^0. IQXl



TITLE OF PROJECT (80 characters or less

Mechanics of Red Blood Cells in Flow



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



PI: A.M. Waxman



Physical Scientist



BEIB, DRS



COOPERATING UNITS (if any)

None



LAS/SRANCH

Bjomed jc ai Engin e erin g a nd f astriimePt-alioo-Bcanctu



SECTION

Mechanical Engineering



INSTITUTE AND LOCATION

DRS. NIH, Bethesda. Md„ 20205



TOTAL MANYEARS:

Ool



PROFESSIONAL:

OJ



JUL



CHECK APPROPRIATE 30x(£S)
D (a) HUMAN SUBJECTS

n (al) MINORS n (a2) IMTERVIEWS



(b) HUMAN TISSUES



(c) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

The red blood cell is modeled as a fluid droplet surrounded by a viscoelastic fluid
membrane which possesses a bending resistance. The resting shape of the cell is
taken to be a biconcave disk. When the cell is immersed in a shear flow, it deforms
in shape and sets up an internal circulation as well as a membrane flow. We seek
to calculate such shapes from mechanical considerations, and relate shape and flow
to membrane rheoiogy.



PHS-6040
(Rev. 2-81)



83



ZOl RS 10087-01 BEI



Objectives ; We seek to relate red cell shape and deformability to membrane
Theology via these hydrodynamic calculations. Then, by comparing the calculated
shapes to those observed experimentally, we hope to determine the rheological
constants which characterize the mechanical properties of the lipid bilayer-
spectrin composite which forms the membrane.

Methods Employed; The formalism developed by Waxman to describe the mechan-
ics of deforming surface continua shall be utilized here. This theory of the
kinematics, dynamics, and rheology of evolving surface phases enables us to
describe the membrane flow for a deforming cell. The internal flow shall be
modeled as an incompressible viscous fluid. The governing equations must be
solved numerically.

Significance ; Various diseases states are characterized by altered mechanical
properties of the erythrocyte membrane. This manifests itself in altered deform-
ability, and this in turn affects the flow properties of blood (as a suspension of red
cells). Thus, it is important to understand the mechanics of the membrane itself
and how it relates to red cell deformability.

Publications ;

Waxman, A.M.; Dynamics of a couple-stress fluid membrane. J. Fluid Mechanics (in
press).

Waxman, A.M.; A corotational time-derivative for surface tensors, constitutive
relations, and a new measure of bending strain. 3. Non-Newtonian Fluid Mechanics
(in press).



84



SMITHSONIAN SClcNCS INFORMATION EXCHANGE U.S. DEPARTMENT OF

PROJECT NUMBER (Oo NOT use this spacs) \\ HEALTH AND HUMAN SERVICES

' PUBLIC HEALTH SERVICE

NOTICE OF
INTRAMUfiAL RESEARCH PROJECT



PROJECT NUMBER



ZOl RS 10088-01



PERIOD COVERED

OrtnhPr I. 1980 to Se ptember 30, 1981



TITLE OF PROJECT (80 characters or less)



Multimode R5232-C Data Switch



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS ANO ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



Pis C.C. Gibson



Electrical Engineer



BEIB, DRS



COOPERATING UNITS (if any)



LAB/8RANCH

Biomedical Engineering and Instrumentation Branch



SECTION

Electrical and Electronic Engineering Section



INSTITUTE ANO LOCATION

DRS . NIH, Rpthes da, Md . 70 7 0^



TOTAL MANYEARS:

0.2



PROFESSIONAL:

M



0.1



CHECK APPROPRIATE 80X(£S)
n (a) HUMAN SUBJECTS

n (al) MINORS G (a2) INTERVIEWS



Q (b) HUMAN TISSUES



a {=) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

With the advent of smart instrumentation, methods are needed to transfer the data
from the instrument to a large computer for analysis. This particular device allows
a large coulter counter to transfer its data to either an NIH 7000 terminal or to the
DEC- 10 computer without cable switching.



PHS-6040
(Rev. 2-81)



85
ZOl RS 10088-01 BEI



Objective ; To transfer data from a coulter counter to the DEC-10 computer.

Methods: This switch utilizes a diode OR-Gate so that an interactive terminal can
stay on line to the computer at the same time the Coulter counter is on line and
transfering data.

Significance ; This device enabled the researcher to process twice as many samples
per day.



86



SMITHSONIAN SCIENCE INFORMATION cXCHANGE
PROJECT NUMBER (Oo NOT yse this spaca)



U.S. DEPARTMENT OF

HEALTH ANO HUMAN SERVICES

PUBLIC HEALTH SERVICE

Notice OF

INTRAMURAL RESEARCH PROJECT



PROJECT NUMBER

ZOl RS 10089-01



PERIOD COVERED

October 1, 1980 to September 30, 1981



TITLE OF PROJECT (30 characters or less)

Non-invasive Hemoglobin iMeasurement



NAMES, LABORATORY ANO INSTITUTE AFFILIATIONS, ANO TITLES OF PRINCIPAL INVESTIGATORS ANO ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT

BEIB, DRS
Blood Bank, C.C.
Blood Bank, C.C.
Blood Bank, C.C.



PI;


C.C. Gibson


Electronics Engineer


OTHER;


H.G. Klein
S. Rosen


M.D.




V. Weber


R.N.



COOPERATING UNITS (if any)

Blood Bank. Clinical Center



LAB/BRANCH

Biomedical Engineering and Instrumentation



SECTION

Electrical and Electronic Engineering Section



INSTITUTE AND LOCATION

DRS, NIH , Bethesda, Md. 20205



TOTAL MANYEARSj

i.n



PROFESSIONAL:

0.^



0.6



CHECK APPROPRIATE BOx(£S)
g (a) HUMAN SUBJECTS

D (al ) MINORS G (*2) INTERVIEWS



n (b) HUMAN TISSUES



n (=) NEITHER



SUMMARY OF WORK (200 words or less ~ underline keywords)

In the treatment of thalassemia, iron poisoning from frequent transfusions is the
primary cause of death. If neocytes only are transfused then the frequency of
transfusions is cut by half. To collect neocytes, a method was needed to
continuously monitor the hemoglobin concentration of the output of an IBM
continuous flow cell separator. A device was designed and built that continuously
measures hemoglobin concentration non-invasively . The sensor head fits over the
output tube and uses optical methods to measure the hemoglobin concentration.
The device will measure from 0-12g% concentration with less than .3g% error.



PHS-6040
(Rev. 2-81)



87



ZOl RS 10089-01 BEI



Objectives ; To measure hemoglobin concentration from l.g% to 5.0g% non-
invasively and continuously.

Methods Used ; Optical density measurements are done using optical feedback
through the solution being measured. The device is slipped over the output tube of
the IBM continuous flow cell separator making it completely non-invasive.

Significance ; This device aids in the collection of neocytes and allows the operator
of the cell separator to keep the interface essentially constant.

Proposed Course ; To more fully calibrate the instrument and prepare a publication.



SMITHSONIAN SCIENCE INFORMATION EXCHANGE
PROJECT NUMBER (Oo MOT us« this space)



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HEALTH AND HUMAN SERVICES

PUBLIC HEALTH SERVICE

NOTICE Of

IHTRAKURAL RESEARCH PtiOJSCT



PROJECT NUMBER
ZOl RS 10090-01



PER 1 00 COVERED

October 1, 1980 to September 30, 1981



TITLE OF PROJECT (80 chapaciars or less)



Computer-controlled Fermentation System



NAMES, LABORATORY ANO INSTITUTE AFFILIATIONS, ANO TITLES OF PRINCIPAL INVESTIGATORS ANO ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



PI:
OTHER!



T.R. Clem, Sr.
Yossi Shiloach



Electronic Engineer
Chief, Power Plant Unit



EEES,BEIB, DRS
LNE NIADDK



COOPERATING UNITS (if any)

LNE, NIADDK



LAB/SRANCH

Biomedical Engineering and Instrumentation



SECTION

Electrical and Electronic Engineering



INSTITUTE ANO LOCATION

DRS. NIH. Bethesda. Md, 20205



TOTAL MANYEARSi

0.3



PROFESSIONAL:

0.2



OTHER:



0.1



CHECK APPROPRIATE 30X(ES)
D (a) HUMAN SUBJECTS

D (al) MINORS G (a2) INTERVIEWS



n (b) HUMAN TISSUES



K} (c) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

A computer controlled fermentation system is being developed for monitoring and
controlling the fermentation process. The system will be assembled using primarily
commercial instruments interconnected via the IEEE-f88 GPIB. This approach will
allow scaling the process to different size vats with a minimum of changes
required.



PHS-6040
(Rev. 2-31)



89



ZOl RS 10090-01 BEI



Objectives; Design and implement an instrumentation and control system to allow
monitoring and control of the fermentation process in any of several fermentation
vats.

Methods Employed; The first system to be assembled will consist of some
instruments which were already in use in the pilot plant and some instruments
which were purchased specifically for this project, all connected to an inexpensive
desk-top computer. The computer is programmible in BASIC, which allows the
experimenter to easily produce the controlling and monitoring programs. Most all
interconnections to the computer will be via the lEEE-'fSS GPIB.

Significance: Computer monitoring and controlling of the fermentation process
will produce several significant advantages over the present methods. By using the
computer to make decisions based on what is occuring in the fermentation process,
parameters can automatically be altered to produce either an increased yield of a
desired product or a more pure form of the product. The computer can also
perform some of the "housekeeping" tasks associated with running a fermentation
process that would normally require an operator.

Proposed Course ; To assemble a basic system to begin controlling and monitoring a
fermentation process to determine where further effort or refinement is necessary.



90



SMITHSONIAN SCIENCE INFORMATION EXCHANGE
PROOECT NUMBER (Oo NOT us« this space)



U,S. DEPARTMENT OF
1 HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE
NOTICE OF
NTRAMURAt. RESEARCH PROJECT



PROJECT NUMBER



ZOl R5 10091-01



PERIOD COVERED

October 1, 1980 to September 31. 1981



TITLE OF PROJECT (80 eharacisps or less)

Mechanics of Red Blood Cell Membrane



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



Pis D„R. Markle



Biomedical Engineer



BEIB, DRS



COOPERATING UNITS (if any)



lab/branch

Biomedical Engineering and Instrumentation Branch



SECTION

Mechanicai F.npinppring



INSTITUTE AND LOCATIf

DRS, NIH, Bethesda, Md. 20205



TOTAL MANYEAfiS:

L



PROFESSIONAL;



CHECK APPROPRIATE BOX(£S)
S (a) HUMAN SUBJECTS

D (al) MINORS n (a2) INTERVIEWS



n (b) HUMAN TISSUES



n (c) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

a micromanipulation system consisting of an inverted microscope, two micro
manipulators and video equipment necessary for the recording and analysis of
data has recently been acquired. This system will be used to investigate the
intrinsic material properties of red cell membrane and large lipid vesicles
using micropipette aspiration and flow channel techniques.



PHS-6040
(Rev. 2-81)



91



ZOl RS 10091-01 BEI



Methods : Presently both micropipette aspiration and slow channel techniques
are being developed and will be used in the above studies. However, the system
is flexible and can be readily adopted to the needs of any specific experiment.

Proposed Course ; Initially the system will be used to investigate the intrinsic
material properties of red cell membrane in diseased states. At the present
time red blood cells obtained from diabetics are of primary interest. However,
red cells from patients with sickle cell anemia and muscular dystrophy etc. are
also of interest and will be studied. Other uses of this system may include studies
of cell lysis during the freezing and thawing process used in blood storage, measurement
of the affinity of red blood cell membranes for particle surfaces, and measurements
of the mechanical properties of both pure and multiphase vesicle systems.



92



SMITHSONIAN SCIENCE INFORMATION EXCHANGE,
PROJECT NUMBER (Do NOT use this spaca)



U.S. DEPARTMENT OF
1 HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE
HOTlCe Of
INTRAMURAL RESEARCH PROJECT



PROJECT NUMBER
ZOl RS 10092-01



PERIOD COVERED



October 1 , 19Rn fn Spptpmhpr ^ 0, 19X1



TITLE OF PROJECT (SO characters or less)

Low Duty Cycle, Pulsed Electromagnetic Blood Flowmeter



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



Hs



C.P. Mudd
R. Patterson



Biomedical Engineer
Senior Investigator



MES, BE!B, DRS
Cardiology, NHLBI



COOPERATING UNITS (if any)

Cardiology Branch, NHLBI



LAB/BRANCH

BEIB



SECTION

MES



INSTITUTE AND LOCATION

DRS. NIH. Bethesda, Md. 20205



TOTAL MANYEARSj

0.2



PROFESSIONAL:

OJ



CHECK APPROPRIATE BOX(ES)
G (a) HUMAN SUBJECTS

D (al) MINORS a (a2) INTERVIEWS



Q (b) HUMAN TISSUES



(c) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

To design, construct, and evaluate a prototype of a low duty cycle pulsed
electromagnetic blood flometer . The design will use an excitation scheme which
will simplify probe construction and also increase reliability .



PHS-6040
(Rev. 2-31)



93



ZOl RS 10092-01 BEI



Objective ; By using a pulsed excitation scheme, it is possible to eliminate the
quadrature voltage problem. Without the quadrature signal, we can simplify the
probe design and thus produce a more reliable instrument.

Significance; If we use A.C. excitation in an electromagnetic flowmeter, a
quadrature voltage, E is created which is generally orders of magnitude greater in
amplitude than the flc^-induced signal. In practice, to reduce E , the probes are
partially assembled and when excited, the electrode leads are moved to reduce E .
The probes are then encapsulated. Because of this procedure, the probe cost vs
high, $300/unit, and any subsequent change in the capacitive or inductive voltages
will upset the nulled condition and increase E thus rendering the probe useless. If
the above scheme can be implemented, this problem will be eliminated.

Proposed Course ; (1) Design the signal amplifier and associated circuits; (2) Design
a pulse amplifier to drive the probes; (3) Redesign the probe to ensure that the
magnetic field is constant across the lumen.



94



SMITHSONIAN SCIENCE INFORMATION EXCHANGE
PROJECT MUMBEfi (Do HOT use this space)



U,S. DEPARTMENT OF
1 HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE
Notice OF
inrRAMURAL RESEARCH PflOUECT



PROJECT NUMBER



ZOl RS 1009^-01



PERIOD COVERED

October L 1980 to September 30. 1981



TITLE OF PROJECT (80 characters or less)

Removal of Atherosclerotic Plaque from Arterial Walls Using A Special Purpose
Catheter ,



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



PI:

OTHER;



S.Ro Goldstein
K. Kent



Chief
Chief



MES BEIB DRS
CDSCBNHLBI



COOPERATING UNITS (if any)

Cardiovascular Diagnosis Section, Cardiology Branch, NHLBI



lab/branch

Biomedical Engineering and Instrumentation Branch



SECTION

Mechanical Engineering



INSTITUTE AND LOCATION

NatkmaiIastitu£es-af-HeaJ t .h..B e thfts d a , M P 2 Q 2 Q5

TOTALMANYEARST^ | OTHER:



CHECK APPROPRIATE BOX(£S)
n (a) HUMAN SUBJECTS

n (al) MINORS (i2) INTERVIEWS



(b) HUMAN TISSUES



n (=) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

A variety of concepts will be investigated to determine the feasibility of developing
a special purpose catheter to removed arterial plaque from coronary vessels.
Use of lasers, ultrasonics, and mechanical means will be evaluated as appropriate.



PHS-6040
(Rav, 2-81)



95



ZOl RS 10094-01 BEl



Objective : To conceive and determine the feasibility of various techniques of
removal of plaque from arterial wall.

Significance ; The development of a technique for removal of plaque via a catheter
would aleviate the need for open chest surgery in some cases, and allow treatment
in other cases where such surgery cannot be done. This would be of great importance
in the treatment of coronary artery disease.

Proposed Course ; a) Conceive of and evaluate concepts for plaque removal; where
appropriate perform critical experiments, b) develop a miniature fiber optic
imaging catheter to visually examine coronary vessels.



SMUHSONIAN SCIENCE INFORMATION EXCHANGE
PROJECT NUMBER (Oo NOT use this spaco)



U.S. DEPARTMENT OF
1 HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE
NOTICE OF
iHTRAtlUfiAt. RESEARCH PROJECT



PROJECT NUMBER



ZOl RS 10095-01 BEI



PERIOD COVERED



October 1, 1980 to September 30, 1981



TITLE Of PflOJECT (80 characlers or less)

Multiple Probe pH Measurement System for Canine Myocardium



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



PI:

OTHER:



D. Markle
D. McGuire
S. Goldstein
R. Patterson



Biomedical Engineer

Mathematician

Chief

Senior Investigator



MES BEIB DRS
MES BEIB DRS
MES BEIB DRS
NHLBI



COOPERATING UNITS (if »ny)

Cardiology Branch, NHLBI



lab/ BRANCH , ^

Biomedical Eng



inering and Instrumentation



SECTION

Mechanical Engineering



INSTITUTE AND LOCATION

Natio nal Institutes of Health, Bethesda, MP 20205



TOTAL MANYEARSi
1.5



PROFESSIONAL!
1.5



OTHEfii



CHECK APPROPRIATE BOX(ES)
□ (a) HUMAN SUBJECTS

n(al) MINORS Q (a2) INTERVIEWS



D (b) HUMAN TISSUES



|S\.{c) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

For the past several years, considerable effort has been expended on the development
of a miniature fiber optic pH probe for physiological use. With the first generation
of probes and support equipment the feasibility of optically measuring pH via
a pH sensitive dye was demonstrated and many subtleties associated with the
probe construction and use made apparent. With this knowledge and experience
and improved probe and multichannel support system has been designed and
constructed and is presently being used to measure pH in the wall of beating
canine hearts.



PHS-6040
(Rtv. 2-81)



97

ZOl RS 10095-01 BEI



Objectives ; To provide a pH probe which was rugged, easily and atriumatically
Inserted into a beating heart, free from motion artifacts, quick to respond to pH
changes and able to resolve pH with a spatial resolution of approximately 0.5mm.
Furthermore the support system was required to provide continuous data (visual
and hard copy) for each of five probes.

Methods Employed ; The probe was redesigned to fit into a 25 gauge (0.5mm
diameter) stainless steel needle by reducing the diameters of the optical fibers to
0.075mm and the inside diameter of the semi-permeable membrane is provided by
two slots machined in the needle wall and a transverse hole 0.368 mm in diameter.
This design increased the probes* durability and eliminated all motion artifacts. In
addition, the smaller probe dimensions reduced the insertion trauma and decreased
the 90% step-response time from approximately 90 to 30 seconds. The spatial
resolution of the probe was increased by concurrently reducing the dye column
length to 0.12 mm and terminating the column with a reflective surface. The
mirror surface is required to avoid excessive light loss through the end of the dye
column.

Significance ; At the present time this is the only system available to measure
tissue pH in-vivo and on line. Such information is of use to experimental
cardiologists interested in evaluating drugs which affect tissue perfusion, obstetri-
cians interested in monitoring fetal scalp pH and biomedical researchers in general.

Proposed Course ; To further improve the reliability and ease of operation of the
system and to reduce its size and cost.



98



SMITHSONIAN SCIENCE INFORMATION EXCHANGE


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