Collaborative
Study
of Children
Treated
for
Phenylketonuria:
Study
Design
Malcolm Williamson, Ph.D., James C. Dobson, Ph.D., and Richard Koch, M.D.
Writing Committee for the PK U Collaborative Study
ABSTRACT. Studies that have attempted to test the effec-tiveness of treatment in phenylketonunia (PKU) have been handicapped by small samples due to rarity of the disorder and inadequate control of other sources of error. The present study was designed to overcome these limitations by treating
a large number of children with PKU under controlled conditions from near birth to 6 years of age. Nineteen medical centers in 13 states have participated in the study, which is currently in progress. This article is one of a series of
final reports. It describes the study design and sampling procedures employed to answer questions of interest for
which results will be reported in subsequent articles. The study serves as a model for future collaborative investigations of a similar nature. Pediatrics 60:815-821, 1977,
PHENYLKETO-NURIA, COLLABORATIVE INVESTIGATIONS.
A longitudinal collaborative study was
insti-tuted in 1967 to test the effects of dietary restriction of phenylalanine in the treatment of phenylketonuria (PKU). This article, one of several final reports, documents the need for the study, summarizes its historical development, outlines its scope, presents the study design, and describes the sample selection procedure and methodology.
NEED FOR THE STUDY
When the study was conceived, results from
clinical and scientific research were definitive in some areas of investigation and conflicting or inconclusive in other areas. There was general agreement that PKU is an inborn error of metab-olism expressed by the defective functioning of the enzyme, phenylalanine hydroxylase, in the Ii-ver.’’ The absence or inactivity of this enzyme
was known to result in accumulations of phenyl-alanine and its metabolites in body tissues and
fluids.4 Sustained high levels of phenylalanine in blood were known to be related to impaired
cognitive ability, although the explanatory mech-anisms of this relationship were unknown.5 The initial report of an effective treatment6 was
followed by a plethora of studies by individual
investigators purportedly designed to test the effects of dietary restricted phenylalanine.
Conclusions from many of these studies left the distinct impression that they were based on definitive evidence.58
Subsequently, certain scientists’2 16 challenged the interpretations drawn from these studies. Some of them merely registered doubts about the apparent benefits of treatment,’2’4 while others were convinced that treatment was
ineffec-16 One of the severest critics of early
research presented plausible arguments suggest-ing that the “deprivation diet” actually could be
harmful to both physical growth and intellectual development, at the same time masquerading as “successful” 16
As the controversy grew, concern developed that patients with PKU would not receive appro-priate medical care. On the one hand, claims of
fi
nal evidence and conclusive proof regarding the benefits of treatment do appear to have been premature. Conversely, if proper treatmentindeed would allow all children with PKU to
Received November 24, 1976; revision accepted for
publica-tion March 28, 1977.
Supported by grant MCT-000466 from the Bureau of Community Health Services, Health Services Administra-tion, U.S. Department of Health, Education and Welfare.
ADDRESS FOR REPRINTS: (MW.) PKU Collaborative
Study, 4650 Sunset Boulevard, Childrens Hospital, Los
attain, or approximate, their expected levels of
physical, cognitive, and psychosocial
develop-ment, then there was an urgent need for valid evidence to establish this fact. Individuals on both
sides of the controversy acknowledged that a
collaborative investigation was needed to solve the problem. This viewpoint is reflected in the following statement issued in 1965 by the Committee on Handicapped Children, American Academy of Pediatrics’2:
Much more data, taking into account all the known
variables, must be accumulated and carefully analyzed
before definitive statements can be advanced regarding the precise value of diet in preventing or ameliorating phenIke-tonuria. This will require considerable time. A collaborative
study to evaluate managenient of this disease would be
valuable.
A longitudinal investigation was also required to
ascertain optimal levels of maintenance between phenylalanine deficiency on one hand, and
intel-lectual retardation from high phenylalanine levels
on the other.
HISTORICAL DEVELOPMENT
Plans for the present study began to emerge in 1965, subsequent to the development of a reliable and inexpensive screening procedure for PKU.’7
Within a short time, 40 states had enacted laws
requiring routine blood screening of newborns. These events enhanced prospects that a collabo-rative study would provide a sample sufficiently large and representative to permit the research findings to have general application in the treat-ment of PKU, thereby overcoming a major limita-tion that had hampered individual investigators. Three planning conferences held in Washington, D.C., in 1965, 1966, and 1967 contributed
substantially to the development of a workable
study protocol which served as a proposal for a grant request submitted to the Children’s Bureau of the Department of Health, Education and
18
SCOPE OF THE STUDY
The present study was designed to answer
fundamental questions about the efficacy of
dietary therapy in the treatment of PKU. The
principal question was, “What are the effects of
diets restricted in phenylalanine on the physical,
cognitive, and psychosocial development of
chil-dren with PKU?” A random assignment of chil-dren with PKU to treated vs. untreated groups
would have provided the most efficient approach
to this problem. However, it was ethically impos-sible to formulate an untreated sample, because of the claims of dietary benefit by prior
investiga-tors. Instead, a less effective design was formu-lated, permitting the comparison of children with
PKU with their nonaffected siblings. If dietary therapy is completely effective, children with PKU treated prospectively from near birth should
be comparable with their nonaffected siblings and other normative samples on variables tested. An important secondary question was, “Does dietary control of serum phenylalanine at low vs. moderate levels result in different outcomes?” If so, then groups of children with PKU treated
prospectively at these two levels should be different on variables tested. I additipn to these
questions, relationships were examined between outcomes and sex, age, socioeconomic level, and other selected factors.
The investigation of these questions required data for variables outlined below within the three areis of interest:
I. Physical criteria A. Growth
B. Neurological development
C. General health D. Biochemistry
E. Nutrition
II. Cognitive criteria
A. Intellectual development B. Linguistic ability
C. Perceptual ability D. Academic achievement III. Psychosocial criteria
A. Social, economic, and education
sta-tus
B. Family composition and living
condi-tions
C. Initial parental reaction to the PKU diagnosis
D. Parents’ intellectual ability
E. Family interaction, parent attitudes, and parent-clinic professional staff
relationships
The instruments being used to evaluate each of these areas of investigation are listed on the
Schedule of Assessments, Table I. Most of the data
relating to psychosocial criteria will be obtained
by use of questionnaires and tests created specifi-cally for the Collaborative Study.
STUDY DESIGN
The design of the study refers to the procedures
employed for the participation of medical centers, the selection of subjects in the sample, and their assignment to groups that received specific treatments.
TABLE I
SCHEDULE OF A55E55SIENT BY TYPE OF OBSERVATION AND INSTRUMENT#{176}
Type of Observation Instrument or Unit of
Measurement
Sc! iedule of Assessment
‘
,‘-Diagnosis’ 6 1 2 4 5 6
mo yr yr yr yr jr yr
Physical Nominal 5-point scale22 X X X X
Neurological Ordinal 5-point scale22 X X
Electroencephalographic Ordinal 7-point scale22 X X X
Growth in height cm22 X X X X X X X X
Growth in head circumference cm22 X X X X X X X X
Growth in weight kg22 X X X X X X X X
Hemoglobin g/100 ml2T X
Hematocrit Packed cell volume %27 X
Parental height cm22 X
Parental weight kg22 X
Parental intelligence Wechsler Adult Intelligence Scale2”
X
Socioeconomic Social Work Instrument 122 X X X X X X X
Social work assessment Social Work Instruments II,
III, & IV22
X X X X
Perception Frostig Developmental Test
of Visual Perception2
X
Neurological development Bender Gestalt with Koppit
Scoring
X
Verbal ability Mecham Verbal Language
Test32
X X
Intelligence Stanford-Binet Intelligence
Test3 .o
X X X X
Psycholinguistic ability Illinois Test of
Psycho-linguistic Ability’
X
Academic achievement Wide Range Achievement
Test ‘
X
#{176}From Koch et al.22
state that conducted routine screening of
newborns for PKU, (2) willingness of the clinic
directors to fulfill protocol requirements, and (3)
acceptance and sanction of the protocol by the collaborating agencies’ research committees.
Nineteen centers, representing major geographic
areas in the United States, met these criteria and
their directors elected to participate. Participants are listed in the Appendix. (Four of the original 19 clinics have discontinued their participation in
the study, leaving 15 currently active clinics.)
The sampling procedure attempted to
repre-sent three different populations: children with PKU who were treated prospectively from near
birth, siblings with PKU who were untreated, and nonaffected siblings of the treated children.
The prospectively treated index children with
PKU met the following criteria for acceptance in
the sample while on a normal diet: a presumptive
positive screening test performed according to
the state’s routine newborn screening program for
PKU; two determinations of serum phenylalanine
level at or above 20 mg/100 ml by the
McCaman-Robins fluorimetric procedure19 from two blood
specimens drawn at least 24 hours apart, and,
from the same blood specimens, two
determina-tions of serum tyrosine level below 5 mg/ 100 ml
by the Waalkes and Udenfriend procedure20; the
presence of phenylalanine arid its metabolites in
urine such as o-hydroxyphenylacetic acid and
phenylpyruvic acid at levels “markedly” above
normal by quantitative two-dimensional paper
chromatographic procedures21’22; receipt of par-ental permission for the child to be studied and
initiation of treatment by 121 days of age; and confirmation of the tentative diagnosis by positive
results from two challenges. The challenge
procedures (see pamphlet published by the U.S. Department of Health, Education and Welfare)
TABLE II
SUBJECTS ORIGINALLY SELECTED IN THE SAMPLE BY Gnou ASSIGNMENT AND SEX
Group Assignment
Males
No. of Subjects
Females
-. Total
Treatlnent groups
TG1 60 52 112
TG2 64 40 104
Subtotal 124 92 216
Control groups
CGJ 4 5 9
CG2-1 55 50 105
CG2-2 55 59 114
Subtotal 114 114 228
Total 238 206 444
tentative diagnosis and after 1 year of age. Infants who met the requirements for a tenta-tive diagnosis of PKU were assigned to one of two treatment groups, TG1 or TG2. All assignments to the two treatment groups were made from a table of random numbers by the project staff in telephone contact with the local clinic staff.
Children who were initially assigned to a
treat-ment group who subsequently failed challenge criteria were excluded from analyses that tested
hypotheses, although they often continued to
follow other procedures in the protocol at the
discretion of the clinic director.
Siblings of the children with PKU who were treated comprised two control groups, CG 1 and CG2. Subjects in CG1 were untreated children with PKU who were the older siblings of “index” patients in one of the treatment groups, and their diagnosis of PKU occurred subsequent to the identification of the younger child. The criteria for the selection of the children with PKU in CG 1 were the same as those for children assigned to the two treatment groups. Children in CG2 were nonaffected siblings of “index” patients with
serum phenylalanine levels in the normal range from 1.0 to 4.0 mg/100 ml and serum tyrosine levels below 5 mg/
100
ml. Also included in this group were nonaffected siblings born after the identification of index cases.The procedures for selecting the sample and assigning patients to groups constituted the major features of the study design, as shown below:
Treatment group 1 (TG 1): Patients with PKU whose serum phenylalanine level was targeted for control between 1.0 and 5.4 mgI lOOm!
Treatment group 2 (TG2): Patients with PKU whose serum phenylalanine level was
targeted for control between 5.5 and 9.9 mg/ lOOm!
Control group 1 (CG1): Siblings with PKU who were previously untreated
Control group 2 (CG2): Siblings without PKU
METHODS
Description of Sample
The assignment of index children with PKU to groups began on October 1, 1967, and ended five
years later on October 1, 1972. Sample selection
continued two additional years for the nonaf-fected siblings of the index children. Thus, acqui-sition of the total sample was complete on October 1, 1974.
Table II shows the distribution of subjects by group and sex. In the two treatment groups there were 32 more males identified than females. The difference between the proportions of males and females was not statistically significant (P >
.05).
The number of children originally assigned to CG1 was only nine. Obviously, the miniscule CG1 sample was too small to be considered represen-tative of a hypothetical “untreated” population, and no definitive conclusions could be drawn from this aspect of the study.
In Table II, CG2 children with index siblings
assigned to TG1 are identified as CG2-1, and
those with index siblings assigned to TG2 are identified as CG2-2.
The total number of subjects accepted into the
study for all groups was 444, which included 216
children selected for study in two treatment groups, 9 assigned to CG1, and 219 nonaffected siblings in the two control groups.
Management of Dietary Treatment
Management of the diets of the treated patients with PKU was accomplished by prescription of phenylalanmne
and
by nutritional guidelines forother foods. The principal source of protein in the diets of the treated patients was Lofenalac. The objective of management was to provide optimal intake of phenylalanine, protein, calories, and other nutrients for age and weight; to ensure adequate growth; and, at the same time, to control serum phenylalanmne levels within the limits specified by treatment group assignment.
The general procedure for deriving a dietary prescription required several steps. First, the
foods supplemented the formula to complete the total phenylalanine and protein requirement. Fourth, calories from nonprotein sources were used if necessary to maintain caloric needs without exceeding phenylalanine needs. Specific procedures and calculations for restricted phenyl-alanine diets for individual patients will be described in subsequent articles.
Monitoring
This section describes procedures for the measurement of nutrient intake and evaluation of serum phenylalanine levels and the measurement of physical, cognitive, and psychosocial factors according to a schedule of assessment.
Monitoring of nutrient intake was conducted in the following manner. Parents were given diet
diary forms on which they were asked to record
the names and amounts of all foods that their treated child ate for a period of three consecutive
days. These diet diaries were submitted at least
once a month, but in many cases once a week,
throughout the first year of life. The diet diaries also requested parents to report the child’s
weight, illness, and type of any medication given. On the morning of the fourth day, blood was obtained and forwarded to the local laboratory for determination of phenylalanine level. The diet diaries and blood phenylalanine level results were
forwarded to the Central Data Bank where each
food item was coded, using codes from the U.S. Department of Agriculture handbook 8,21 and then keypunched for computer analysis. The computer analysis24 summarized selected nu-trients in the form of mean amounts of intake per day and mean intake per kilogram per day. The nutrients that were summarized included phenyl-alanine, calories, protein, fat, carbohydrates, calcium, phosphorus, vitamin A, thiamine, ribo-flavin, niacin, and ascorbic acid. The nutritionist and physician evaluated the mean intake data in relation to serum phenylalanine levels as a basis for deciding to continue, or change, the dietary prescription. Records of these changes also were stored in the Central Data Bank, located at the Project Center, for analysis later with other variables.
One objective of dietary management was the control of serum phenylalanine levels within the limits specified by treatment group assignment. These limits were defined by indices of dietary control (IDC) rather than by individual serum phenylalanine determinations. The indices of dietary control were defined as (1) the median value of previous individual determinations,
IDC-1; and (2) a trapezoidal approximation of mean area under a curve of determinations plotted over
time, IDC-2. Each of these indices was calculated by special computer programs for separate
con-secutive six-month periods and for cumulative
bimonthly periods.
In addition to the monitoring schedule for nutrient intake and level of phenylalanine in blood, monitoring of outcomes was accomplished
by obtaining measurements for physical,
cogni-tive, and psychosocial variables according to the schedule presented in Table I.
The nonaffected siblings in CG2 followed the same schedule for monitoring outcomes as did treated patients except for the initial assessment
battery. An intelligence test was administered to
children in CG2 during the first evaluation, provided they were of sufficient age, whereas infants with PKU were given an EEG. Otherwise both groups received an initial battery that included standard diagnostic blood evaluations, a
physical examination, growth measurements, and
quantitative two-dimensional paper
chromatog-raphy for amino acids and phenolic acids in
urine.
Collection, Management, and Analysis
of Data
The procedure for verifying and controlling the
accuracy of the data was specific for each crite-non. A blood reference laboratory was established
to ensure the accuracy of the laboratory methods
used by local clinics to determine phenylalanine
and tyrosine levels in blood. Another reference
laboratory performed all measurements of the
metabolites of phenylalanine in urine for diag-nostic and challenge purposes.22 (Procedures implemented in the two reference laboratories will be detailed in subsequent publications.) EEGs were read at the local clinic and at the Project Center. Discrepancies between these two
readings required a “blind” reading by a third
encephalographer.22 The Committee for the Quality Control of Psychological Data developed procedures that verified the scores and other data obtained on all cognitive ability tests. Nutrient intake, biochemical data, growth measurements, and cognitive ability test scores were analyzed for outliers by a computer program.25
Analyses of the data involved descriptive, correlative, and comparative statistical pro-cedures that were appropriate for answering the
questions of interest to the study. Most of these
procedures have been written in computer language and were available through program packages, such as Biomedical Computer Pro-grams25 or the Statistical Package for the Social Sciences.26 For purposes of the study, the null hypothesis of no difference was rejected by a significance probability level of 5% or less. Procedures for maintaining the significance level (alpha) at 5% for a priori and a posteriori compar-isons among means will be described in subse-quent individual reports as they apply to specific
analyses.
Preliminary analyses of the data were conducted annually and were presented at annual conferences of participants. On the basis of these
preliminary findings and the experience gained
during the preceding year, decisions were made regarding the course of the study for the ensuing
12 months.
Despite the longitudinal nature of the PKU project, cooperation and diligence among partici-pants have been remarkably consistent. As of October 1, 1976, more than 95% of the data requested for active patients with PKU had been received by the Central Data Bank; less than 1% of the data were considered irretrievable. Appre-ciation is expressed to the
200
professionals who have contributed to this achievement, as well as to the children being studied and their parents.DISCUSSION
The present study was designed to rectify many inadequacies of earlier research, which had attempted to investigate the effects of dietary restriction of phenylalanine in the treatment of PKU. It provides the largest sample of subjects with PKU ever to receive prospective uniform treatment and evaluation from infancy. The number and type of variables measured will supply the Central Data Bank with data that will permit most of the original questions, plus numerous others, to be answered with confidence.
Although comparisons between the treated
chil-dren and their untreated siblings cannot be made, due to the small number of children in the latter
group, the major question of the causal effect of treatment on intelligence will be answerable in other ways. This evidence will be supplied, for example, if the distribution of IQs for the treated children is symmetrical and compares with mean and SD values for the population of nonaffected
children on standardized IQ tests. It will also be
supported by diminishing numbers of children
with PKU who require custodial care because they are mentally retarded.
The study applied certain principles that were
intended to provide an effective strategy for answering research questions about the effects of
treatment in PKU. To the extent that these principles prove their value for reaching the objectives, they may also be useful to collabora-tive investigations in the future.
REFERENCES
1. Kaufman S: Phenylalanine hydroxylase cofactor in
phenylketonuria. Science 128: 1506, 1958.
2. Jervis GA: Studies of phenylpyruvic oligophrenia: The
position of the metabolic error. J Biol Chem
169:651, 1947.
3. Jervis GA: Phenylpyruvic oligophrenia: Deficiency of
phenylalanine oxidizing system. Proc Soc Exp Biol Med 82:514, 1953.
4. Jervis GA, Block RJ, Bolling D, Kanze L: Phenylalanine content of blood and spinal fluid in phenylpyruvic oligophrenia. J Biol Chem 134:105, 1940.
5. Knox WE: An evaluation of the treatment of phenylke-tontiria with diets low in phenylalanine. Pediatrics 26:1, 1960.
6. Bickel H, Gerrard J,Hickmans EM: Influence of phenyl-alanine intake on the chemistry and behavior of a phenylketonuric child. Acta Paediatr 43:64, 1954.
7. Lyman FL (ed): Phenylketonuria. Springfield, Ill, Charles C Thomas Publisher, 1963.
8. Bickel H, Hudson F, Woolf L (eds): Phenylketonuria and Some Other Inborn Errors of Amino Acid
Metabo-lism. Stuttgart, West Germany, Georg Thieme
Verlag, 1971.
9. Woolf L, Griffiths R, Moncrieff A: Treatment of phenyl-ketonuria with a diet low in phenylalanine. Br Med
J 1:57, 1955.
10. Search for phenylketonuric infants, editorial. N Engl J
Med 267:212, 1962.
11. Campbell DT, Stanley JC: Experimental and
Quasi-Experimental Designs for Research. Chicago,
Rand-McNally & Co, 1963.
12. Committee on the Handicapped Child: Statement on
treatment of phenylketonuria. Pediatrics 35:499, 1965.
13. Kleimnan DS: Phenylketonuria, a review of some defi-cits in our information. Pediatrics 33:123, 1964.
14. Cooper JD: More problems of instant medicine.
Saturday Review, June 3, 1967, pp 56-61.
15. Birch HG, Tizard J: The dietary treatment of
phenylke-tonuria not proven? Dev Med Child Neurol 9:9,
1967.
16. Bessman SP: Legislation and advances in medical
knowledge: Acceleration or inhibition? J Pediatr 69:334, 1966.
17. Guthrie R, Susi A: A simple phenylketonuria screening
method for newborn infants. Pediatrics 32:338,
1963.
18. Koch R, Dobson J, Williamson M: Research Design for the Collaborative Study of Children Treated for Phenylketonuria, ed 4. Los Angeles, Childrens Hospital of Los Angeles, 1967.
19. McCaman MW, Robbins E: Fluorimetric method for
the determination of phenylalanine in serum. JLab Clin Med 59:885, 1962.
estimation of tyrosine in plasma and tissues. J Lab Clin Med 50:733, 1957.
21. Blaskovics ME, Shaw KNF: Hyperphenylalaninemia:
Methods for differential diagnosis, in Bickel H,
Hudson F, Woolf L (eds): Phenylketonuria and
Some Other Inborn Errors of Amino Acid
Metabo-lism. Stuggart, West Germany, Georg Thieme
Verlag, 1971, pp 98-102.
22. Koch R, Dobson J, Williamson M, et at: Research Design for the Collaborative Study of Children Treated for
Phenylketonuria, ed 7. Los Angeles, Childrens
Hospital of Los Angeles, 1970.
23. Watt BK, Merrill AL: Composition of Foods, handbook 8. US Dept of Agriculture, 1963.
24. Williamson M, Azen C, Acosta P: A computerized
procedure for estimating nutritional intake. J
Toxicol Environ Health 2:481, 1976.
25. Dixon WJ: Biomedical Computer Programs. Los
Angeles, University of California Press, 1970. 26. Nie N, Bent D, Hull C: Statistical Package for the Social
Sciences. New York, McGraw-Hill Book Co Inc,
1970.
27. Coulter 5: Standard Laboratory Procedure.
Unpub-lished.
28. Wechsler D: Wechsler Adult Intelligence Scale. New
York, The Psychological Corp, 1955.
29. Frostig M: Developmental Test of Visual Perception, ed
3. Palo Alto, Calif, Consulting Psychologists Press mc, 1963.
30. Bender L: A Visual Motor Gestalt Test and Its Clinical
Use. New York, American Orthopsychiatric Assoc,
1938.
31. Koppitz EM: The Bender Gestalt Test for Young
Chil-dren. New York, Grune & Stratton, 1963.
32. Mecham MJ: Verbal Language Development Scale.
Circle Pines, Minn, American Guidance Service
Inc, 1958.
33. Terman LM, Merrill MA: Stanford-Binet Intelligence Scale. Boston, Houghton Mifflin Co, 1963.
34. Thomdike RL: Stanford-Binet Intelligence Scale 1972
Norms Tables, form LM. Boston, Houghton Miffhin
Co, 1972.
35. Kirk 5, McCarthy JJ, Kirk WD: Illinois Test of Psycho-linguistic Abilities. Urbana, Ill, University of Illi-nois, 1968.
36. Jastak J: Wide Range Achievement Test. Wilmington, Del, Charles L Story Co, 1946.
ACKNOWLEDGMENT
Appreciation is expressed to the Publications Committee, Drs. N. Holtzman (Chairman), P. Acosta, H. Berendes, E.
Layne, and M. O’Flynn, for their constructive criticisms and editing of the several drafts of this article; to Mrs. Rita Kelly and Miss Mary Lorraine Chase for their typing skills and patience with the authors during the period between the first
draft and the final typed manuscript; and to Mrs. Jean
Wombacher for keypunching the data.
APPENDIX
Project Staff (Division of Medical Genetics, Childrens
Hospital of Los Angeles)
George Donnell, M.D., Medical Director, 1975-1976
Richard Koch, M.D., Medical Director, 1967-1975,
1976-present
Malcolm Williamson, Ph.D., Project Co-Director
James C. Dobson, Ph.D., Project Co-Director, 1967-1976 Eva G. Friedman, B.A., Project Coordinator
Colleen Azen, B.A., Coordinator, Computer Services Emily Kushida, M.S., Biostatistician
Project Clinic Directors
Carl Ashley, M.D., #{176}Oregon Board of Health, Portland
Stanley Berlow, M.D., University of Wisconsin, and Harry
Waisman, M.D., Ph.D.,t University of Wisconsin Medical Center, Madison
James Coldwell, M.D., Childrens Medical Center, Tulsa,
Oklahoma
June Dobbs, M.D.,#{176}Milwaukee Childrens Hospital
William Frankenburg, M.D., NIH grant RR-69, University of
Colorado, Denver
Vanja Holm, M.D., University of Washington, Seattle Neil Holtzman, M.D., Johns Hopkins Hospital and Maryland
State Department of Health, Baltimore
David Hsia, M.D.,t and George Smith, Loyola
University, Maywood, Illinois
Charles Johnson, M.D., and Gerald Solomons, M.D., Iowa
University Hospitals, Iowa City
Margaret O’Flynn, M.B., Ch.B., Children’s Memorial
Hospi-tat, Chicago
Charles Parker, M.D., and Milan Blaskovics, M.D., Childrens Hospital of Los Angeles
Raymond M. Peterson, M.D., Childrens Hospital and Health
Center, San Diego
Ira Rosenthal, M.D., University of Illinois Hospital, and
Julian Berman, M.D., Chicago Medical School, Chicago Bobbye Rouse, M.D., University of Texas, Galveston
Albert Schneider, M.D., Ph.D., State University of New
York, Syracuse
Carol Shear, M.D., University of Miami, Miami, Florida
Bernice Sigman, M.D., University of Maryland School of
Medicine and Maryland State Department of Health,
Baltimore
Robert Warner, M.D., Childrens Hospital, Buffalo, New
York
Hobart Wiltse, M.D., * University of Nebraska,
Omaha
Laboratory Directors
Samuel Bessman, M.D. (Biochemistry), Serum Blood
Refer-ence Laboratory, University of Southern California, Los Angeles
Kenneth N. F. Shaw, Ph.D. (Biochemistry),
Chromato-graphic Reference Laboratory, University of Southern California, Los Angeles
Project Consultants
Phyllis Acosta, Dr.P.H. (Nutrition), University of New
Mexico, Albuquerque
Stanley Azen, Ph.D. (Biostatistics), University of Southern
California, Los Angeles
Allan Barclay, Ph.D. (Psychology), St. Louis University, St. Louis
Heinz Berendes, M.D. (Epidemiology), National Institute of
Child Health and Human Development, Bethesda,
Mary-land
Rudolph Engel, M.D. (Electroencephalography), University of Oregon Health Sciences Center, Portland
Robert Henderson, Ed.D. (Education), University of Illinois, Urbana
Alfred Katz, D.S.W. (Social Work), University of California,
Los Angeles
Ennis Layne, Ph.D. (Biochemistry), University of Southern
California, Los Angeles
Robert Podosin, M.D. (Electroencephalography), University of Southern California, Los Angeles
#{176}Clinicdiscontinued.
