A Precious Research Resource

To conduct a prospective epidemiologic study of the possible relationship of Serum Factor X to Disease Y, the serum level of Factor X first must be measured in a large group of apparently healthy people. Over the ensuing years, a small fraction of the study group will develop Disease Y. It can then be determined if Disease Y is more or less likely to occur in persons with high or low prediagnositc levels of Factor X. Clearly, prospective studies are costly, and the results are delayed by the need to wait many years for Disease Y to occur in enough persons in the study group to provide statistical reliability.

The OFAS-KP Serum Treasury -- combined with the number-identified donors' subsequent medical histories at Kaiser Permanente -- offers a unique opportunity to discover disease risk (or prevention) factors that are detectable in serum, and to do so by the quick and cost-effective method of retrospective epidemiology.

Since the first study, published in 1984, the Serum Treasury has yielded important contributions to biomedicine (see studies shown in red in the publications list). Additional significant discoveries are expected from current studies nearing completion. Recently started studies -- and others in the planning stage -- ensure a productive future for the Serum Treasury that now contains almost 500,000 frozen samples.

The following sections bring together all of the historical and contemporary facts about the Serum Treasury to create a greater awareness of this special research resource that is deserving of both contributors' support and collaborators' innovative use.

In July 1964, the KPMCP of Northern California, then serving about 18% of the population in the San Francisco Bay Area, began evaluating multiphasic health testing services for its members through the efforts of Dr Sidney Garfield and Dr Morris F Collen.

The vision of Drs. Garfield and Collen was to establish a system of regular and comprehensive, broad-spectrum physical examinations, including routine blood testing and urinalysis, with the goal of providing health maintenance through early diagnosis. This pilot program, funded by the National Institutes of Health and the Henry J Kaiser Family Foundation, was unprecedented and, at the time, cost $11,000,000.

Health, disease and epidemiologic data on all those examined were entered into the KPMCP computer.

A foresighted aspect of the program was the storage of a frozen serum sample from each person for future health maintenance and disease prevention studies.

During the years of this research project (1964-1971), some 263,000 blood serum samples were collected and stored on nearly 123,000 healthy persons undergoing the comprehensive exam. There are, on average, two samples from each serum donor in the 1964-1971 collection period.

Each examinee had been instructed to fast for 12 hours preceding the exam; at the exam, several tubes of blood were drawn one hour after the administration of an oral dose of 75 grams of glucose, which was given to stress-test for diabetic tendencies. The blood was allowed to clot, and then was centrifuged to separate the serum (liquid) portion from the blood cell portion.

A 2ml sample of the serum was taken and labeled, showing the sample's identification number, the donor's sex and date of birth, and date of blood sampling. The sample was frozen in screw-cap vials (under air). The following tests were routinely performed on the remaining blood serum: cholesterol, glucose, creatinine, calcium, total protein, albumin, uric acid and serum glutamic oxalacetic transaminase.

By the late 70's, storage of the uncataloged frozen samples that had been collected between 1964 and 1971 was becoming a serious problem at the KPMCP facilities. In 1980, at the suggestion of Henry Kaiser's widow, Mrs Alyce Kaiser (and with the encouragement of Drs Garfield and Collen, as well as that of Dr Gary D Friedman, the head of epidemiologic research at KPMCP), OFAS assumed custody of the collection, undertaking the systematic cataloging of this valuable, but at-the-time incipient, resource.

After validating the chemical integrity of the long-stored samples (see below), the collection was packed in dry-ice and moved by refrigerator truck from California to interim storage in a freezer warehouse in Brooklyn, NY. Over the next two years, OFAS computer-cataloged the collection, creating a Serum Treasury that -- with the medical data bank already managed by KPMCP -- came to be described by the World Health Organization as "among the most valuable resources currently available in biological banking."

Levels of DHEAS in the 517 long-frozen sera correlated extremely well with levels of DHEAS in the 2,500 unfrozen samples of the aforementioned OFAS study, and this excellent correlation established that the chemical integrity of the serum had been maintained over the 9 to 16 years of frozen storage. Subsequent studies using the Serum Treasury have repeatedly confirmed the persistent chemical integrity of the samples, and so the Serum Treasury has proved to be the uniquely valuable biomedical resource its conceptors envisioned in 1964.

In this system, a refrigerator truck transported a crate of samples to the OFAS laboratories where they were stored in a -40° chest freezer. The information on the tube's label was dictated onto audio tape; the tube was then placed in a specially designed, grid-numbered, partitioned box. The record included: birth date, date of blood sampling, sex, sample identification number, and the OFAS catalog numbers that identify the tube's precise location by box and grid-slot. All this information for each box was then verified by another technician who compared the audio tape with each tube's label; corrections were made as needed. The boxes of newly cataloged samples were then returned to the freezer warehouse, stacked in a systematic manner, and another crate picked up for cataloging. At no time were samples allowed to defrost.

To computerize the information from the tubes' labels, personnel listened to the audio tape on each 100-tube box and entered the information into a computer in accordance with a program customized by OFAS. The information, displayed on the screen, was verified by another technician against the original audio tape, and corrections were made as needed. A list was then printed for each box showing all the tubes' data, and the list was rechecked against the original audio tape. These files were moved on tape as 30-character records (per tube) in ASCII format to assure compatibility between the data entry computers and the OFAS principal computer. With a special program, the ASCII data were compressed to a 14-byte binary record for the OFAS Serum Treasury Master File.

A separate computerized index -- in order of ascending sample identification number -- is also maintained and routinely updated. It is used, for example, to determine the availability of serial samples from the same donor. (Anonymity is maintained through the identification of serum samples by numbers only.)

In the new, double-entry, self-checking program, the label information from 100 tubes is consecutively keyboarded directly into the computer. The same information from these tubes is directly entered again. The program emits a sound alerting the operator to any non-matching entries and prints a list of non-matches. Any mistakes are corrected by double-reentry of the tube label data after the 100-tube cross-check is complete. (The program will not print or end until all entries match.) When everything matches, a printout of all entries is made and filed, and the disk information is transferred to the Serum Treasury Master File which is automatically updated.

The catalog-storage system makes locating and retrieving a sample from the -40°C freezer a simple, five-minute job.

All refrozen samples are recataloged and stored together in new boxes in the Study Section of the freezer. The information for these tubes (box, grid-slot, etc, including the residual volume of serum) is maintained in a separate Study Serum Master File. Also, the general Master File is updated to show the new box and grid-slot locator numbers for these tested research samples.

The Serum Treasury's current home was constructed in 1986-1987 at the OFAS Biomedical Research Station in Cold Spring-on-Hudson, NY. This 5,400 cu ft freezer was built to exceed the specifications of the original storage facility at KPMCP.

In California, the collection was maintained at -30°C until June 1969, and at -25°C ± 2°C thereafter. It is unlikely that sample temperatures ever exceeded -23°C, except for a single short episode in December 1968 when a 22-hour power outage led to a rise in freezer air temperature to -15°C, and an estimated rise in sample temperature to -21°C.

Since arriving at OFAS, the original 263,000 samples (and all subsequent additions) have been kept at -40°C ± 2°C. A second, more energy-efficient freezer was constructed to house the Serum Treasury in 2001; it is capable of maintaining samples at -50°C.

Of the 199,500 samples added since January 1984, 13,185 are from previous donors to the original 1964-1971 Serum Treasury collection.