« 上一頁繼續 »
TESTIMONY TO SUBCOMMITTEE ON CONSTITUTIONAL AMENDMENTS OF U.S. SENATE
JUDICIARY COMMITTEE Mr. Chairman and Members: My name is Jerome Lejeune. I am a doctor of medicine, taking care of disabled children at the Hopital des Enfants Malades (Sick Children's Hospital). I have spent ten years in full-time scientific research, and am now Professor of Fundamental Genetics at the Universite Rene Descartes in Paris. Having always been a human geneticist, I try to remain human in dealing with genetics,
After working specifically with mongoloid children, I demonstrated that this disease was due to an extra chromosome. For this work, I had the great honor of receiving the Kennedy award from the late President.
Specializing in the study of the human chromosomes, I have frequently visited the United States, and had the honor in 1970 of receiving the William Allen Memorial Medal in San Francisco from the American Society of Human Genetics.
With my colleagues in Paris, we have particularly described many different chromosomal conditions in man, and also compared the chromosomes of man and of primates like the great apes.
We are deeply involved in new techniques of analysis, and have achieved specific recognition of the old and the new chromosomes during cell divisions.
We are also working on the effect of super-numerary chromosomes. In mongoloid children, we have recently demonstrated an excess of a specific enzyme, super oxyde dismutase. The eventual relationship between this trouble and the mental retardation of the affected child is under investigation.
The transmission of life is quite paradoxical. We know with certainty that the link which relates parents to children is at every moment a material link, for we know it is from the encounter of the female cell (the ovum) and the male cell (the spermatozoa), that a new individual will emerge. But we know with the same degree of certitude that no molecule, no individual particle of matter enclosed in the fertilized egg, has the slightest chance of being transmitted to the next generation. Hence, what is really transmitted is not the matter as such, but a specified conformation of the matter, or more precisely, an "information”.
Without receiving the complex machinery of coded molecules like DNA, RNA, proteins, and so on, which are the vehicle of heredity, we can see that this paradox is common to all the processes of reproduction, whether natural or man-made. For example, a statue must be built out of some material, and could not exist if made of pure void. During the casting process, there exists at every moment a contiguity of molecules between the statue and the cast, and later, between the cast and the replica. But, obviously, no matter is reproduced, for the replica could be plaster, or bronze, or anything else. What is indeed reproduced is not the matter of the statue, but the form imprinted in the matter by the genius of the sculptor.
Indeed, the reproduction of living beings is infinitely more delicate than the reproduction of an inanimate form, but the process follows a very similar path, as we will see by another familiar example. On the magnetic tape of a tape recorder, it is possible to inscribe by minute alterations of local magnetism, a series of signals corresponding, for example, to the execution of a symphony. Such a tape, if introduced in the appropriate machine, will play the symphony, although there are no musicians in the machine and even no notes written on the tape. That's the way existence is played!
But, in this analogy, the magnetic tape is incredibly thin, for it is reduced to the size of a DNA molecule, the miniaturization of which is bewildering. To give an idea of this minuteness, we should remember that in this thread every character of each of us is exactly described. Thou shalt have blond hair, hazel eyes; thou shalt be six feet tall, and thou shall live some eighty years, if no road accidents intervene! All these instructions giving a full description of a man, are written in a thread one yard long. But the thread is so thin and so carefully packed inside the nucleus of the cell, that it would stay at ease on the point of a needle.
To give another impression, if we were to reassemble on this table all these threads which will specify each and every quality of the next three thousand million men who will replace us on the surface of this planet, this quantity of matter would fit nicely in an aspirin tablet. The fertilized egg is comparable to a tape recorder loaded. As soon as the mechanism is triggered, the human work is lived, instrict conformity to its program.
The very fact that we have to develop ourselves during nine months inside the bodily protection of our mother does not change anything, as you can easily observe by looking at the egg of the hen, from which the chilcken will emerge. It makes no difference whether he was incubated by the fowl, or by an electrical heating device! The chicken is still a chicken. If one day a child can be entirely grown in a test tube, the test tube will never believe that the child is its property !
Such a reduction of the human being to its very nature may not be very palatable, or intuitively satisfactory, but it accurately reflects the present state of our scientific knowledge. When a new student hears for the first time a symphony, let us say the Little Night Music by Mozart, he must listen to the whole in order to know it. But if he is a music lover, he will recognize Mozart at the first bars, and could tell the title at the second or third bar. It's the same with the human symphony. The specialist can recognize it at its first accents, even if a great number of various movements are required so that its general form becomes evident to everyone.
The infinitesimal threads of the genetic information are carefully coiled in little rods, the chromosomes, easily visible with an ordinary microscope. They are something like the magnetic tape inside the cartridge of a minicassette. Some twenty years ago, nobody could have told the cell of a man from the cell of a chimpanzee. Ten years ago, a simple counting of the chromosomes would have given the answer, 46 if a chimp. Since last year, if a student looking at a dividing fertilized egg or at the dividing cell of a blastocyst, could not tell them apart saying, “This one is a chimpanzee being, this one is a human being," he would fail the examination for his license.
But can we say that the early human being is an individual just after fe cundation. Does he have the two qualities of an individual: its unity and its uniqueness? Exceptions to unity are known: maybe once in every million births, some subjects carry, side by side, male cells (recognized by their X and Y chromosomes) and female cells (recognized by their two X chromosomes). Thus, these subjects are simultaneously provided with the masculine attributes of Hermes and those feminine of Aphrodite, hence the name hermaphroditism. One would belive that two fertilized eggs, one bound to be a boy, and the other bound to be a girl, have united together intimately, and it is quite the case. In the hermaphrodite, the mistake is extremely precocious, and seems to happen at the second division of maturation of the egg. Two reciprocal cells are produced, the ovum and its polar body, which would be here just as voluminous as the ovum. Both of them are simultaneously fertilized, each one by a different spermatozoa. Hence, exceptions to unity can happen very rarely at the time of fecundation.
Exception to uniqueness is more common : The identical twins, coming from the same fertilized egg, share exactly the same genetic patrimony, but each of them is obviously an individual by itself. From embryological knowledge, it seems impossible to separate one nature into two (or more) persons after the neural crest; that is, the first appearance of the nervous system, has differentiated. Hence, after the 13th day, no twins could occur. But, by inference, for the experimentation is not at hand at this time, it seems that the splitting must be extremely precocious, probably at the moment of the division of the first few cells of the embryo; that is, at the first encounter of the paternal and maternal sets of chromosomes.
These remarks on the exceptions of the individual "one and unique" corroborate the notion that every man begins at his very beginning. These theoretical and experimental notions can sometimes be directly felt by the persons themselves in exceptional situations. A very rate accident can occur at the moment the identical twins are formed. From an XY fertilized egg, bound to be a boy, two cells are produced : one XY will continue its masculine destiny, the other having received only the X chromosome (the Y being lost during the separation process) will develop itself as an imperfect girl. Two X chromosomes are required for a complete and harmonious femininity. Hence, the identical twins will be different: one normal boy and one frail and sterile girl.
In the first case we observed of such a young girl, she was some 18 years old and complained of a strange trouble. She feared to look at herself in a mirror because she pretended she was seeing her brother. Such an impression, far from anomalous, was an extraordinary intuition, very feminine indeed, of a very complex situation entirely undetected at that time. At the exception of
the lost Y chromosome, she was effectively a piece of her brother from whom she was issued.
These facts of human genetics can appear a little too theoretical, and the question must be asked whether common sense can recognize as such a tiny human being. If very early, only the scientist aided by refined techniques, can tell. If, let us say, at two months everybody knows, and has known for thousands of years.
At two months of age, the human being is less than one thumbs length from the head to the rump. He would fit neatly into a nutshell, but everything is therehands, feet, head, organs, brain-all are in place. If you look very closely, you would see the palm creases, and if you were a fortune teller, you could read the good adventure of that person. Looking still closer with a microscope, you could detect the finger prints like Sherlock Holmes-every document is available to give him his national identity card !
The incredible Tom Thumb really does exist. Not the one of the fairy tale, but the one each of us has been. For it is from this true story that the fairy tales were invented. If Tom Thumb's adventures have always enchanted the children, if they can still evoke emotion in grown-ups, it is because all the children of the world, all the grown-ups they have turned into, were one day a Tom Thumb in their mother's womb.
But can we scientists accept these fairy tales? The truth is indeed that Nature itself does. For instance, abortion is a normal process in imperfect mammals called marsupials. They have a special pouch n othe abdomen, conveniently accommodated to nurture the little. In the giant kangaroo, the abortion occurs at the same stage as the little Tom Thumb in man, and is roughly the same size. The aborted fetus then climbs into the fur of its mother to reach the pouch. The bewildering fact is that the kangaroo mother will let him do so, although she would not allow any other kind of animal drop in! If the poor brain of a female kangaroo can recognize the tiny creature as a kangaroo being, there is no wonder that geneticists can safely assure you that Tom Thumb is indeed a true human being.
From molecular genetics to comparative reproduction, nature has taught us that from its very beginning the "thing" we started with is a member of our kin. Being its own, human by its nature, never a tumor, never an amoeba, fish or quadruped, it is the same human being from fecundation to death. He will develop himself if the surrounding world is not too hostile. And the sole role of medicine is to protect the individual from accidents as much as possible during the long and dangerous road of life.
Senator Bayh. Thank you, Dr. Lejeune. (General applause.]
Senator Bays. For the sake of those of you who have not been here before, I will repeat what I said previously. We have some very intricate matters to discuss. They are, indeed, matters of life and death. They should not be and are not going to be decided by an applause meter. What we have found historically in committee hearings, inasmuch as both sides of this issue are represented, as they should be, by witnesses and by members of the audience, that insisted of directing our attention at what is being said here and trying to stimulate our intellect, each position on this issue tries to compete with one another to see who can command the longest and loudest amount of applause.
I hope that that observation will be accepted by those who are here, and it will not be necessary to repeat to you that I do not think applause helps us in our process of deliberation.
Dr. Lejeune, we appreciate your testimony.
May I ask that we get Dr. Liley's, and then we can have a discussion back and forth between you gentlemen and responses to questions from my colleagues and myself.
57-676 0 - 76 - 15
STATEMENT OF DR. ALBERT W. LILEY, KCMG, POST GRADUATE
SCHOOL OF OBSTETRICS AND GYNECOLOGY, UNIVERSITY OF
Mr. Chairman and members, my name is Albert William Liley. I hold qualifications and have been trained in neurophysiology, obstetrics, and neonatal pediatrics. I hold the appointment of research professor in perinatal physiology at the Postgraduate School of Obstetrics and Gynecology in Auckland.
Like Dr. Lejeune, I also owe a debt to the United States of America, having spent a year of sabbatical leave in the United States on an international post doctoral fellowship of the U.S. Public Health Service and at the expense of the American taxpayer.
For 17 years, I have been engaged in work which would be most accurately described as fetal pediatrics. In 1963, I developed a technique by which babies, particularly Rh babies, who were beyond the aid of conventional thrapy, could be transfused in the uterus to tide them over to a deliverable maturity. And in this situation, it is apparent that the fetus may be ill, can receive diagnosis and treatment, just like any other patient.
I regard it as a bitter irony that just when, for the first time, the fetus arrives on the medical scene who can be a patient, ill, receive diagnosis and treatment, just like any other patient, there should be such strenuous efforts to make him a social nonentity. And I would find it as a physician extraordinarily arbitrary if I were required to regard some fetuses as patients and to treat them properly and to deny existence to others.
The diagnosis and treatment of fetal illness constitutes, of course, an invasion of fetal privacy, but it has presented to us both the opportunity and the techniques to observe the fetus in utero. These observations, initially obtained by techniques with which most people are not particularly familiar—for instance, ultrasound, electrical recording, X-rays and so on. But this does not for a moment deny the reality any more than, for instance, the fact that one of us here today might have tuberculosis or cancer would be any less real for the fact that it required a microscope or X-ray to diagnose it.
The techniques we developed for diagnosis and treatment of one particular illness in the fetus have now been extended to other diseases, to sorting out an assortment of problems in fetal and pregnancy physiology, as I have mentioned have allowed us to build up a picture of fetal environment and fetal behavior. I must concede immediately that the majority of observations have been made after about 16 weeks of gestation.
This has been forced upon us by two considerations. First, this has been the range in which our present state of knowledge or ignorance of fetal medicine has meant that we have been able to offer something to the fetus in the way of active treatment of illness. And it has also been forced upon us by limtiations of current techniques of investigation, for instance X-ray.
Now, however, we do have at our command other diagnostic techniques, for instance ultrasound, which are applicable before X-ray is suitable. And also, we have been able to observe fetuses. There are classic studies in the United States, for instance, by Davenport Hooker on the short life of the miscarried baby. And it is apparent that the observations we have made in mid-pregnancy and late pregnancy are but part of a spectrum which starts earlier in pregnancy. Where appropriate, I will refer to what we know of earlier fetal life.
On the physiological side, the picture that emerges is very different from the traditional idea that the fetus in utero is a placid, dependent, fragile, nerveless vegetable. There is no doubt whatsoever that in physiological terms the fetus is in command of the pregnancy. It is the fetus who is responsible for the endocrine or hormonal success of pregnancy. It is the fetus who solves the homograft problem.
In any outbreed population, such as the human population, mother and her fetus are inevitably immunological foreigners who could not exchange skin grafts, who could not be safely given a blood transfusion one from the other. Yet for the whole of pregnancy, they inust tolerate each in a par abiosis rather than a parasitic state, and it is the fetus who is responsible for this solution of this homograft problem, which I could point out in terms of surgical transplantation of organs is one of the major challenges to surgical physiologists.
It should be a satisfaction to all of us, Mr. Chairman, that we individually solved this problem ourselves before we were born, or we would not be here now.
The fetus is also responsible for the initiation of labor. In other words, the onset of labor is a unilateral decision by the fetus, that we each chose our own birthdays, unless our mother's doctor with good cause thought he had better reason than we did to know when we should be born. I could say, in an idiom perhaps more familiar to Americans, that the onset of labor is a unilteral declaration of independence of the fetus.
But independence, of course, immediately raises the question of whether fetal life is dependent, whether it is self-sustaining, or is only a partial existence because it is not truly independent. Of course, all the state of the fetal world demonstrates is that it is life in one particular physiological state of circumstances, just as with adults the physiological environment in which we can live is ridiculously circumscribed. We think that humans have conquered the poles and space and so on; in fact, all they have developed is the technology to take a small parcel of their own environment, their own life support system with them. So also the fetus has his own life-support system before birth, his membranes and placenta which, when he no longer needs them, at birth, in a different physiological environment, they are discarded.
The picture we have built up of fetal behavior also differs very much from the traditional picture of a dark and silent world, with perhaps some aimless kicking that begins about the 16th or 20th week of pregnancy. This movement in itself is interesting. It is known in English and American, also, I think, Mr. Chairman, as "quickening," coming from the old Anglo-Saxon "quick,” meaning alive or living.
But, in point of fact, this quickening is only a perception of movements by the mother rather than the beginning of fetal movement. The fetus has been moving ever since he had muscles and arms and