A dynamical measure of the black hole mass in a quasar 11 billion years ago

Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH)1-3. These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase4-6. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8-12 billion years ago (redshifts 1-3)7. Here we report a dynamical measurement of the mass of the black hole in a luminous quasar at a redshift of 2, with a look back in time of 11 billion years, by spatially resolving the broad-line region (BLR). We detect a 40-μas (0.31-pc) spatial offset between the red and blue photocentres of the Hα line that traces the velocity gradient of a rotating BLR. The flux and differential phase spectra are well reproduced by a thick, moderately inclined disk of gas clouds within the sphere of influence of a central black hole with a mass of 3.2 × 108 solar masses. Molecular gas data reveal a dynamical mass for the host galaxy of 6 × 1011 solar masses, which indicates an undermassive black hole accreting at a super-Eddington rate. This suggests a host galaxy that grew faster than the SMBH, indicating a delay between galaxy and black hole formation for some systems.

Test of the Einstein Equivalence Principle near the Galactic Center Supermassive Black Hole

During its orbit around the four million solar mass black hole Sagittarius A* the star S2 experiences significant changes in gravitational potential. We use this change of potential to test one part of the Einstein equivalence principle: the local position invariance (LPI). We study the dependency of different atomic transitions on the gravitational potential to give an upper limit on violations of the LPI. This is done by separately measuring the redshift from hydrogen and helium absorption lines in the stellar spectrum during its closest approach to the black hole. For this measurement we use radial velocity data from 2015 to 2018 and combine it with the gravitational potential at the position of S2, which is calculated from the precisely known orbit of S2 around the black hole. This results in a limit on a violation of the LPI of |β_{He}-β_{H}|=(2.4±5.1)×10^{-2}. The variation in potential that we probe with this measurement is six magnitudes larger than possible for measurements on Earth, and a factor of 10 larger than in experiments using white dwarfs. We are therefore testing the LPI in a regime where it has not been tested before.

State of the Art of Sentinel Node Biopsy in Oncology

Sentinel node biopsy has become a standard diagnostic procedure to assess lymph node status of various tumors. The combination of blue dye and a radioactive tracer offers the best chances of identifying the sentinel lymph node. Most progress in the technique of the sentinel node procedure has been made in melanoma and breast cancer. In melanoma, sentinel node biopsy has been introduced as a fundamental procedure for staging. Information on the lymphatic drainage from a melanoma can have a direct impact on the surgery. More recently, the technique has been successfully introduced in the management of breast cancer, in which a large number of unnecessary axillary dissections could be avoided. However, there are many other potential fields of application of the sentinel node biopsy (e.g. endometrial, vulvar, head and neck cancers) that are worthy of investigation. In any case, multicenter trials are required to standardize the procedures, taking into account several variables such as particle size and mode of delivery of the radiotracer, amount of radioactivity administered, number and location of injections, and choice of the hand-held probe. We briefly describe the technical and historical aspects of the sentinel node biopsy and summarize the main clinical trials proposed and/or performed in the field.

Sentinel Node Biopsy in Patients with Cutaneous Melanoma of the Head and Neck

Biopsy of head and neck sentinel nodes (SNs) can be technically problematic due to the unpredictable and variable drainage patterns of this anatomic region. The aim of the present study was to evaluate the feasibility of SN biopsy for cutaneous melanoma of the head and neck. We performed SN biopsy in 17 patients affected by stage I cutaneous melanoma of the head and neck on the basis of lymphoscintigraphy, blue dye and gamma probe. A total of 24 procedures were performed. Drainage to more than one lymphatic basin was observed in five patients (two basins in three cases and three basins in two cases) and in all cases SN biopsy was performed in all basins. The biopsy distribution by site was: six cervical nodes, five parotid nodes, four supraclavicular and submandibular nodes, three auricular and axillary nodes. The SN identification rate was 87.5% (21/24); metastases were discovered in four cases, with a positivity rate of 23.6%. At the time of writing, 1 patient is alive with local disease, 3 patients are dead and 13 are alive and free of disease with a follow-up ranging from 1 to 40 months (median, 21 months) following SN biopsy. In our opinion preoperative lymphoscintigraphy and the intraoperative use of a gamma probe are useful for the identification of lymphatic drainage of cutaneous melanoma of the head and neck.

Using scale characteristics and water temperature to reconstruct growth rates of juvenile steelhead Oncorhynchus mykiss

Juvenile steelhead Oncorhynchus mykiss from a northern California Central Valley population were reared in a controlled laboratory experiment. Significantly different rates of growth were observed among fish reared under two ration treatments and three temperature treatments (8, 14 and 20°C). Wider circulus spacing and faster deposition was associated with faster growth. For the same growth rate, however, circulus spacing was two-fold wider and deposited 36% less frequently in the cold compared to the hot temperature treatment. In a multiple linear regression, median circulus spacing and water temperature accounted for 68% of the variation in observed O. mykiss growth. These results corroborate previous research on scale characteristics and growth, while providing novel evidence that highlights the importance of water temperature in these relationships. Thus, this study establishes the utility of using scale analysis as a relatively non-invasive method for inferring growth in salmonids.

Growing experience with mTOR inhibitors in pediatric solid organ transplantation

Controlled trials of mTOR inhibitors in children following solid organ transplantation are scarce, although evidence from prospective single-arm studies is growing. Everolimus with reduced CNI therapy has been shown to be efficacious and safe in de novo pediatric kidney transplant patients in prospective trials. Prospective and retrospective data in children converted from CNI therapy to mTOR inhibition following kidney, liver, or heart transplantation suggest preservation of immunosuppressive efficacy. Good renal function has been maintained when mTOR inhibitors are used de novo in children following kidney transplantation or after conversion to mTOR inhibition with CNI minimization. mTOR inhibition with reduced CNI exposure is associated with a low risk for developing infection in children. Growth and development do not appear to be impaired during low-dose mTOR inhibition, but more studies are required. No firm conclusions can be drawn as to whether mTOR inhibitors should be discontinued in children requiring surgical intervention or whether mTOR inhibition delays progression of hepatic fibrosis after pediatric liver transplantation. In conclusion, current evidence suggests that use of mTOR inhibitors in children undergoing solid organ transplantation is efficacious and safe, but a number of issues remain unresolved and further studies are required.

[Physical aspects of different tomosynthesis systems]

Digital breast tomosynthesis (DBT) is a new image processing technique based on digital mammography technology. Image slices of the stationary compressed breast are reconstructed from multiple images taken at different angles of the X-ray tube at the same time. The main goal is to achieve a similar radiation dose exposure as common encountered in traditional digital mammography. One of the key advantages of DBT is that lesions are less likely to be hidden amongst normal tissues as they are in traditional digital mammography. This way the quality of diagnosis can be improved, especially for dense breasts. Current DBT implementations from several manufacturers differ in certain features such as scanning angle, number of projections, scanning time, pixel size, reconstruction methods and type of tube movement. A comparison and description of these different characteristics as well as a discussion on the proposed number of imaging planes and related radiation dose requirements are given.

THE PRODUCTION OF PERSISTENT ALOPECIA IN RABBITS BY ROENTGEN RADIATION; A STUDY OF THE MINIMUM DOSE REQUIRED AND THE CONSISTENCY OF THE REACTION

Seven areas on the abdomen of each of fourteen rabbits were exposed to soft Roentgen radiation of constant quality in doses varying, in the region of the value critical for the production of persistent alopecia, by regular steps of about 4 per cent. Without exception the critical dose was found to lie between two such values, the upper limit being represented by exposures on eight of the animals and the lower on ten of them. With certain reservations, the critical dose corresponds to the production of 2.04 x 10¹⁵ ions of either sign per gm. of tissue.

STUDIES ON X-RAY EFFECTS : VI. EFFECT OF THE CELLULAR REACTION INDUCED BY X-RAYS ON CANCER GRAFTS

Small areas of the skin in the groin of mice were subjected to an erythema dose of x-rays and a week later a cancer graft was inoculated intracutaneously into the area and at the same time a like graft was inoculated in the same manner in the opposite groin protected from x-rays. The graft in the x-rayed area showed a low percentage of takes, while that in the normal skin gave the usual high percentage When the graft was introduced into the subcutaneous tissues it grew equally as well in the x-rayed area as in the protected area. Histological examination shows the skin layers, a few days after x-ray treatment, to be markedly infiltrated with round cells of the lymphoid type. The reaction did not extend deeper than the skin layers. It is suggested that this local lymphoid reaction induced by the x-rays controls the graft made into the skin, while its absence in deeper tissues accounts for the growth of the grafts more deeply implanted.

SOME FACTORS DETERMINING THE LOCALIZATION OF A CHICKEN TUMOR AGENT

A localization out of the blood stream of the agent causing a chicken tumor, with the subsequent development of the growth can be brought about in the breast muscle, by inducing in this tissue a reaction by such substances as Scharlach R, tar, embryonic tissue and kieselguhr. Localization in the reaction tissue elicited by kieselguhr takes place relatively infrequently. The earlier stages of the reaction induced by these substances localize the tumor agent more regularly than the later stages of the reaction.

THE EFFECT OF A GROWTH-RETARDING FACTOR FROM NORMAL TISSUES ON SPONTANEOUS CANCER OF MICE

Extracts of desiccated homologous embryo skin and placenta decrease markedly the rate of postoperative local recurrence after the surgical removal of spontaneous cancer of mice. Autografts after a short period of contact with these extracts either failed to grow, or, in the majority of instances, their subsequent growth was definitely retarded. Intraperitoneal injection of the extracts was followed by cessation of growth of established tumors in more than two-thirds of the animals treated, and among these many of the tumors regressed and over 20 per cent were completely absorbed. Tumor mice treated with either extract rarely developed new malignant foci, though this happened frequently in untreated mice.

STUDIES ON X-RAY EFFECTS : IX. THE ACTION OF SERUM FROM X-RAYED ANIMALS ON LYMPHOID CELLS IN VITRO

Lymphoid cells, prepared from the thymus and lymph glands of rats, when suspended in the serum of x-rayed rats and incubated for 2 hours, increase in number from 15 to 30 per cent, and mitotic figures are found among these cells in fairly large numbers. A like suspension of cells in normal serum undergoes rapid disintegration and in only one instance among a large number of films examined was a mitotic figure found. The stimulative effect of the serum from x-rayed rats endures from 1 to 2 hours after the exposure but is not detectable in the serum taken 17 hours or later after the treatment. Serum x-rayed in vitro is devoid of stimulative action. The lymphoid cells of rabbits and guinea pigs are so fragile as to make impossible the obtaining of counts accurate enough for experimental purposes. The serum of one species caused such rapid disintegration of the cells of another that it was impossible to determine the specificity of the reaction.

PROPERTIES OF THE CAUSATIVE AGENT OF A CHICKEN TUMOR : VI. ACTION OF THE ASSOCIATED INHIBITOR ON MOUSE TUMORS

Water extracts of desiccates of certain relatively slow-growing strains of Chicken Tumors I and X, or the exudates from such tumors, definitely inhibited the growth of a mouse sarcoma (Crocker 180), and were without effect on a mouse carcinoma (Bashford 63) or Mouse Tumor S/37, a rapidly growing sarcoma derived from the stroma of a carcinoma. Extensive control tests with extracts from rapidly growing chicken tumors, and from tissues of normal and immune chickens showed no inhibiting action. There was no demonstrable action on the mouse tumors of sera from immunized rabbits, which neutralize the chicken tumor agent, nor of the sera from chickens highly immune to the chicken tumors.

PROPERTIES OF THE CAUSATIVE AGENT OF A CHICKEN TUMOR : II. THE INACTIVATION OF THE TUMOR-PRODUCING AGENT BY MONOCHROMATIC ULTRA-VIOLET LIGHT

Even though part of the energy of the incident light is probably absorbed by chemical entities which play no part in the specific reaction of inactivation, nevertheless the wave lengths most active in destroying biological cells or agents will presumably be found to be among those absorbed in the highest proportion. This would indicate that the curves here presented are approximately reciprocal to the coefficients of absorption of particular substances, the destruction of which caused the inactivation of the agents or the death of the cells. The similarity between the curves for bacteria, virus, and phage, both in shape and in total involved energies, suggests the presence of a common factor, or of closely related chemical entities, sensitive to ultra-violet light, whereas the data for the tumor agent suggest that its inactivation is due to the destruction of a substance having an essentially different spectral absorption, and therefore of a different chemical character. While the amount of ultra-violet energy required to affect the tumor agent is great, it is still less than that involved in the inactivation of some of the enzymes (7). A study is under way to compare the deduced spectral analysis with the actual coefficients of absorption of the highly purified tumor agent.

PROPERTIES OF THE CAUSATIVE AGENT OF A CHICKEN TUMOR : VIII. THE EFFECT OF TESTICLE EXTRACT ON THE RATE OF GROWTH OF CHICKEN TUMOR I

Extracts prepared from the testicle tissue of the rat, rabbit, fowl or bull, injected together with extracts of Chicken Tumor I or with cells of this tumor, showed no definite effect of either enhancement or inhibition as concerned the resulting tumors.

FURTHER OBSERVATIONS ON AN EXPERIMENTALLY PRODUCED SARCOMA OF THE CHICKEN

Numerous attempts have been made by us to separate from the cells of a tar sarcoma of the chicken (Chicken Tumor 9) a causative agent for the growth. Experiments with filtrates and desiccates injected as such or in combinations with embryonic tissues have all failed to give positive results. So too have injections of filtrates and desiccates into developing chick embryos failed to yield a response. The results confirm those of previous work with the tumor in this laboratory. The growth would appear to differ in a fundamental respect from all tumors of the fowl previously studied.

EFFECT OF SMALL DOSES OF X-RAYS ON HYPERTROPHIED TONSILS AND OTHER LYMPHOID STRUCTURES OF THE NASOPHARYNX

46 individuals with tonsils both hypertrophied and otherwise pathologically altered and some of whom had in addition adenoid masses and lymphoid deposits posterior to the pillars of the fauces, were given exposures to x-rays. In all but four cases the treatment was followed by marked atrophy of the tonsils and the other lymphoid deposits, attended by an opening and drainage of the tonsillar crypts. As this process progressed the previously enlarged tonsils assumed a smooth and normal appearance and the hemolytic bacteria-streptococci and staphylococci chiefly-which were often present in the affected tonsil disappeared usually within 4 weeks of the treatment.

PROPERTIES OF THE CAUSATIVE AGENT OF A CHICKEN TUMOR : VII. SEPARATION OF THE ASSOCIATED INHIBITOR FROM TUMOR EXTRACTS

The inhibiting factor present in certain relatively slow-growing strains of Chicken Tumor I and in Chicken Tumor X is adsorbed from extracts of the desiccated tumors by aluminum hydroxide (Willstätter Type C) and can be released in effective quantities from this combination by treatment with basic sodium phosphate.

EFFECT OF INDUCED CELLULAR REACTION ON THE FATE OF CANCER GRAFTS : IV. STUDIES ON LYMPHOID ACTIVITY

Mice sensitized by an injection of 0.2 cc. of rat blood and 10 days later inoculated with a mixture of rat blood and a transplantable mouse cancer showed a high degree of immunity to the cancer growth, while mice sensitized in the same manner and inoculated with cancer graft with no rat blood showed no immunity. Likewise, non-sensitized mice inoculated with a mixture of rat blood and cancer cells showed no immunity. Mice sensitized to rat blood and then given a series of doses of x-rays between the time of this injection and the inoculation of the cancer-rat blood mixture showed a suppression of the factors affording protection or immunity, since the cancers grew as well in these animals as in the controls. Mice were sensitized with rat blood and 10 days later inoculated with a cancer-rat blood mixture. 20 hours after the inoculation when the cellular exudation was at its height, the cells were destroyed by a local dose of x-rays. The degree of immunity was reduced and the cancers grew almost as well as in the controls.

A FACTOR FROM NORMAL TISSUES INHIBITING TUMOR GROWTH

Extracts of desiccated embryo skin and placenta have been found to exert a definite retarding action on the growth of two transplantable carcinomas of mice, but they were without effect on sarcomas. In tests involving some 828 inoculations of the tumor cells and the extracts, complete suppression of growth occurred in from 55 to 71 per cent of instances, as compared with 21 to 27 per cent in the controls, and where growth was not completely suppressed some retardation was found in practically every instance. To judge from findings in rabbits the inhibitor is not demonstrable in the placenta until the beginning of the second third of pregnancy, reaches its maximum by the last third, but disappears about 2 or 3 days before term. Extracts of fresh placenta are without effect, and no very definite inhibition was noted in extracts of a variety of other desiccated or fresh tissues. The conclusions here reported are based on the results of over 3800 inoculations.

PRIMARY LUNG TUMORS IN MICE FOLLOWING THE CUTANEOUS APPLICATION OF COAL TAR

The external application of tar to a number of separated areas on the surface of mice, in such fashion that no single area is irritated sufficiently long to cause lesions of the skin, has resulted in a very high incidence of lung tumors. This incidence ranged from 60.0 per cent in one experiment to 78.3 per cent in another. Control mice from the same stock but from 3 to 6 months older, and for that reason the more liable to spontaneous lung tumors, failed to show a single instance of such growths. Even in a stock in which spontaneous lung tumors had been frequent, the incidence for corresponding age periods has never been above 5.5 per cent while the average has been between 1 and 2 per cent over a period of years. The tumors in the tar-painted animals occur as small white nodules, either single or multiple. They are typical epithelial neoplasms, identical histologically with those described by previous authors as occurring spontaneously in mice. Some possible factors in the causation of the tumors are briefly discussed.

STUDIES ON LYMPHOID ACTIVITY : V. RELATION BETWEEN THE TIME AND EXTENT OF LYMPHOID STIMULATION INDUCED BY PHYSICAL AGENTS AND THE DEGREE OF RESISTANCE TO CANCER IN MICE

It has been shown that resistance to transplanted cancer follows stimulation of the lymphoid tissue when the stimulation is induced by either heat or small doses of x-rays. In this paper we have attempted to determine whether the degree of immunity had a quantitative relation to the amount of the stimulation. Fortunately, the two methods at our disposal give stimulation of markedly different characters. The small dose of x-rays gives a sluggish lymphoid cell reaction of short duration with a definite latent period between the treatment and the evidence of marked stimulation, while after heat a short period of depression is followed by a sharp stimulation continuing over a much longer period. The cancer inoculation into groups of mice made immediately after exposure to x-rays shows little resistance, while the inoculation made at the height of the stimulation phase shows a definite increase in the immunity. Animals inoculated with cancer immediately after the heat treatment exhibit a pronounced immunity, but not so marked as that shown when the inoculation is made at the height of the stimulation. The amount of resistance shown when the cancer inoculation is made at the height of the moderately stimulating effect following exposure to x-rays, is much less than that seen when the inoculation is made at the height of the heat effect when the degree of stimulation is much greater. When the lymphocytosis sets in after the tumor graft is established only a slight effect is noted. All these results together are taken to indicate that the degree of immunity is dependent on the amount of lymphoid stimulation existing either at the time of or following soon after the cancer inoculation.

LOCAL RESISTANCE TO SPONTANEOUS MOUSE CANCER INDUCED BY X-RAYS

Autografts from spontaneous cancers of mice when replanted into areas previously exposed to an erythema dose of x-rays, failed to grow in the majority of instances (71.4 per cent), while similar grafts inoculated into untreated areas grew in a large proportion of the animals (83.6 per cent). Autografts of spontaneous cancer, established and growing in the skin, disappeared in 76 per cent of animals after the tumor and surrounding tissues had been exposed to an erythema dose of x-rays, whereas other autografts of similar derivation that had been given a like dose of x-rays outside of the body and had been implanted in the same animals grew progressively in 96 per cent of instances. That this result was not due to a greater susceptibility of the cancer cells x-rayed in situ was shown by the fact that tumors treated in situ with x-rays and then replanted in an unrayed location on the same animal grew actively. Evidently the ray had done no direct damage to the cancer cells.

PROPERTIES OF THE CAUSATIVE AGENT OF A CHICKEN TUMOR : IV. ASSOCIATION OF AN INHIBITOR WITH THE ACTIVE PRINCIPLE

The presence of an inhibiting substance in the chicken tumor is shown by the fact that a desiccate of the tumor is more active after it has been washed two or three times with water, and that an extract of the tumor is more potent after some factor is removed by adsorption on aluminum hydroxide. When the tumor-producing factor in an extract of a slow-growing tumor has been destroyed by heating at 55 degrees C. it is found to have the property of neutralizing a highly active tumor extract. This inhibiting property is destroyed by heating over 65 degrees C.

EFFECT OF DRY HEAT ON THE BLOOD COUNT IN ANIMALS : III. STUDIES ON LYMPHOID ACTIVITY

Animals subjected to dry heat for a short period show a sharp fall in the total white blood count, both the polymorphonuclear leucocytes and the lymphocytes taking part in the fall. Following this there is a slow recovery on the part of the polymorphonuclear leucocytes, which generally require several weeks to regain their normal number. The lymphocytes rise rapidly after the initial fall and continue to rise for 2 or 3 weeks. This increase often amounts to a gain of over 200 to 300 per cent above the normal count for the animal. The observations were made on mice, rats, and guinea pigs. The circulating lymphocytes during the more active stage of stimulation after heating show numerous examples of amitotic division.

A COMPARISON OF THE EFFECTS OF X-RAY AND DRY HEAT ON ANTIBODY FORMATION

Rabbits x-rayed in doses sufficient to reduce the amount of their lymphoid tissue without damage to the bone marrow showed a definite deficiency in the production of precipitins, bacterial agglutinins, and protective antibodies. On the other hand, rabbits subjected to exposures of dry heat sufficient to increase the activity of the lymphoid organs, on immunization develop antibodies in larger quantity than do untreated animals immunized by the same process.

PROPERTIES OF THE CAUSATIVE AGENT OF A CHICKEN TUMOR : III. ATTEMPTS AT ISOLATION OF THE ACTIVE PRINCIPLE

By two methods a protein fraction can be separated out from a Chicken Tumor I extract, which carries all the tumor-producing agent. The precipitate can be dissolved and reprecipitated a number of times without loss of activity. The agent can be largely dissociated from the protein as shown by the fact that aluminum hydroxide will adsorb the protein from an extract and leave the agent behind. This purified material has a very low protein content, if any, as shown by both chemical and biological tests.

CONDITIONS DETERMINING THE TRANSPLANTABILITY OF TISSUES IN THE BRAIN

In confirmation of Shirai's observation, we find that transplantable mouse tumors grow actively when inoculated into the brains of rats, guinea pigs, and pigeons, whereas subcutaneous or intramuscular grafts in the same animals fail. This growth of foreign tissue in the brain, however, takes place only when the grafted material lies entirely in the brain tissue; if it comes in contact with the ventricle a cellular reaction takes place with resultant destruction of the graft. The growth of foreign tissue in the brain may be completely inhibited by simultaneous inoculations of a small bit of autologous but not by a bit of homologous spleen tissue. Mice highly immune to subcutaneous transplants of mouse cancer show no resistance to such tumors when the inoculation is made into the brain. Although the brain is without obvious power of resistance to implants of transplantable heteroplastic mouse tumors, yet grafts of spontaneous tumors fail to grow there even, as a rule, when tumor implanted and animal host are of the same species.

THE LYMPHOCYTES IN NATURAL AND INDUCED RESISTANCE TO TRANSPLANTED CANCER : IV. EFFECT OF DRY HEAT ON RESISTANCE TO TRANSPLANTED CANCER IN MICE

The marked and durable stimulation of the lymphoid elements induced by dry heat applied to the animal results in the establishment of a high degree of immunity to certain transplantable cancers in mice. This immunity is evident when the tumor used gives a low, as well as when it gives a high percentage of takes.

EFFECT OF PREPUBERTY CASTRATION ON SUBSEQUENT CANCER IMPLANTATION

Male and female mice castrated during the first 7 weeks of life and implanted with cancer at later periods show a resistance definitely higher than do intact animals of the same age. This increased refractiveness is evident at 3 months after the operation but is more pronounced at 8 months to a year. Even castration in early adult life seems to increase the refractory state to later cancer inoculation. On the other hand, adult mice inoculated within a week after castration show slight if any evidence of increased resistance.

PROPERTIES OF THE CAUSATIVE AGENT OF A CHICKEN TUMOR : V. ANTIGENIC PROPERTIES OF THE CHICKEN TUMOR I

The injection of tumor extracts and their active protein fractions into rabbits induced the formation of precipitins and neutralizing antibodies. When the major portion of proteins in the tumor extract had been eliminated it induced the formation of neutralizing antibodies, but not of precipitins. The tumor agent, more highly purified by removal of the viscous fraction, did not induce precipitins, and only 2 out of the 15 sera gave any evidence of neutralizing bodies. After the removal of the major portion of protein, the extracts showed insufficient interaction with the sera to fix complement.

[Two sisters with progressive familial intrahepatic cholestasis]

A few months after birth two sisters aged 5 and 9 years had developed cholestasis and abnormal liver functions with symptoms including itching and jaundice. The younger sister also developed rickets and clotting disorders. On clinical, biochemical and immunohistopathological grounds the diagnosis of 'progressive familial intrahepatic cholestasis (PFIC) type 2' was made. Medical treatment was not succesfull in reducing symptoms. An ileocolonic bypass in the younger child was not effective. Subsequently, both patients underwent partial external biliary diversion (PEBD). Except for a period of intermittent itching in the younger child, both patients remained free of symptoms 2 years after PEBD. In cases where an early diagnosis is made, PEBD could delay or even prevent the necessity of liver transplantation.