Experimental Biology and Medicine

A new closed-circuit apparatus has been described which continuously records oxygen consumption over periods of several days with automatic correction for changes in barometric pressure. The equipment is sensitive to less than 0.01 ml of oxygen per hour and can measure oxygen consumption over a wide range.

Phage infection of staphylococcal cells results in the formation and release of a lytic enzyme which causes the lysis of killed cells, and in conjunction with virus material, lyses living cells. This enzyme appears to be closely related to the autolytic system of uninfected cells, but is different in its pH optimum and activity for M. lysodeikticus. It increases during the latent period of phage infection, and we suggest it functions in the ultimate lysis and release of virus from the host cell.

1. The lipides partition and phospholipides turnover in plasma, liver, and aorta of intact rabbits was determined 6 hours after the subcutaneous injection of 1 mg/kg epinephrine in oil. 2. Significant changes were found in certain lipide fractions of liver and plasma but no alterations in the concentrations of the various aortic lipide fractions. 3. Specific activities of the plasma, liver and aortic phospholipides were significantly elevated in the rabbits given epinephrine; a particularly large change was found in the rate of aortic phospholipides formation. The possible relationship of the latter finding to the development of arteriosclerosis was discussed.

1. Studies are reported on the effect of 3 different anticoagulant systems on the rate and degree of optical clearing of lip-emic plasma by heparin clearing factor plasma. 2. Calcium binding anticoagulants decreased lipemia clearing proportional to the binding. 3. Protein binding anticoagulants also retarded or abolished clearing. 4. Chy-lomicra suspended in normal plasma cleared at a faster rate than those suspended in physiological salt solution. The addition of Ca or albumin enhanced the rate of clearing in physiological salt solution and the addition of both Ca and albumin resulted in almost complete restoration of clearing activity.

(1) One-stage prothrombin determinations in human plasma are only slightly affected by a wide range of GSH concentrations whereas relatively low levels of GSSG result in a marked lengthening of the prothrombin times. (2) Incubation of human plasma with either GSH or GSSG prior to initiation of prothrombin activation produces inhibitions of thrombin formation, the same degree of inhibition being observed with considerably lower concentrations of GSSG than of GSH. (3) A study of the precise point of action of the two forms of glutathione reveals that at least 75% of their over-all effects are due to reactions with clotting factors occurring during the pre-incubation period. (4) Pre-incubation of human plasma has resulted in an immediate decrease in the non-protein sulfhydryl concentration of the mixture over and above that accountable for by reaction with prothrombin. A concomitant increase in the non-protein disulfide level of the system appears to indicate the formation of some GSSG and supports the view that GSH inhibits clotting not only by reducing prothrombin disulfide linkages, but also by giving rise to some GSSG which, as has been shown subsequently, has marked inhibitory powers of its own. (5) Data have been presented which support the hypothesis that GSSG as well as other SH-oxidizing and -blocking agents react with at least one prothrombin conversion accelerator which is present in higher concentrations in dog plasma than in human plasma. This, in turn, implies the essential nature of free SH groups on such an accelerator and establishes their importance in the blood clotting mechanism.(6) Possible explanations and implications of these findings have been discussed.

Rats develop a metabolic lesion of the liver (respiratory decline in the Warburg) and subsequent dietary necrotic liver degeneration when fed a vit. E-free ration containing 30% Torula yeast as the sole source of protein. Depressed liver CoA values are observed in such animals. It is shown that CoA is not elevated by feeding of protective amounts of vit. E or Factor 3. Cystine, methionine, and cysteine, on the other hand, which promote growth under these conditions, raise the liver CoA values to near-normal levels. This action is not correlated to the varying degree of protection against liver necrosis and against the prenecrotic respiratory decline afforded by the individual S-amino acids. Hence, there is no apparent etiological relationship between concentration of CoA in the liver and the development of dietary necrotic liver degeneration.

Specific immune serum will protect the 48-hour chick embryo from the teratogenic and lethal effects produced by in fection with influenza-A virus. Inasmuch as antiserum can neutralize these effects completely in vitro and to a lesser extent in ovo this study provides serological evidence to implicate the virus as the cause of the syndrome described.

1. Chnages in capillary ressistance resulting from 8 forms of stress were studied on dogs, guinea pigs and rabbits in order to integrate previous similar studies on the human being and the rat. 2. Immediate and late responses were investigated and essentially the same patterns of response found as previously described. A comparison of the results obtained on all five species studied shows that practically every pattern may occur in each of the 5 species, yet in each species certain patterns predominate. Thus, the species difference resolves itself into a difference in the incidence in which the various patterns occur. 3. Knowledge of the capillary stress response is indispensable in any clinical or experimental study in which capillary resistance is measured. 4. An evaluation of the five species is given as to their suitableness to and relative value in capillary resistance studies.

It is concluded that acute permanent unilateral complete carotid (common, internal and external) or bilateral common carotid occlusions are well tolerated by monkeys. However, bilateral acute permanent complete carotid (common, internal and external) occlusions are only occasionally well tolerated. Bilateral complete carotid occlusions are more likely to be well tolerated if right and left sides are ligated separatel with a prolonged interval (over 6 weeks) between the 2-sided occlusions to permit establishment of adequate collateral circulation.

The reported experiments have demonstrated that: (1) various strains of vaccinia virus after intracerebral injection regularly produced tonic convulsions in mice; (2) at least one of these strains (NYBH) multiplied extensively in the brains of the mice; (3) mice were protected from the tonic convulsions and death caused by intracerebral injections of vaccinia virus, if they had recived a prior injection of either heated influenza virus or heated vaccinia virus.

The addition of 0.5% ethionine to the diet for 63 days caused the production of hepatic nodules resembling tumors in 16 out of 23 male albino rats. When ethionine was fed for 28 days and then removed for the remainder of the 63-day period, hepatic nodules were also produced in approximately the same proportion of cases (5 out of 8). No such nodules were observed in animals sacrificed after 28 days of ethionine administration.

As the centrifugal field increases the size of fruit fly larvae becomes limited and the growth rate decreases. A possible explanation is suggested for the apparently linear decrease of growth rate with field.

A study has been made of the binding of calcium and magnesium to serum albumin when both are present at the same time. It is shown that the ratio of the concentrations of bound calcium and bound magnesium is equal to the ratio of the concentrations of the ionized calcium and ionized magnesium.

A method is described whereby stable strains of cultured cells may be preserved at 4°C for periods in excess of 6 weeks. If sufficient time is allowed for recovery of cultures the process may be repeated many times. Essentials of the method are that the cells be in good condition when refrigerated and that no replacement in the nutrient fluid be made during the storage period and for several days after the cells are returned to 37°C.

1. The concentration of free amino acids and related compounds in muscle extracts from normal and from vit. E-dencient (dystrophic) rabbits has been determined by ion-exchange chromatography. 2. In the severely dystrophic animal, the levels of most of the amino acids were elevated. 3. 1-Methylhistidine, carnosine, and anserine were decreased in concentration. 4. The concentration of glycine was markedly reduced, even at the earliest stage of the disease.

Strains of mumps virus, which had been isolated in the chick embryo and maintained by up to 6 serial amniotic passages, were readily passed in series in cultures of human cancer cells (strain HeLa) and of monkey kidney epithelium. The lesions observed were dominantly cytolytic in nature. Primary isolations of mumps virus from the saliva of patients with acute parotitis have been achieved in both types of cultures with an efficiency and speed not matched by the chick embryo technic.

The optimal temperature for lysis using human C‘ is from 30°-32°C. As the temperature decreases from 37°C to 22°C the kinetic curve approaches the sigmoid shape typical of guinea pig C‘.

A factor sensitizing bacteria for phagocytosis is produced by dog blood cells. Sensitization results from direct contact of B. suis with dog but not guinea pig blood cells, or with a product of dog blood leucocytes diffusing into the suspension medium. The sensitizer differs from opsonin in that it is liberated from blood cells washed free of opsonin, from blood cells of animals free of specific opsonins, and is not fixed to sensitized bacteria. The sensitizer requires plasma but not opsonin for its action. It is not found in lysed washed dog or guinea pig blood cells, but is produced in demonstrable quantity by gentle agitation of dog leucocytes for 30 minutes at 37°C; it is not produced by dog red blood cells or guinea pig red or white blood ceils.

An in vitro method is described for demonstrating the binding by rat organ homogenates of I¹³¹ labeled antibodies produced by rabbits immunized with particular rat organs. By this test anti-kidney antibodies show specificity for kidney compared with other rat tissues, and anti-Walker rat carcinoma 256 antibodies specificity for this tumor tissue. These data are compared with I¹³¹ distributions found after injection of these antibodies by various routes into living rats. The results suggest that nearly all of these antibody molecules are also general anti-rat antibodies in that they are bound by components of other rat tissues. Such factors as relative circulation rates, blood vessel permeability to proteins, and intracellular or extracellular location of antigens, as well as relative organ specificity of antibodies as demonstrated by in vitro experiments, are probably therefore important in determining the localization of such antibodies in animal injection experiments.

Repeated administration of cortisone acetate in doses ranging from 4 to 3000 μg, injected during 10 days into mice bearing a transplantable mammary adenocarcinoma, inhibited the spontaneous production of lung metastases.

5'-Hydroxysulfapyridine, a urinary excretion product of sulfapyridine is as active in vitro as sulfapyridine against S. pyogenes and E. coli. It is without significant protective power in mice infected with these organisms. It is suggested that the loss of activity in vivo may be attributed to conjugation and excessively rapid elimination. Similar results were observed with the 3' and 6' isomers.

The rate of oxidation of alcohol has been studied in the mouse by determination of the rate of decline of the concentration of alcohol in the blood as well as by determination of the alcohol content of the whole animal at various times after administration of the drug. When observations are begun one hour after administration of alcohol, the rate of oxidation is constant and independent of the amount present. However, the rate of oxidation may be twice as great in the first hour as in subsequent hours. The effect is dependent on dose and to some extent on mode of administration.

Normal and irradiated rabbits were inoculated intravenously with approximately 10⁶ Klebsiella pneumoniae, Type A. At intervals thereafter plate counts were made on peripheral blood. During the first 4 hours after inoculation the rate of clearance of microorganisms from the blood stream was as rapid and almost as complete in rabbits which had been exposed 1-8 days before with 800 r total body x-irradiation (LD_50/30) as in unirradiated controls. From the 8th hour on, in most of the rabbits 3-8 days post-irradiation, the colony counts increased steadily until the animals died. These findings indicate that in the irradiated rabbit the reticulo-endo-thelial system was able for a few hours to remove the bacteria from the circulating blood but was unable to retain and destroy them.

2-deoxyglucose rapidly enters the cells of the extrahepatic tissues in the absence of insulin. Insulin appears to accelerate the intracellular transfer. The intracellular transfer of 2-deoxyglucose inhibits the transfer and oxidation rates of glucose, thus acting as a metabolic block for glucose. It is suggested that the blocking of glucose may take place at the 6-phosphate stage.

In the present study the following compounds offered protection against the diabetogenic action of alloxan: nicotinamide, benzamide, propylene glycol, N-propyl and isopropyl alcohols. The modes of action of these compounds are as yet unknown.

A method is described for the identification and titration of vesicular stomatitis virus which involves the use of the virus, immune serum, fresh horse serum, heat-inactivated bovine serum, and guinea pig erythrocytes. The results obtained using this technic have been shown to be specific.

The diameter of RI-67 virus in infected HeLa culture material was about 109 mu (± 6 mu) determined by pseudo-velocity sedimentation experiments, 80-120 mu based on Gradacol membrane filtration and 90 mu (standard deviation ± 4 mu) shown by electron microscope measurement. Purified preparations of RI-67 and latent adenoid degenerative agent AD-6 contained numerous spherical bodies of uniform size and shape and also a few “doughnut” forms. The CF antigen of infected RI-67 culture fluid sedimented less rapidly than the virus and passed through Gradacol membranes which held back the virus.

It has been demonstrated that 4-aminopyrazolo(3,4-d)pyrimidine (an isomer of adenine), and the 1-methyl derivative of this compound both significantly inhibit the growth of Adenocarcinoma 755 in mice. The former compound significantly increases the life span of mice with L1210 or L5178 leukemia. These compounds represent a new class of purine analogs with significant anticancer activity.

Local application of norepinephrine to the arterial walls of the carotid sinus induced a marked reflex fall of systemic blood pressure, although the carotid sinus walls were deprived of pressure and pulsatile expansion. Changes not in pulsatile expansion but in tone and tension of the barosensitive arterial walls play a primary and fundamental role in the mechanisms of reflex homeostasis of blood pressure.

1. Human bone marrow of a patient with sickle cell anemia and peripheral blood of a normal individual were incubated with iron-59 under similar conditions. Auto-radiograms were prepared from the cells. After incubation, hemolysates of the cells were fractionated by paper electrophoresis and the radioactivity of the fractions was measured. 2. 90% of the total radioactivity was located in hemoglobin from bone marrow hemoly sates. At 37°C the rate of hemoglobin synthesis as measured by iron-5 9 utilization is more rapid in the most immature erythrocytic cells beginning with the rubriblast. The rate of synthesis at 0°C was 25% of that at 37°C. 3. Less than 5% of the radioactive iron in incubated normal peripheral blood was in the hemoglobin fraction.

Treatment of the hemagglutination inhibitor from allantoic fluid with 90% phenol did not result in a low molecular weight active substance. After acetone precipitation, adsorption on indicator virus and ultrafiltration, the partially purified inhibitor was active at 0.5 p.g and the active principle had a sedimentation constant of 15.

The in vitro effects of several groups of compounds were tested on the rate of CO₂ and H₂S evolution, catalyzed by enzyme systems of E. histolytica. Since the mechanism of the enzymatic reduction of S to H₂S, a reaction which is coupled with the anaerobic oxidation of sugars in this proto-zoon, has been previously elucidated, it was possible to classify inhibitors on the basis of their primary point of attack. Certain anti-biotics were found to interfere with the S reducing enzyme system, while compounds which form metal ion complexes inhibit both C0₂ and H₂S evolution to an equal extent. Arsenate and methylene blue on the other hand inhibit primarily C0₂ evolution (the decarboxylation of pyruvate). Certain heterocyclic N containing compounds (e.g., 2, 3-diaminophenazine), which can trap HS° and also form complexes with metal ions were found to be the most potent inhibitors of enzyme systems of E. histolytica. The metabolic reactions which were investigated are specific for this protozoon, therefore inhibitor studies on these enzyme systems are considered to be the biochemical basis of chemotherapy of amebiasis.

In the eviscerate rat depression of complement titer is progressive, reaching 5-10% of normal values by 24 hours.

1. The feeding of a diet containing 0.5% dihydrocholesterol (DHC) for 6 months resulted in the development of severe arteriosclerosis of the thoracic and abdominal aortas in 12 birds. 2. The aortic lesions observed were identical with those induced in the bird by the feeding of cholesterol, and appeared to have resulted from deposition of dihydrocholesterol in the vascular wall. 3. Hepatic enlargement in DHC-fed birds was similar to that observed previously in cholesterol-fed birds, and was due in part to reticuloendothelial storage of dihydro-cholesterol.

The majority of rabbits subjected to single intrapharyngeal infections with group A streptococci developed cardiac lesions characterized by muscle necrosis, cellular infiltration with mononuclear cells and Anitschkow myocytes and disruption of collagen. After multiple infections, fibrosis occurred and giant cells were also observed. Bacteria could not be demonstrated in any lesion. In 3 control groups, comparable lesions were absent in the hearts of all but one rabbit. The appearance of myocardial lesions within 24 hours of induction of pharyngeal infection suggests that a non-immunologic mechanism is involved.

The increases in activity of spleen DNase II following a series of different doses of total-body x-irradiation 24 hours after treatment have been measured. These increases have been correlated with the change in spleen weights associated with the irradiation.

Ovarian adenocarcinoma (human) contains a small amount of the apoenzyme necessary for the oxidation of the 17β hydroxyl group of testosterone. Endogenous estrogens or androgens could not be detected but cholesterol was present at 212 mg/100 g of tumor.

Allantoin and uric acid have been determined in the urines of rats fed a protein-free and 18% casein diet. The animals on the casein diet consisted of a group pair-fed with the animals on the protein-free diet and a group fed ad libitum. The low uri-case activity in the livers of the rats on the protein-free diet was not accompanied by an increase in the uric acid-allantoin ratio in the urine. Thus in the rat it is not possible to predict the in vivo uricase level from the uric acid-allantoin ratio in the urine. However, there is a correlation between the allantoin or the uric acid content of the urine and the uricase content of the liver. Whether there is a relationship between these factors can not be answered at this time.

Cortisone and hydrocortisone act in vitro inhibiting the growth of explanted chick embryo femur anlages. This effect is evident 24 hours after explantation, and increases until the 15th day after the beginning of the experiment. When the hormone is withdrawn at the first transplantation, the anlage recovers active growth and in some instances surpasses the dimensions of the control.

Stimulation of muscle has an insulin-like effect upon the glucose tolerance of the eviscerate rat. In the rat the effect upon glucose tolerance of a combination of muscle work and of optimal doses of insulin is greater than of either one alone. Insulin suppresses the rise in plasma amino acids following evisceration of the rat but muscle work does not.

Lactic dehydrogenase activity of the sera of Swiss and Leaden mice increases promptly after tumor transplantation and decreases with tumor regression.

Subcutaneous injection of the antihistamine Benadryl into 95 female mice, and of Pyrrolazote into 44 female rats, significantly reduced the number of normal pregnancies. The antihistamine acted on the developing fetus, after implantation had occurred.

Studies on the reproductive activity of the adult female rat indicate a marked increase in length of the estrous cycle following exposure to a low ambient temperature. Duration of both the proestrous and estrous stages was increased whereas length of the metestrous and diestrous stages was decreased. Treatment with 50 μg of thyroxine prevented the abnormal changes in the estrous cycle during exposure to cold.

Isolated beef adrenal glands were perfused with homologous blood containing radioactive lysine and amino acids. One preparation of ACTH added to the perfusate was consistent in promoting gland protein synthesis in addition to an elevated corticosteroid output as compared to levels before ACTH addition. These effects were not observed with a different preparation of ACTH.

Data are presented which show that, in several species of bats, erythrocytes are stored in the spleen during hibernation and these are rapidly returned to circulation as the bats become active. This storage accounts for an increase in splenic weight of 500% in Myotis sodalis. Erythrocyte counts are lower in hibernating bats than in active ones.

Under the conditions presented, in the rat, an increase in capillary permeability does not appear to be an important factor governing the transition from the reversible to the irreversible phase of hemorrhagic shock.

1. Hyaluronidase or partially depolymerized hyaluronate enhanced the absorption of subcutaneously injected atropine so that this route was no different from the intravenous with regard to rapidity of onset. 2. Hyaluronidase or partially depolymerized hyaluronate also lowered the minimal effective dose of subcutaneous atropine necessary to antagonize pilocarpine induced salivation, 3. Hyaluronidase applied topically to the cornea shortened the induction time of a local anesthetic at the threshold concentration without affecting the duration of action. Higher concentrations of hyaluronidase abolished the local anesthesia.

1. Disproportionate changes in skull and brain morphology followed the subcutaneous administration of 50 γm/g of cortisone to neonatal rats. 2. The visceral skull vault showed greater retardation than the neural skull vault. 3. The cerebrum and neural skull vault also showed disproportionate dimensional changes leading to increasing brachycephalization. 4. The growing rat brain and molar teeth are competent morphogenic agents. Under these experimental conditions, they are capable of overcoming the relatively greater retardation of related bone, and of thus providing for their own functional protection and support.

Cobaltous chloride was incorporated in the diet of rats in the amounts of 0, 10, 20, 40, 70 and 100 ppm of added cobalt for a period of 19 weeks prior to whole-body x-irradiation and 6 weeks after. The various degrees of polycythemia which were thereby induced were measured indirectly by measuring the increases beyond the normal in hemoglobin concentrations. The ratio of the increase in hemoglobin concentration in each polycythemic group to the normal increase in 14 weeks was found to be directly proportional to the logarithm of the concentration (expressed in ppm) of added dietary cobalt. The rats with cobalt-induced higher concentrations of hemoglobin had an increased average rate of mortality after receiving 750 r whole-body x-irradiation? rather than a decreased rate, as compared with similarly irradiated control rats. Measurements of mucoprotein concentrations in the plasma revealed no significant differences between the various groups before irradiation, nor substantial changes at 48 hours after irradiation.

Influenza B viruses obtained in 1954 and 1955 have been isolated directly in cultures of monkey kidney. The latter system was shown to be preferable to the amniotic sac of the chick embryo for this purpose since more viruses were isolated and only single passages were necessary. Factors have been described which serve to explain the mechanism of these advantages. Growth of these strains was accompanied by cytopathogenic effects in the epithelial cells of monkey kidney cultures.

All portions of the excitability cycle of the dog's ventricle suffer a progressive fall in threshold as body temperature is lowered to 25° under conditions of spontaneous respiration. The decrease in threshold is especially marked in early systole at a point designated as the minor dip. This general increase in myocardial irritability is a reversible phenomenon, the normal excitability recovery curve being reestablished by rewarming to normal body temperature. However, no change in ventricular excitability except at the major dip obtains during hypothermia provided the pH of the blood is maintained at a normal level throughout the cooling process. Both the total “refractory” period and the ventricular conduction time are prolonged during cooling and return to normal during rewarming.

The plasma and urinary amino nitrogen content was studied in dogs exposed to an L. D. 50 (and pair-fed non-irradiated controls) and to an L. D. 100 of x-rays. No significant abnormalities were noted in contrast to the pronounced aminoaciduria reported to occur in man exposed even to small doses of total body radiation.

Cell-free extracts from auto-trophically grown Hydrogenomonas, in the presence of NaHC¹⁴O3 and certain organic acids, are capable of performing the following reactions: 1) To incorporate C¹⁴ into malic acid, in the presence of TPNH or DPNH, pyruvic acid, and Mn⁺⁺ ions; the same is accomplished when malic acid plus TPN or DPN instead of the reduced forms of the coenzymes are used in the above reaction mixtures. 2) To incorporate C¹⁴ into the beta-carboxyl group of oxalacetic acid when NaHC¹⁴O3 is incubated with pyruvic acid, Mn⁺⁺ ions, and oxalacetic acid; ATP is required for this reaction. 3) To incorporate C¹⁴ into isocitric acid when NaHC¹⁴O₃ is incubated with alpha-ketoglutaric acid, Mn⁺⁺ ions, TPNH, or with isocitric acid and TPN in place of TPNH. Cell-free extracts of heterotrophically grown Hydrogenomonas, like the extracts from autotrophically grown cells, are able to accomplish the same reactions.

A number of synthetic peptides representing various sequences occurring in oxytocin have been assayed for strepogenin activity with Lactobacillus casei. Several of these simpler peptides have been found to have high strepogenin activity. As the oxytocin molecule was simplified by the omission of the first two amino acid residues at the terminal amino position, strepogenin activity was not significantly altered. Thus the disulfide of the hfeptapeptide isoleucylglutaminylas-paraginylcysteinylprolylleucylglycinamidehad activity comparable with oxytocin. Further shortening of the sequence from the amino end led to the peptide glutaminylasparag-inylcysteinylprolylleucylglycinamide disulfide with diminished potency; and when the gluta-minyl residue was omitted in addition, activity fell markedly. When amino acid residues were omitted towards the carboxamide end of the active heptapeptide amide disulfide, 2 resulting peptides isoleucylglutaminylasparag-inylcysteinamide disulfide and isoleucylgluta-minylasparaginylcysteinylprolinamide disulfide had low activities. Cleavage of the Cterminal glycinamide residue in vasopressin by the action of trypsin resulted in little change in strepogenin activity although pressor action was destroyed. The bearing of these findings on the question of nutritional requirements for specific peptides has been discussed.

The sera of monkeys infected either intracerebrally or intranasally with poliomyelitis virus exhibts an elevated hyal-uronidase inhibitory activity at the time of, or shortly before paralysis. Those animals infected by the gastro-intestinal route do not demonstrate a similar increased activity over this same period. A reciprocal relationship between the presence of virus neutralizing antibody and the hyaluronidase inhibitory capacity of the serum is noted.

N, N-diethylnicotinamide (Cor-amine), when fed to weanling rats in a 25% protein diet, produced a marked increase in liver size within 3 to 6 days. This enlargement is due, in part, to an average absolute increase of up to 33% in liver protein. The optimal effect is obtained at a dietary level of about 0.5% Coramine. Plasma protein concentrations are slightly higher (5%) in experimental animals than in controls. Paper electrophoretic patterns of the proteins of these plasmas are identical with the patterns of control plasmas. These plasma and liver effects are obtained in a few days when the drug is fed at low dietary levels. Thus it would appear the Coramine acts as a liver growth stimulant in the young rat.

the growth response of strain 19 of Brucella abortus to added metallic ions was studied in a defined medium depleted of metals by chelation with 8-hydroxyquinoline. Fe+ and Mg+ were found to be essential, with the optimal responses at 0.01 and 10.0 μg per ml, respectively. The essentiality of Mn++ was not demonstrated and the optimum at 0.1 μg per ml was indistinct. No intereffects were shown between varying concentrations of Mg++ and Mn++.

E. histolytica has been maintained free of bacteria for 9 days or 3 subcultures in Ringers-Egg-Serum media fortified with the growth factors ribose-5-phosphate, adenosine triphosphate, autoclaved bacterial cells, and diphosphopyridine nucleotide. 2. This method makes available large numbers of amebas (approximately 1 to 1.5 million per ml) free of living bacteria.

Before and during the period of development of the characteristic renal lesions of choline deficiency in young rats consisting of a “hemorrhagic” cortical necrosis, observations were made on renal size, morphologic characteristics of the tubules, lipid content and choline content. These observations emphasize the rapid sequence of events in the development of the renal lesions. While the renal lesions are clearly preceded by a considerable increase in hepatic lipid, we were not able to demonstrate the presence of an appreciable degree of renal enlargement or increased renal lipid, in the absence of renal necrosis. After the onset of the renal lesions, with congestion and necrosis, there was an increase in renal size and in total lipid per kidney, but not in renal lipid concentration. Whether compression of capillaries by enlarged, fatty tubular cells is the cause of the renal necrosis, cannot be determined conclusively, in our opinion, by the methods presently or heretofore employed. It is not clear that the renal fatty changes are a cause rather than a manifestation of injury. Furthermore, it is uncertain whether the fatty changes which accompany the renal lesions result from a metabolic disturbance which might occur in other organs as well, or from some disturbance peculiar to the kidney of the young rat.

Radioactive Krypton 85 was used for the study of renal blood flow and oxygen consumption. 2. Four subjects suffering from acute renal failure were studied during the anuric phase. Renal blood flow and oxygen consumption were reduced to approximately 20 and 25%, respectively, of normal values.

A procedure is described for the isolation of the glycoproteins from spinal fluid that also separates the lipides and free sugars. The carbohydrates in the glycoproteins were identified by paper chromatography, mannose, galactose, fucose, and glucosamine were found. 2. Methods are given for the quantitative estimation of the hexose and hexosamine associated with the glycoproteins and the gamma globulin, and also the neuraminic acid content of the spinal fluid. 3. An increase in gamma globulin hexose was found in multiple sclerosis. The ratio of gamma globulin hexose to glycoprotein was likewise increased. However the ratio of hexose to gamma globulin was not different from that found in non-demyelinating diseases, indicating that the hexose increase merely reflected the increase in gamma globulin.

The LD50 for pentobarbital given intraperitoneally in mice was determined. Administration of picrotoxin within a few minutes of the pentobarbital injection decreased mortality so that the LD50 for the pentobarbital was higher in animals receiving picrotoxin. On the other hand, orally or par-enterally administered hydrocortisone did not decrease mortality and seemed to increase susceptibility to pentobarbital.

Collagenolytic activity was demonstrated in mixed cultures of gingival bacteria from 13 of 19 individuals with chronic marginal gingivitis but from only 3 of 21 individuals with clinically normal gingivitis. This difference is statistically valid. The use of native collagen as a substrate, in the form of tendon, and the determination of the liberation of peptides containing hydroxyproline as an indication of collagenolysis are believed to make the results significant for the situation in vivo. Consequently, it is inferred that gingival bacteria may contribute to the destruction of the collagenous fibers of the periodontium seen in periodontitis.