POCUS for Diastolic Dysfunction: A Review of the Literature

Emergency and critical care physicians frequently encounter patients presenting with dyspnea and normal left ventricular systolic function who may benefit from early diastolic evaluation to determine acute patient management. The current American Society of Echocardiography Guidelines approach to diastolic evaluation is often impractical for point of care ultrasound (POCUS) evaluation, and few studies have evaluated the potential use of a simplified approach. This article reviews the literature on the use of a simplified diastolic evaluation to assist in determining acute patient management.

The Influence of Health Education Teacher Characteristics on Students' Health-Related Knowledge Gains

BACKGROUND

Studies have examined relationships between teacher characteristics and student achievement in courses such as math and science. This study is among the first to examine effects of teacher characteristics on student knowledge in a health course.

METHODS

Student (N = 6143) pretest and posttest data were linked to teacher (N = 67) data. Changes in student knowledge scores from pre- to postcourse were explored using mixed-effects linear models. Teacher characteristics included professional development (PD) attendance, having a dedicated classroom, certification type, educational background, years' experience, and athletic coaching status.

RESULTS

Teacher characteristics associated with greater student knowledge gains included: being certified to teach health versus not certified (p < .001), having a dedicated classroom versus no classroom (p = .017), and for middle school teachers, having attended ≥3 PD sessions versus ≤2 (p = .023). Less knowledge gain was associated with teachers that coached versus noncoaches (p = .040) and having a health degree versus no health degree (p = .049). Post hoc analyses revealed the negative effect of health degree was only significant among coaches (p = .026).

CONCLUSIONS

Findings suggest opportunities for maximizing student knowledge gains through tailored selection of health teachers and provision of appropriate teaching support.

The Evolving Mcart Multimodal Imaging Core: Establishing a Protocol for Computed Tomography and Echocardiography in the Rhesus Macaque to Perform Longitudinal Analysis of Radiation-Induced Organ Injury

Computed Tomography (CT) and Echocardiography (EC) are two imaging modalities that produce critical longitudinal data that can be analyzed for radiation-induced organ-specific injury to the lung and heart. The Medical Countermeasures Against Radiological Threats (MCART) consortium has a well established animal model research platform that includes nonhuman primate (NHP) models of the acute radiation syndrome and the delayed effects of acute radiation exposure. These models call for a definition of the latency, incidence, severity, duration, and resolution of different organ-specific radiation-induced subsyndromes. The pulmonary subsyndromes and cardiac effects are a pair of interdependent syndromes impacted by exposure to potentially lethal doses of radiation. Establishing a connection between these will reveal important information about their interaction and progression of injury and recovery. Herein, the authors demonstrate the use of CT and EC data in the rhesus macaque models to define delayed organ injury, thereby establishing: a) consistent and reliable methodology to assess radiation-induced damage to the lung and heart; b) an extensive database in normal age-matched NHP for key primary and secondary endpoints; c) identified problematic variables in imaging techniques and proposed solutions to maintain data integrity; and d) initiated longitudinal analysis of potentially lethal radiation-induced damage to the lung and heart.

THE PRODUCTION OF AN EXOTOXIN BY CERTAIN STRAINS OF STAPHYLOCOCCUS AUREUS

1. The sterile Berkefeld filtrates of broth cultures of certain strains of Staphylococcus aureus have a selective poisonous action for the skin of rabbits. 2. The poison is thermolabile, being completely destroyed when heated to 55°C for 1 hour. 3. The poison when injected intradermally into rabbits stimulates the production of antitoxin. We therefore conclude that the poison is a soluble toxin.

STUDIES ON BACTERIAL ANAPHYLAXIS AND INFECTION

We have attempted in the preceding experiments the beginning of an analysis of bacterial anaphylaxis and its relation to the occurrences in the animal body during an infectious disease. We have shown that the sensitization of the tissues of guinea pigs, as indicated by the isolated uterus, required 3 to 5 days even when passive sensitization was employed, and that in these relations conditions with bacterial sensitization were entirely analogous to those revealed for serum anaphylaxis by Dale and Weil especially. It has become apparent that the sensitized uterus reacted not at all with whole bacteria or whole red cells, or, in other words, that before reaction with sensitized organs could occur an extraction or solution of the bacterial cell must take place. That bacteria yield some of their substance to the circulating blood during the course of infection was to be expected, but it has been definitely indicated, we think, by our complement fixations. The mechanism of injury in the sensitized animal or in the human being so far along in typhoid fever that antibodies have begun to develop is in part one in which antigen, derived from the bacilli and brought into solution, or rather suspension, in the blood stream, reacts with antibodies which are from the beginning, or have subsequently become, integral parts of the cell protoplasm, the entire process taking place within the cell. This last point is indicated by the failure to sensitize by simply soaking the normal uterus in antiserum. This, however, cannot be the entire story of injury. We know that typhoid antigen injected into normal animals in moderate amounts will render them gradually sick and eventually kill them. Also, a sufficient amount injected into a normal animal will occasionally produce acute symptoms, in every respect similar to the reaction produced in sensitized animals by smaller doses. We have shown that such acute symptoms in normal animals were not due in any degree to tissue sensitiveness, since even very large quantities of antigen will produce no response on the part of the normal uterus. It is reasonable to suppose, therefore, that the injury, gradual or acute, in the normal animal, is in no respect referable to tissue sensitiveness to the whole antigen, but rather must be referred to some series of phenomena which occur in the circulation. The acute shock of normal animals may possibly, therefore, be entirely due to an intravascular reaction. Whether this is one of antigen-splitting, or of antienzyme removal in the sense of Jobling is a point on which these experiments throw no light. It is true that we have never succeeded in producing acute toxic symptoms either in the whole animal or in the isolated uterus with serum from animals acutely ill. This we eliminate as negative evidence inasmuch as we believe that the toxic substances need at no given time be present in the blood stream in sufficient concentration to render such an experiment successful. They are probably absorbed and do their injury almost as rapidly as formed, an assumption which is based on the speed with which symptoms develop. It is possible, and not to be denied on the basis of any experiment that we can devise at present, that the gradual illness of the normal animal and the occasional acute shock of these animals may be based on entirely different mechanisms. In both cases, however, in normal animals, they seem to be intravascular. And since the symptoms of acute shock which can be produced in sensitized animals with moderate doses can also, though only occasionally, be produced in normal animals with larger doses, it is reasonable to suppose that the poisons produced intracellularly in the one may be similar to those produced intravascularly in the other. It does not seem likely that the specific circulating antibodies are in any way sources of increased injury to an animal spontaneously infected with bacteria. If sufficiently powerful at the beginning they may even prevent tissue injury, first by increasing phagocytosis, then by producing intravascular agglutination, and finally, as indicated by our experiments, even by removing a part of the antigen from possible reaction with the cell, though in this last respect our experiments indicate that they functionate imperfectly. It is more probable that their chief protective action to the sensitized body lies in removing the whole bacteria from the possibility of intravascular disintegration, which, as we have shown, is prerequisite to anaphylactic injury of the tissues of the host. We would tentatively summarize our opinion as to the occurrences in the typhoid-infected body as follows: Early injury is probably due to disintegration of part of the bacteria in the course of which albumose-like bodies are liberated, and, following which, intravascular reactions result in the formation of toxic substances, perhaps by some form of proteolysis. Since the accumulation of bacteria during these stages is relatively slight, this form of injury probably plays little part in producing symptoms. Indeed, the experiment by which acute injury is produced in the normal guinea pig by the sudden injection of several times the lethal dose of partly dissolved bacteria, finds no analogy in the spontaneously diseased body. At this time the tissues are not sensitive, but as antigen absorption progresses and the tissues are stimulated to react, sensitiveness develops, which renders them much more delicately amenable to injury by direct reaction with even small amounts of dissolved but otherwise unaltered antigen. This process is directly counteracted by circulating antibodies which tend to remove the bacteria from the possibility of yielding their antigen to solution by agglutinating them, aiding phagocytosis, and to a slight extent even neutralizing dissolved antigen. It seems likely, therefore, that the symptoms which appear as the incubation time ends are largely those due to cellular sensitization which probably begins before any considerable amount of circulatory antibodies is present. The circulating antibodies would seem to have little or nothing to do with intravascular injury, the ferments responsible for this, however much it may occur, probably consisting of the non-specific proteases studied in this connection by Jobling. Finally it appears that highly sensitized animals are more easily killed by typhoid antigen than are normal animals, provided they do not dispose over unusually large amounts of circulating antibodies. Cure would consist of a gradual checking of growth and final destruction of the bacteria, and the consequent cessation of antigen liberation, but delicate hypersusceptibility would probably persist for some time after cure and immunity have been established. Just what the relation between tissue hypersusceptibility and immunity is remains a problem for further study.

THE EFFECT OF INJECTIONS OF HEMOLYTIC STREPTOCOCCI ON SUSCEPTIBLE AND INSUSCEPTIBLE ANIMALS

1. Streptococci injected into the circulation of cats are quickly withdrawn and are found most numerously in the lung, less numerously in the liver and spleen, and in small numbers in the bone marrow, lymph nodes, muscle, and kidney. 2. The streptococci taken up by the lung are killed within 5 to 8 hours, although they remain visible in films for a number of days. In the liver they are killed less rapidly, and in the spleen a few may remain viable for a considerable period. 3. This bactericidal action may be demonstrated in pieces of excised lung but not in lung extracts, and is apparently dependent on the action of the living cell. 4. Streptococci injected into a susceptible animal, the rabbit, are also promptly removed from the circulation, but are distributed in different proportions, the liver and spleen absorbing almost as many as the lung, and the muscles also taking up an appreciable number. 5. As in the cat, the organisms taken up by the lung and liver of the living rabbit are promptly killed. Those which lodge in the muscles, however, multiply rapidly. 6. About the time that the streptococci have begun to develop in the muscles (4 to 8 hours after injection) the number in the blood stream begins to increase. 7. The increase in the blood stream is not due to exhaustion of the mechanism of their removal nor have these organisms acquired a resistance sufficient to maintain them in the blood stream of a normal animal. The septicemia, then, is probably the resuit of washing out of organisms from the infected tissues. 8. Attempts to immunize rabbits have been unsuccessful, but in certain treated animals the distribution of the organisms among the various organs approached that found in insusceptible animals; i.e., cats.

FURTHER STUDIES ON BACTERIAL HYPERSUSCEPTIBILITY. II

When filtered alkaline extracts of pulverized bacteria of several varieties are precipitated with acid in the cold, boiled with acid, and all materials thrown down by these procedures removed, there remains a small amount of an alcohol-precipitable material which no longer gives any of the ordinary chemical reactions for proteins, such as the biuret, Hopkins-Cole, Millon, and sulfosalicylic acid reactions. The only protein reaction usually given by this material is a very weak xanthoproteic reaction. Nevertheless, the material, which is, as far as we can determine at present, free from coagulable protein, is specifically precipitable by homologous antiserum and gives specific complement fixation reactions. Such material can also be obtained from organisms like the influenza bacillus, pneumococcus, and meningococcus by extraction without preliminary grinding of the bacteria, and is present in filtrates of young and old broth cultures of the organisms. We believe that these acid- and heat-resistant antigenic materials are analogous to tuberculin and to the pneumococcus substances with which Dochez and Avery (6) made their observations some years ago. The stability of these substances is considerable and was investigated particularly because we thought this represented an indirect method of eliminating the possibility of their protein nature. In all cases boiling in a reflux condenser at an acid reaction ranging from pH 5 to 6 for 1 hour failed to destroy the antigenic specificity of the residue antigens. After such treatment satisfactory and specific precipitation reactions could be obtained. Similar boiling in alkaline reactions, however, destroyed the precipitability of staphylococcus and influenza residues. Subjected to autoclave digestion at an acid reaction of pH 5.4 for 1 hour at from three to four atmospheres, none of the antigenic residues investigated, except that obtained from the influenza bacillus, were destroyed. The pneumococcus and tubercle bacillus residue antigens were resistant to boiling for 1 hour, both in acid and alkaline reactions (pH 5.4 and 9.4). In fact, none of the procedures resorted to made any difference with these two last mentioned substances. It would seem that these facts would add considerable weight to the assumption that the materials dealt with were not ordinary whole proteins. On preservation in the ice box at an alkaline reaction of pH 9.4, the influenza residue deteriorated within 48 hours, but the other antigens withstood similar treatment for 6 days. In spite of the fact that these residue antigens were precipitable by homologous sera produced by immunization with the whole bacteria or their unfractionated extracts, we have so far failed to produce antibodies in animals by injecting these residues. While this may be due to inability to inject sufficient amounts of the material it still suggests strongly the possibility that we may be dealing with substances that are antigenic only in the sense that they are able to react with antibodies, but are themselves incapable of inciting antibody production. We suggest, in this connection, the possibility of the relationship between the power of antibody production and molecular size. This phase of the work is being continued on a more extensive scale. Our work on the reactions of the residue materials in infected animals indicates, as far as we have gone, that complete analogy exists in this respect between the conditions prevailing in guinea pigs infected with these organisms and those previously elucidated for tuberculous animals. This is in keeping with previous knowledge concerning the analogies between the mallein and tuberculin reactions and the studies on skin hypersusceptibility in Bacillus abortus- and typhoid-infected guinea pigs reported by Meyer and his coworkers. It would seem from all these facts that, in guinea pigs infected with bacteria capable of forming foci in the body, infection is followed within a variable, but relatively short time (5 days to 2 weeks) by a type of hypersusceptibility which is distinct from protein anaphylaxis and which may be determined by intradermal skin reaction. It appears likely that the growing bacteria elaborate in the animal body a metabolic product, possibly not a whole protein, which, though practically non-toxic to normal animals, may become highly and specifically injurious to the infected ones. Such a conception, if further confirmed, would lead to greater clearness in our comprehension of the toxic effects occurring in infections with organisms not true exotoxin producers and, judging by the cellular injuries observed in severe skin reactions, may easily explain focal necrosis and the deeper cellular degenerations observed in the course of many bacterial diseases. The general bearing of this work upon conceptions of hypersusceptibility is obvious and has been briefly discussed in another paper. Its chief significance is in holding out the hope that we may be able to elucidate the mechanism of a type of specific hypersusceptibility in which the antigen concerned is not a coagulable protein and in which the laws of sensitization in regard to time and quantity differ from those recognized in true protein anaphylaxis. It seems likely that a recognition of the fact that physical and chemical differences in the substances leading to various forms of specific hypersusceptibilities in the animal body must necessarily influence the mechanism of sensitization, may furnish a clue to further investigations. As such materials become simpler in structure, they fail to induce typical antibody production and by gradually increased diffusibility transfer the reactions from the cell surface to the interior of the cell. The extremes of the scale of differences would be represented by protein anaphylaxis, on the one hand, and drug idiosyncrasies, on the other. Although this suggestion is largely speculative, it has seemed worth mentioning as a line of reasoning suggested by our work. Incidentally, these studies may indicate the usefulness of the residue antigens for specific precipitation and complement fixation reactions for routine purposes in laboratory investigations.

ENVIRONMENTAL AUDITING: Chemical Characteristics of Urban Stormwater Sediments and Implications for Environmental Management, Maricopa County, Arizona

/ Investigations of the chemical characteristics of urban stormwater sediments in the rapidly growing Phoenix metropolitan area of Maricopa County, Arizona, showed that the inorganic component of these sediments generally reflects geologic background values. Some concentrations of metals were above background values, especially cadmium, copper, lead, and zinc, indicating an anthropogenic contribution of these elements to the sediment chemistry. Concentrations, however, were not at levels that would require soil remediation according to guidelines of the U.S. Environmental Protection Agency. Arsenic concentrations generally were above recommended values for remediation at a few sites, but these concentrations seem to reflect geologic rather than anthropogenic factors. Several organochlorine compounds no longer in use were ubiquitous in the Phoenix area, although concentrations generally were low. Chlordane, DDT and its decay products DDE and DDD, dieldrin, toxaphene, and PCBs were found at almost all sites sampled, although some of the pesticides in which these compounds are found have been banned for almost 30 years. A few sites showed exceptionally high concentrations of organochlorine compounds.On the basis of published guidelines, urban stormwater sediments do not appear to constitute a major regional environmental problem with respect to the chemical characteristics investigated here. At individual sites, high concentrations of organic compounds-chlordane, dieldrin, PCBs, and toxaphene-may require some attention. The possible environmental hazard presented by low-level organochlorine contamination is not addressed in this paper; however, high levels of toxicity in urban sediments are difficult to explain. Sediment toxicity varied significantly with time, which indicates that these tests should be evaluated carefully before they are used for management decisions.

BMEC-1: a human bone marrow microvascular endothelial cell line with primary cell characteristics

Bone marrow microvascular endothelial cells (BMEC) are a functional component of the bone marrow stroma and have been shown to release hematopoietic regulatory factors as well as to selectively adhere and support the proliferation and differentiation of CD34+ hematopoietic progenitors. An early passage of these cells was immortalized by transfection with a vector (pSVT) encoding the large T antigen of SV40. The transformed cell line (CDC/CU.BMEC-1) expresses the SV40 transcript, retains the primary cell expression of Ulex europeaus and vWF/ FVIII, and incorporates acetylated low-density lipoprotein. In addition, BMEC-1 mirrors the phenotype of the primary cells with only a few exceptions. Both cell populations express the cellular adhesion molecules ICAM-1 and PECAM and also VCAM-1 and ELAM-1 after upregulation by tumor necrosis factor-alpha. The fibronectin receptor, hyaluronate receptor, collagen receptor, integrins VLA-alpha 3, VLA-alpha 4, and beta 4, endoglin, collagen IV, CD58, and CD61 are also expressed. The only differences are that BMEC-1 expresses higher levels of ICAM-1, CD58, CD34, CD36, and c-kit than the primary cells. The supernatants of primary cell and BMEC-1 contain stem cell factor, interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1 alpha, IL-11, and G-CSF. The functional significance of these hematopoietic cytokines was demonstrated in transwell cultures. Both cell populations supported the expansion of progeny from CD34+ cell-enriched cord blood mononuclear cells suspended in the upper chamber. These characteristics, plus the fact that BMEC-1 can be maintained independently of exogenous growth factors and exhibit contact inhibition, indicate that this cell line can be used to further define the role of BMEC in hematopoiesis.

Selective inhibition of adhesion molecule expression by edelfosine (ET-18-OCH3) on human umbilical vein or microvascular endothelium

An abundance of data is accumulating that suggest that if one can block endothelial cell-leukocyte binding or inhibit cell adhesion molecules (CAM), inflammatory events can be greatly diminished. In this report, we demonstrate that an alkyl-lysophospho-lipid compound (ET-18-OCH3) can decrease adhesion molecule expression on cultured human micro- and macrovascular endothelial cell lines. ET-18 selectively decreased CAM expression; CD31 was decreased, however. Vascular CAM-1 tumor necrosis factor-alpha-induced expression was not altered. Intercellular adhesion molecule 1 expression was decreased, but endoglin expression was not affected. Thus, we have demonstrated nontoxic downmodulation of vascular CAM expression in vitro. Whether this compound will have anti-inflammatory properties needs to be clarified in animal models.

Panendoscopy in screening for synchronous primary malignancies

The entire upper aerodigestive tract must be evaluated at the time of initial tumor evaluation in patients with squamous cell carcinoma of the head and neck. The necessity of panendoscopy (laryngoscopy, bronchoscopy, esophagoscopy) in this evaluation has not been demonstrated convincingly. Between January 1, 1984 and December 31, 1985, 208 patients with previously untreated squamous cell carcinoma of the head and neck were analyzed prospectively. These patients underwent head and neck examination, chest radiograph, barium esophagram, and panendoscopy. Fifteen (7.2%) had synchronous malignancies of the upper aerodigestive tract. In four patients (1.9%) the synchronous primary tumor was found only by endoscopy. Three patients (1.4%) had cancers of the hypopharynx. One patient (0.5%) had a bronchial cancer detected only on bronchoscopy. No tumors were detected by esophagoscopy that were not also seen on barium esophagram. We conclude that endoscopic examination of the hypopharynx is very helpful in screening for additional tumors in head and neck cancer patients, but routine esophagoscopy cannot be supported. Screening bronchoscopy cannot be strongly supported due to its very low yield.

EXPERIMENTAL PNEUMONIA IN GUINEA PIGS : II. EFFECT OF ANTI-AUTOLYSATE SERA ON PNEUMOCOCCUS PNEUMONIA IN GUINEA PIGS

1. Anti-pneumotoxic sera prepared in rabbits or horses by immunization with sterile filtrates of the pneumotoxin, under certain conditions protect against the pneumonia caused by the intratracheal injections of mixtures of living pneumococci and toxic autolysates. 2. The protection against the development of pneumonia is heterologous, at least as regards Type I, Type II, viz.: an anti-autolysate serum prepared by the immunization with a pneumotoxin from one type of pneumococcus will prevent the development of pneumonia caused by the injection of pneumococci and autolysate from another type. 3. Certain anti-pneumococcus horse sera used in the treatment of pneumonia in man, either contain no heterologous pneumonia-preventing antibodies or slight amounts only. These sera, however, protect against the pneumonia produced by injections of pneumococci and pneumotoxin of the homologous strain, the degree of protection depending on the amount of specific protective substances such sera contain. 4. Anti-pneumotoxic sera produced in rabbits or horses by the injection of sterile Berkefeld filtrates of the toxic autolysates contain no pneumococcus specific protective substances.

THE PRODUCTION AND TITRATION OF POTENT HORSE ANTIPNEUMOTOXIN

1. The serum of horses immunized with increasing doses of certain anaerobically produced autolysates of pneumococci contain potent neutralizing antibodies for the pneumotoxin. 2. The method for the in vitro titration of these horse antipneumotoxic serums is given.

DIFFERENTIATION BETWEEN SOME TOXIC SUBSTANCES IN ANAEROBICALLY PRODUCED AUTOLYSATES OF PNEUMOCOCCI (TYPES I AND II)

The necrotizing and lung-toxic principles present in certain anaerobically prepared autolysates of Pneumococcus Types I and II are similar in respect to extreme sensitiveness to heat and to oxidation, and to their ability to be neutralized by the same anti-autolysate serums. These two poisons differ, however, in their ability to be adsorbed or inactivated by red cells; the lung-toxic principle being adsorbed or inactivated by such procedure while the necrotizing principle is not. Since pneumococcus hemotoxin is present in the anaerobic autolysates and is also adsorbed by red cells, it seemed possible that it was this substance in the autolysates which caused the diffuse lung lesions and death of guinea pigs. However, it was found that the intratracheal injection of pneumococcus hemotoxin prepared by the method of Avery and Neill only occasionally produced the characteristic reaction caused by the intratracheal injection of the anaerobic autolysates.

EXPERIMENTAL PNEUMONIA IN GUINEA PIGS : I. THE EFFECT OF CERTAIN TOXIC AUTOLYSATES OF PNEUMOCOCCI

1. Anaerobic autolysates of pneumococci, prepared according to the method described, are highly toxic for guinea pigs when injected intratracheally in dosage of 0.2 cc. Death occurs either within a few hours (36 per cent) or within 3 days. In the early deaths there is intense hemorrhagic edema of the lungs with beginning inflammatory reaction; in animals surviving for 18 hours or longer extensive areas of pneumonia are produced. 2. The intratracheal injection of virulent living pneumococci is followed by transient slight lesion with recovery, or by later death from septicemia without pneumonic lesions. 3. The addition of a sublethal dose of toxic autolysate to living pneumococci alters the reaction of the animal, so that there develops extensive pneumonia associated with unrestrained multiplication of the organism.

THE PRODUCTION OF SKIN NECROSIS BY CERTAIN AUTOLYSATES OF PNEUMOCOCCUS (TYPES I AND II)

1. Certain pneumococcus autolysates produce necrosis when injected into the skin of guinea pigs. 2. The necrosis-producing principle can be filtered through a Berkefeld N filter, is extremely thermolabile, and is very sensitive to oxidation. 3. The necrotizing poison can be separated from the pneumococcus hemotoxin by adsorption with red cells. This removes the hemotoxin and leaves the necrosis-producing principle unaffected. 4. The necrotizing substances obtained from Pneumococcus Types I and II are neutralized by the antiserum prepared with Pneumococcus I.

A SPECIFIC POISON IN THE LIVER EXTRACTS OF RABBITS INOCULATED WITH TYPHOID AND PRODIGIOSUS BACILLI INTRAVENOUSLY

1. The livers of rabbits inoculated with cultures of Bacillus typhosus or Bacillus prodigiosus under certain conditions contain a toxic substance extractable with salt solution. When the toxic extracts are injected intravenously into normal rabbits the latter animals develop symptoms resembling those of anaphylactic shock and succumb. The lethal doses of the toxic extracts are far smaller than those of normal liver extract. 2. The livers of rabbits injected with typhoid antigen also yield a toxic extract. 3. Boiling as well as filtration through a Berkefeld filter only partially detoxicates the extract. 4. Tolerance to one to two lethal doses of the poisonous extracts can be induced by cautious immunization. 5. Rabbits actively immunized to Bacillus typhosus or Bacillus prodigiosus usually resist one lethal dose of the homologous liver poison; and animals tolerant to the typhoid liver poison resist one minimum lethal dose at least of Bacillus typhosus. 6. Typhoid immune serum is not detoxicating either in vivo or in vitro for the typhoid liver poison. 7. The liver poisons are specific, since rabbits actively immunized to either Bacillus typhosus or Bacillus prodigiosus withstand at least one minimum lethal dose of the homologous but not of the heterologous-liver poisons.