Matthew C. Dodd

A Study of the Bacterial Flora of Caries-Susceptible and Caries-Immune Saliva

SEVERAL types of bacteria have been associated with the etiology of caries, most commonly streptococci and lactobacilli, which are both acidogenic and relatively aciduric. Streptococci are more numerous in saliva and plaques, 2 but lactobacilli are capable of producing a lower pH in media. Furthermore, the relationship between high numbers of salivary lactobacilli and low pH minima in plaques,3 and the correlation between the continued presence of relatively high numbers of salivary lactobacilli and caries activity associate these organisms with the decay process.4 Considerable work has been done to determine whether streptococci or lactobacilli are more intimately associated with caries, and the work has been recently reviewed by Rosebury5 and Harrison.6 A number of adults apparently completely resistant to caries, have been termed immune since they have no history of this disease. This immunity has not been associated with age, sex, race, or dietary habits, but there is some evidence suggesting a genetic factor in caries resistance.7 In terms of the acidogenic theory of caries, it must be assumed that the organisms responsible for caries in susceptible persons are absent from immune mouths, or that the acidogenic activities of such organisms are either modified or neutralized in immune mouths. This last would imply the operation of some mechanism in the immune mouth which inhibits or modifies the activities of potentially cariogenic organisms. It has been previously shown by several investigators that salivary lactobacillus counts in immunes are very low and may be nonexistent in many subjects,4 8 while counts of streptococci are nearly the same in both immune and caries-susceptible salivas. The purpose of the investigations presented here is to compare the salivary microflora of caries immunes and susceptibles and to study the effect of saliva upon certain oral organisms in vitro, for indications of possible mechanisms of immunity to dental caries.

Comparative Microflora of Developing Dental Plaques in Caries-Immune and Susceptible Individuals

WVIILLIAMS1 and Black2 were among the first investigators to develop genN erally acceptable theories concerning the composition and activity of the masses of microorganisms called dentobacterial plaques on human teeth. They considered that plaques were prerequisite for caries initiation, and that differences between cariogenic and noncariogenic plaques were due to differences in the potentialities of the bacterial populations. Modern concepts generally include these ideas.

Specific inhibition of RHo(D) antibody by sialic acids.

Agglutination of RhO(D) erythrocytes by specific antiserum was inhibited by crude and crystalline N-acetylneuraminic acid, less inhibited by its glycoyl derivative, and weakly inhibited by its degradation product, N-acetyl-mannosamine, and by D-mannose. A brain ganglioside containing neuraminic acid and a Pseudomonas polysaccharide were even more inhibitory. Inhibition was specific for anti-D sera.

IMMUNOGENIC RNA IN THE IMMUNOTHERAPY OF CANCER: THE TRANSFER OF ANTITUMOR CYTOTOXIC ACTIVITY AND TUBERCULIN SENSITIVITY TO HUMAN LYMPHOCYTES USING XENOGENEIC RIBONUCLEIC ACID*

The transfer of tumor immunity using RNA extracted from immunized animals has been demonstrated within syngeneic systems.’. The interspecies transfer of DTH and of antibody production has also been l2 We n p > ? and others 2 have noted the transfer of DTH using RNA from xenogeneic sources to human lymphocytes. In addition, it appears that the transfer agent of nondialyzable transfer factor may be IRNA.2 As reported earlier,” the use of IRNA offers several advantages in immunotherapeutic approaches to the treatment of cancer. The general approach to cancer immunotherapy using immunogenic RNA is shown in FIGURE 1. Tumor material or extracted tumor antigen is injected into a suitable experimental animal, and RNA extracted from the animal’s lymphocytes. The patient’s lymphocytes are treated with this immunogenic RNA in vitro, and tested for immunological reactivity against the tumor. These autochthonous cells are then returned to the patient. This report is concerned with the transfer of tumor cytotoxicity as well as delayed hypersensitivity to hu,man peripheral blood cells using xenogeneic RNA. The experimental results to be reported here, together with those of others workers in the field, should establish the basis for initiating an intensive effort to develop methods for applying immunogenic RNA to the treatment of human cancers.

A Sensitive and Reproducible Assay for the Quantitation of the MIF Correlate of Delayed Hypersensitivity in Man

An improved migration inhibitory factor (MIF) assay procedure is described which was developed for the study of tumor patient immunocompetence testing both on the clinical level and as an adjunct to basic studies of tumor immunology and the transfer of immunological capacity through immuno-genic RNA. A detailed description of a new migration chamber in which as many as eight capillaries can be simultaneously subjected to identical environmental conditions is presented, This feature reduces the variation among replicate tests to the point where significance can be ascribed to migration differences of ten percent or less. This chamber, along with the use of a cultured human lymphoblastoid tumor cell as the indicator cell, results in a very flexible, convenient, and sensitive direct or indirect assay for the detection of human migration inhibitory factor.

Induction of isoantibodies to human leukocytes.

As an exploratory first step toward the production of leukocyte antisera of circumscribed and predictable specificity, 10 volunteers were immunized, each to the leukocytes of a single donor. Washed leukocyte suspensions were injected i.d. and i.m. and in four instances, transfusions were given. All the volunteers developed leukoagglutinins and complement-fixing antibodies to leukocytes in 40–293 days. These antibodies persisted for 72–223 days after the final injection. Seven of the 10 developed complement-fixing antibodies to the donors platelets. The induced antisera have been used for leukocyte grouping of other normal subjects.

THE ROLE OF PARACOLOBACTRUM AND PROTEUS IN INFANTILE DIARRHEA

Probably the outstanding feature of the literature on the early bacteriology of infantile diarrhea is the consistent indication of the diverse etiology of this disease. The more recent recognition of the enteropathogenic Escherichia coli and its causal relationship to certain outbreaks of infantile diarrhea, adequately presented elsewhere in this monograph, has added still another bacterial species to the already long list of possible incitants of this clinical entity. The probability that one or more viral agents may also have to be included in the near future is indicated by other studies published in this monograph. Time does not permit even a listing of the variety of bacterial species incriminated, at one time or another, as the cause of diarrhea in infants. It should be sufficient to note that members of such divergent genera as Pseudomonas, Alcaligenes, and Staphylococcus, as well as various types of enterococci, have been reported in sporadic or epidemic outbreaks. Prior to 1945, however, the agents most frequently reported, aside from the classical Salvzonella and Shigella, were Paracolobactrurn and Proteus. The purpose of this presentation is to attempt to evaluate the role of these two groups in infantile diarrhea. The major obstacle encountered is the lack of any clear-cut demonstration of pathogenicity by these organisms for the gastrointestinal tract of the newborn. The alternative is to consider the evidence that has accumulated, almost since the original identification of these organisms, in the form of clinical, bacteriological, and epidemiological observations linking Paracolobactrurn and Proteus to outbreaks of infantile diarrhea. This is made difficult, especially in some of the early reports on Paracolobactrum, by the problems of classification. In addition, the knowledge that methods for the identification of the enteropathogenic strains of E. coli were not available makes it obvious that the investigations of the bacteriology of some of these reports could not have been complete and thus, to some extent, questions their validity. The latter problem is exemplified by the experience reported by Neter’ in 1952 with stools obtained from two outbreaks of infantile diarrhea that had occurred in upper New York State in 1947. Previously, cultures of these stools had produced no evidence of the presence of any known pathogenic enteric bacteria, and attempts to isolate a virus, carried out in the laboratories of the New York State Health Department in Albany, N. Y., were unsuccessful. Fortunately, fecal samples had been frozen and, five years later, cultures of E. coli, 0111 were obtained from five of the seven samples. Almost from the time of their first recognition, so-called “paracolon” bacilli have been associated with infantile diarrhea, and although exact identification by the methods employed in early reports is impossible, there is little doubt that these refer to Paracolobactrum. There is also little doubt as to the authors’ conclusions as to the etiologic roles of these agents in the disease. Thus, as far back as 1893, paracolon bacilli were described by Gilbert and Lion2 in Eng-

Effect of temperature and humidity on nasal flora of mice.

Summary The count of the normal bacterial flora of the nasal cavity was markedly reduced when mice were maintained under low humidity for three weeks, whereas no significant change was observed under high humidity. The reduction was noted mainly in the gram positive organisms.

Interstrain Resistance to Polyoma Virus Oncogenesis and Runting in Inbred Mice Treated with Antilymphocyte Serum (als)

Summary Newborn DBA/2 mice and C57/BL mice were inoculated at various times in the postnatal period with either polyoma virus, antilymphocyte sera (spleen cell), or both. The DBA/2 mice runted and died in 2-3 weeks when virus and ALS were given within the first week of life. The C57/BL mice treated the same way did not die and some runted temporarily. All DBA/2 mice which received ALS and virus within the first 2 weeks developed malignant parotid gland tumors within 19 weeks after birth. The onset of tumor development was related to the time of ALS treatment. Only C57/BL mice which received ALS and virus within 3 days of birth developed tumors. Early killing, runting, and tumor production in DBA/2 mice and tumor development in C57/BL mice appear to be associated with the developmental level of the animals.