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Biomedical subjects

J M Navia

Publications and source records attributed to J M Navia.

At least 73 records · Page 4Linked to original sources
PubMed1976

Effective immunity to dental caries: protection of malnourished rats by local injection of Streptococcus mutans.

When rats from dams fed a low-protein diet were injected with whole, killed Strepococcus mutans 6715 cells in the region of the submandibular gland, they developed serum and salivary agglutinins to this microorganism. Titers of agglutinins in malnourished rats were similar to those observed in rats from dams fed a nutritionally adequate diet that were locally injected with S. mutans. Furthermore, both groups of immunized rats subsequently infected with cariogenic S. mutans 6715 had lower mean caries scores than infected, nonimmunized rats. This reduced incidence of caries scores than infected, nonimmunized rats. This reduced incidence of caries was evident on all molar surfaces. The mean body weights of immunized and nonimmunized, protein-deficient rats were not significantly different; likewise, both immunized and nonimmunize normally nourished rats exhibited similar weight gains. Malnourished rats, not immunized but infected with S. mutans, had significantly more caries than normal, nonimmunized infected rats. Both dietary groups of noninfected rats had very few carious lesions. These results suggest that carious lesions observed in these rats resulted from S. mutans 6715 infection. Furthermore, protein-malnourished rats, injected in the region of the submandibular gland with whole, killed S. mutans elicit an immune response and are protected against S. mutans-induced caries.

Animals↗
PubMed1976

Effective immunity to dental caries: studies of active and passive immunity to Streptococcus mutans in malnourished rats.

The present studies suggest that rat dams passively transfer IgG to their offspring via milk. Furthermore, rat dams hyperimmunized to S mutans after intravenous administration of this bacterium have serum-precipitating antibody to S mutans group-specific antigen. This serum precipitin was also observed in serums of their offspring during the suckling period and was detectable for a week after weaning. When these offspring were infected with S mutans on the day of weaning, significantly fewer smooth surface lesions developed in them than in infected rats reared on nonimmunized mothers. These results suggest that anti-S mutans antibody, perhaps of the IgG2a class, is passively transferred from mother to offspring via the milk. Furthermore, this antibody is probably important in protection against S mutans infection. In this regard, recent studies by Lehner, Challacombe, and Caldwell have suggested that crevicular fluid transudating serum antibodies are important in the prevention of dental caries in rhesus monkeys. From our studies and others, it is becoming clear that at least two sources and classes of antibody are important in caries immunity. Secretory IgA, produced and secreted into saliva after local injection can be correlated with protection. At the same time, serum antibody (presumably IgG) either passively or actively derived also gives immune protection. Further studies must clarify the precise role of these Ig's and their possible synergistic activity with other specific immune factors in saliva in order to determine the mechanism(s) involved in effective caries immunity.

Agglutinins↗
PubMed1976

Nutritional implications in wound healing.

Healing of wounds is one of the life functions which is intended as a defense mechanism to maintain the integrity of the body. Understanding basic factors that guide the healing process will help the clinician to propitiate those nutritional measures known to enhance the repair function. Nutrients are normally required for growth, development, and maintenance of the integrity of the tissue. The sum total of the nutritional requirements of all tissues and organs constitutes the requirements of the individual. Recommended dietary allowances have been defined for population groups in the United States for different ages and sex. These allowances involve some 17 different nutrients, but many others (up to 50) are now considered essential, although their exact requirement may not be known. When trauma of any sort is inflicted on an individual, both local and general metabolic changes take place which may lead to nutritional inadequacy. These reactions are normally intended to set into motion the mechanisms designed to repair injured tissues. Nutritional management of the individual requires that the clinican determines what, how, when, and how much nutritional supplementation should be given to the patient. Guidelines for the amounts of proteins, vitamins, and certain minerals to be administered have been discussed. Where there are impediments that make it impossible to feed the patient orally, the clinician should resort to parenteral feeding to insure that nutrients are provided for the convalescing patient. Because the trophic environment will determine to a large extent the speed with which tissues will recover, nutritional care of the patient is important and should be interrelated to the total care of the patient.

Adolescent↗
PubMed1975

Virulence of Streptococcus mutans: a sensitive method for evaluating cariogenicity in young gnotobiotic rats.

Gnotobiotic rats infected with Streptococcus mutans 6715 at 19 days of age and fed a purified diet (305) containing 5% sucrose developed extensive caries lesions on all molar surfaces within 16 days (35 days of age). Approximately twice as many lesions developed when infected rats were maintained until 45 days of age, whereas noninfected rats did not develop caries when fed diet 305. Gnotobiotic rats infected with S. mutans 6715 and fed a purified diet containing no sucrose (300) until day 25 and subsequently fed diet 305 for 10 days developed lesions similar to rats fed diet 305 for 16 days. Furthermore, rats infected with S. mutans 6715 and fed diet 300 until 45 days of age developed approximately one-half the smooth surface lesions as infected rats fed diet 305 for the same length of time. The level of caries on buccal and proximal molar surfaces in 45-day-old gnotobiotic rats varied when animals were infected with S. mutans AHT, BHT, NCTC 10449, 6715, or LM-7. Animals infected with S. mutans AHT showed more severe lesions on the buccal surfaces than those observed in animals infected with the other strains of S. mutans tested, whereas S. mutans 6715 caused significantly more caries on proximal surfaces. On the other hand, rats infected with S. mutans LM-7 exhibited the lowest level of caries on all molar surfaces of the five strains of S. mutans tested.

Animals↗
PubMed1975

Virulence of Streptococcus mutans: biochemical and pathogenic characteristics of mutant isolates.

The in vitro dextran-sucrase activities and adherence to glass of S. mutans 6715 and PS14 wild types and mutants were quantitated and compared with their in vivo cariogenicity in young, gnotobiotic rats. In general, S. mutans PS14 mutants B414 and B421 and 6715 mutant C4 demonstrated less dextran-sucrase activity and adherence than parental strains and caused fewer carious lesions in gnotobiotic rats. Rats monoinfected with either PS14 mutants B414 or B421 had less plaque and viable S. mutans in plaque than rats infected with parental strain. Both S. mutans 6715 mutants C211 and C229, demonstrated greater enzyme activity and adherence than the parental strain and produced more carious lesions.

Adhesiveness↗
PubMed1975

Effective immunity to dental caries: protection of gnotobiotic rats by local immunization with Streptococcus mutans.

Gnotobiotic rats injected in the submandibular region with killed, whole Streptococcus mutans cells developed salivary antibodies directed to this microorganism. Increased levels of salivary IgA and inhibition and augmentation of agglutinin titers with anti-rat alpha-antiglobulin suggested that these antibodies were of the immunoglobulin A class. Furthermore, the rats monoinfected and immunized with homologous organisms always had lower mean caries scores than monoinfected, non-immunized rats. This reduction was evident in carious lesions on the buccal surfaces of molars and in those in sulcal areas. These results suggest that local immunization with whole S. mutans cells stimulates a specific salivary IgA response protective against caries resulting from S. mutans infection.

Agglutination Tests↗
PubMed1971

Effects of actinobolin on growth and some metabolic activities of cariogenic streptococci in vitro and in vivo.

Actinobolin, a known inhibitor of protein synthesis, has been shown not to interfere selectively with acid production or dextransucrase activity in a cariogenic streptococcus when the antibiotic is added to a concentration of 500 mug/ml. It has also been shown that actinobolin does not alter the total in vivo flora of the oral cavity of the rat when tested in a rat caries model system. A culture of cariogenic streptococci, adapted to in vitro growth in the presence of 1 mg of actinobolin per ml, has also been isolated.

Animals↗