Nerve growth factor in skeletal tissues of the embryonic chick.

This study demonstrates, via immunohistochemistry and bioassay, the presence of NGF in embryonic bone and cartilage of the chick. Embryos were killed on days 6-9 of incubation at 12 h intervals, and on days 10-18 at 24 h intervals. Paraffin-embedded sections of hind limbs or buds were immunostained with a polyclonal antibody against NGF and the biotin-avidin-horseradish peroxidase technique.

Selenium and immune cell functions. I. Effect on lymphocyte proliferation and production of interleukin 1 and interleukin 2.

The dietary intake of selenium (Se) has been shown to influence the development and expression of various biologic processes. This study examined the immunologic competence of lymphocytes from C57BL/6J mice maintained for 8 weeks on Se-deficient (0.02 ppm Se), normal (0.

Selenium and immune cell functions. II. Effect on lymphocyte-mediated cytotoxicity.

Selenium (Se) is an essential nutritional factor with a chemopreventive potential. This study examined the ability of C57BL/6J mice, maintained for 8 weeks on Se-deficient (0.02 ppm Se), normal (0.

Isolation of acid producing sorbitol-adapted bacteria from dental plaque using selective agar media.

Acidogenic bacteria metabolizing sorbitol were isolated and identified from dental plaque of twenty nine volunteers, claiming to be users (sixteen) and non-users (thirteen) of sorbitol-containing chewing gum and candy. Sixty bacterial strains were isolated, using improved selective agar media. The taxonomy of twenty strains, all Gram-positive cocci, was determined employing a customized BBL MinitekR system and other biochemical reactions.

Caries protective aspects of saliva and enamel.

Saliva may be considered as being similar to enamel but in a liquid phase. Saliva, the mechanics of remineralization and demineralization, the acquired pellicle and the enamel surface all act to maintain the status quo, resisting mineral loss from the enamel.

A new medium containing antibiotics for the xenic cultivation of Entamoeba gingivalis.

Diamond's trypticase-yeast extract-serum-gastric mucin (TYSGM-9) medium was studied for its suitability to support the xenic growth of the oral protozoan Entamoeba gingivalis. Amoebic growth was found to be best when the inoculum for transfer was 0.1 ml, the incubation temperature was 35 degrees C, and the interval between transfers was 48 h.

The use of denture adhesives as an aid to denture treatment.

Denture adhesives are used by more than five million denture wearers in the United States. All dentists strive to achieve stable, retentive, and comfortable dentures that do not require the use of denture adhesives. However, dentists may prescribe and use denture adhesives as a legitimate therapeutic and effective procedure in denture treatment and in denture aftercare, when indicated.

An important role for cytosol in the microsomal metabolism of N-nitrosodimethylamine to a mutagen: evidence for two different mutagenic metabolites.

Microsomal-mediated mutagenesis induced by N-nitrosodimethylamine (NDMA) in Salmonella TA100 at neutral pH was only slightly affected by cytosol and was similar in its threshold type dose-response curve to mutagenesis induced by direct-acting N-nitroso-N-methyl compounds. However, mutagenesis in strain TA104 was greatly enhanced by cytosol and this mutagenesis did not exhibit a threshold. In the presence of microsomes alone NDMA was more potent in TA100 than TA104, but in the presence of microsomes plus cytosol (S-9 fraction) this order was reversed at the doses tested.

Studies on the microflora associated with xenic cultures of Entamoeba gingivalis.

The microflora associated with xenic stock cultures (ATCC 30927) of Entamoeba gingivalis, the major protozoan of the human oral cavity, were isolated and identified as Citrobacter diversus, Yersinia enterocolitica, Acinetobacter anitratus and Pseudomonas maltophilia. In studies to determine whether the bacterial isolates were able to utilize rice starch as a sole carbon source, Y. enterocolitica exhibited excellent growth in rice starch minimal medium and TYSGM-9 medium (with rice starch), but growth was weak in TYSGM-9 medium (without rice starch).

Mutagenic activity and specificity of N-nitrosomethylaniline and N-nitrosodiphenylamine in Salmonella.

The carcinogenic nitrosamines, N-nitrosomethylaniline (NMA) and N-nitrosodiphenylamine (NDphA), which have been previously reported negative or very weakly mutagenic in the Salmonella/microsome assay, were found to be mutagenic in the hisG428 Salmonella strain, TA104. NMA was moderately potent and NDphA was about 10% as potent. Mutagenesis by both compounds was dependent on the uvrB mutation and enhanced in strains harboring the plasmid, pKM101.

Scanning electron microscopy and electron probe microanalyses of the crystalline components of human and animal dental calculi.

A review of the use of scanning electron microscopy (SEM) and electron probe microanalyses in the study of dental calculus showed that such studies provided confirmatory and supplementary data on the morphological features of human dental calculi but gave only limited information on the identity of the crystalline or inorganic components. This study aimed to explore the potential of combined SEM and microanalyses in the identification of the crystalline components of the human and animal dental calculi. Human and animal calculi were analyzed.

Different mutational profiles induced by N-nitroso-N-ethylurea: effects of dose and error-prone DNA repair and correlations with DNA adducts.

The DNA adducts and mutational profile produced by N-nitroso-N-ethylurea (ENU) in Salmonella are examined. The adduct profile produced by ENU in isolated DNA and at two doses in Salmonella were similar, with one exception: O6-ethylguanine (O6-EtG) was not detected at the low dose in Salmonella. This adduct was presumably repaired by a constitutive repair system.

Ultrastructure of normal human parotid gland with special emphasis on myoepithelial distribution.

The myoepithelium in human parotid, unlike that in other species, is not limited to the acinar-intercalated ductal system but extends to the intra- and extralobular striated ducts. Myoepithelial cells of the striated ducts are smaller, fewer, and different in shape but they are similar in their relationships and ultrastructural morphology to the acinar-intercalated system. Distribution of myoepithelium is discussed with respect to its role and participation in the histogenesis of salivary gland tumours, especially those of intermediate and large duct cell origin.

Autoradiographic investigation of circadian rhythms in alveolar bone periosteum and cementum in young mice.

This report presents circadian rhythms in cell proliferation of alveolar bone periosteum and cementum of the maxillary first molars of male 5-week-old BNL, Swiss albino mice which were maintained on a 12 hr light/dark cycle. Mice were injected with 3H-TDR (luCi/gm. body wt.

Autoradiographic evaluation of circadian periodicity in cell proliferation in the periodontal ligament of the young mouse.

Five-week-old BNL male mice were maintained on a 12-h light/dark cycle, subcutaneously injected with [3H]-thymidine 1 h before death and killed every 3 h for 24 h. Autoradiographs were made from demineralized, paraffin-wax embedded sagittal sections of maxillae. The labelling index was calculated for fibroblast-like cells of the periodontal ligament mesial to the first molar.

An autoradiographic study of the uptake of tritiated proline by osteoblasts during hibernation.

Twenty-four LSH and LVG strain golden hamsters, Mesocricetus auratus, were used. Experimental animals were maintained at 5 C and allowed to hibernate. Control animals were kept at 27 C.

Dental caries vaccine: some problems solved?

The interest in a dental caries vaccine has been great over the past few years. Studies have shown two possible problems using Streptococcus mutans as an immunogen: (i) the production of heart reactive antibody, and (ii) the need to protect against several serotypes. Possible solutions to these problems are discussed.