Damage and repair of DNA in cultured mammalian cells with N-diazoacetylglycine amide.

N-Diazoacetylglycine amide, a diazochetoalkane, has been studied in vitro for DNA damage and repair in cells of a cloned subline from a BALB/c mouse. To our present knowledge, none of these compounds have been investigated for such activities. At nontoxic levels, a prolonged dose-dependent unscheduled DNA synthesis was observed by autoradiography. DNA damage was studied by sedimentation through alkaline sucrose gradients after the cells were lysed on the gradients. Treatment of the cells for 1 hr with nontoxic doses of N-diazoacetylglycine amide resulted in slower sedimentation of DNA. The number of single-strand breaks appeared rather linearly dose dependent for a large range of concentrations. Breaks were at their maximum after 1 hr of treatment, and no further increase in the number of breaks was seen. Some repair of the breaks probably occurs, but repair was sluggish even 68 hr after treatment. A significant part of the breaks was observed after incubation at 4 degrees in an ethylenediaminetetraacetate hypotonic solution. This seems to indicate that the compound does not require metabolic activation. Nontoxic doses of N-diazoacetylglycine amide and other similar derivatives exert mutagenic and carcinogenic activities. The presence of DNA damage and the difficulty in its repair at such doses could be related to both of these biological properties.

Oral digestion of a complex-carbohydrate cereal: effects of stress and relaxation on physiological and salivary measures.

A comprehensive study was undertaken with 12 dental hygiene students to ascertain whether the time of chewing or the degree of relaxation is more important in the oral digestion of complex carbohydrates. In addition, we studied whether the effects of stress and relaxation on salivary alpha-amylase activity was corroborated by physiologic measures. The dental hygiene students chewed an oat cereal for either 20 or 60 s while under two different orders of stress and relaxation conditions: 1) stress/20 s, stress/60 s, relax/20 s, relax/60 s; and 2) relax/20 s, relax/60 s, stress/20 s, stress/60 s. Galvanic skin resistance, pulse rate, and blood pressure (systolic and diastolic) were used to physiologically verify the effects of stress and relaxation on amylase activity. Amylase activity was judged by spectrophotometric analysis of maltose produced from a specific dilution of expectorated saliva. Results showed that the physiological measures significantly corroborated the salivary determinations of stress and relaxation and that deep relaxation was significantly more important than thorough chewing in the oral digestion of complex carbohydrates.

The effects of dietary tryptophan on chronic maxillofacial pain and experimental pain tolerance.

This study investigated the effects of daily administration of three grams of tryptophan in conjunction with a high carbohydrate, low fat, low protein diet on chronic maxillofacial pain, experimental pain thresholds, and anxiety and depression. In a double-blind study, 30 chronic pain patients were randomly assigned to a tryptophan or placebo group. At the initial appointment and 4 weeks later, the patients' subjective ratings of their pain were recorded, electrical tooth pulp stimulation was used to measure pain thresholds, and psychological tests of depression and anxiety were administered. Over the 4 weeks of the study, there was a greater reduction in reported clinical pain and a greater increase in pain tolerance threshold in the tryptophan group than in the placebo group. The group did not differ in anxiety and depression--for all subjects there was lowered depression and anxiety over the 4 weeks of study.

The comparative analysis of clinically normal and inflamed human gingiva. Study 1: Protein separation by anionic and cationic disc gel electrophoresis.

Homogenates were prepared from sections of both clinically normal and clinically inflamed human gingival tissue. After centrifugation, supernatants were quantitated for protein and subjected to anionic and cationic electrophoresis. Samples of gingival blood and venous blood were similarly subjected to electrophoresis. Significant protein pattern differences are reported for the anionic tissue separations, and for the cationic tissue and plasma separations.

Zinc-induced suppression of inflammation in the respiratory tract, caused by infection with human rhinovirus and other irritants.

Free ionic zinc (Zn2+) in saliva shortens duration and severity of common cold (CC) symptoms. It is proposed that Zn2+ complexes with proteins of critical nerve endings and surface proteins of human rhinovirus (HRV) (a) interrupt nerve impulses and (b) block docking of HRV on intercellular adhesion molecule-1 (ICAM-1) on somatic cells, thereby interrupting HRV infection. Since leukocyte function associated antigen-1 (LFA-1) binds leukocytes to cells through ICAM-1, initiating inflammation, Zn2+ is expected to block LFA-1/ICAM-1 binding and thereby suppress inflammation. This could explain reduction of inflammation experienced by persons taking zinc gluconate/glycine (ZGG) lozenges for CC. Allergic rhinitis (AR) and CC share many common symptoms, and ZGG also mitigates AR symptoms. Focal irritation, increased ICAM-1 expression, and recruitment of leukocytes to epithelial foci are the common elements. Zinc ions may be an important anti-inflammatory factor because they can block docking of both HRV and LFA-1 with ICAM-1.

Esthetic management of perimolysis with porcelain laminate veneers.

This report deals with the dental manifestations of bulimia nervosa. Differential diagnosis of perimolysis was identified and compared with other manifestations of systemic or exogenous causal factors. Conservative cosmetic dental management of the dental erosion that occurred as a result of bulimia nervosa was described and discussed in comparison with other currently accepted treatment modalities.

Sugars present in tobacco extracts.

The presence of fructose, glucose, sucrose, maltose, and isomaltose in commercial tobacco products was identified and quantitated. Gas-liquid chromatographic studies showed that these five types of sugar were present in the water-soluble extracts of pouch and plug chewing tobacco, yet only fructose and glucose were found in extracts of snuff and unprocessed natural tobaccos. The amount of sucrose present in pouch chewing tobacco was twice that in plug chewing tobacco. No detectable amount of sucrose was found in snuff or unprocessed natural tobaccos. The content of maltose and isomaltose was much less than the content of fructose, glucose, or sucrose. All unprocessed natural tobacco leaves studied as controls contained low amounts of fructose and glucose, and no detectable amounts of sucrose, maltose, or isomaltose. The larger amounts of fructose and glucose, and the additional sucrose, maltose, and isomaltose present in pouch and plug chewing tobaccos are probably added during the manufacturing process.

Sugar and fluoride content of various forms of tobacco.

Previous studies have produced conflicting reports about the possible relationship between the chewing and smoking of tobacco and the incidence of caries. This study identifies the total sugar and the fluoride concentrations of various forms of tobacco from different areas of the United States. This is the first part of an investigation of caries-promoting and caries-inhibiting substances in commercial tobacco products. The total sugar content of pouch and plug forms of tobacco was, on the average, highest, followed by decreasing concentration in the pipe, cigarette, cigar, and snuff forms of tobacco. Fluoride content of the plug and pouch forms of tobacco was highest, followed by cigar, snuff, pipe, and cigarette tobacco, respectively. Generally, nonsmoking forms of tobacco are most directly related to the potential promotion of caries. The total sugar content in the control tobacco leaves was comparable to that in cigars and snuff which have the least amount of sugar, whereas the fluoride content was similar to plug and pouch which have the highest amount of fluoride. Brands of snuff on average had the lowest concentrations of sugar (average 1.9%) and were among the products with the lowest fluoride content (average 0.26 ppm). Pouch and plug exceeded other forms in both sugar and fluoride content. Large variations in sugar and fluoride levels of tobacco products can exist form-to-form, store-to-store, brand-to-brand, and state-to-state. This may explain the diverse opinions of dental practitioners and investigators relative to the concept that tobacco increases or decreases dental caries.

Calcium release after acid pretreatment of fluoridated and nonfluoridated enamel.

Spectrophotometric analysis of calcium released by the acid-etching procedure was used to evaluate the effect of topical fluoride on the acid resistivity of enamel. The influence of superficial enamel surface reduction (chamfering) on the efficacy of the etching procedure was investigated.