Free amino acids in human palatine gland secretions

Human palatine gland saliva (HPS) was collected from young adult subjects (mean age 22 yr) of both sexes by gentle mechanical stimulation. The HPS contained 9-13 of the common amino acids within the range of 2--850 nmol/ml, but most samples had low or no concentrations of arginine, tryptophan and proline. Methionine and cysteine were not reliably detected. The molar ratios of most amino acids varied between subjects, but the ratio of leucine to isoleucine was remarkably constant (mean +/- SD = 1.86 +/- 0.28; N = 28). The minimum average secretion rate of HPS, using gentle mechanical stimulation, was estimated to be about 25 mg/min (wet weight).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27596/1/0000640.pd

Collagenolytic and phosphatase activity in the rat mandible after functional protrusion

The effect of chronic mandibular protrusion on the collagenolytic and phosphatase activity of several mandibular bone sites and the condylar cartilage was evaluated. Ninety-three male Sprague-Dawley rats were equally divided into two experimental and one control group. One experimental group wore a protrusive appliance for 2 weeks, the other for 4 weeks. All animals were killed at 59 days of age. Collagenolytic, alkaline and acid phosphatase activities were determined in the condylar cartilage, the subchondral bone and condylar neck, and in the gonial angle and coronoid process. In the cartilage and subchondral bone, the protrusive appliance caused a reduction in collagenolytic and alkaline phosphatase activity. In the condylar neck, it caused a large increase in collagenolytic activity and a decrease in alkaline phosphatase activity in both experimental groups. In the gonial angle and coronoid process, the appliance increased the collagenolytic activity only in the 2-week group. In the 4-week group, the alkaline phosphatase and collagenolytic activities were not different from the activities in those tissues in the control animals. Thus a protrusive appliance induced quantitative changes in enzyme activities in condylar cartilage and mandibular bone. The increase in collagenolytic activity (representing increased bone resorption) occurred typically in areas of muscle attachment and might have been the result of the neuromuscular changes induced by the protrusive appliance. The recovery to normal values of collagenolytic activity in the coronoid process and gonial angle of the 4-week group suggests that at these sites the muscles (and subperiosteal bone) might have adapted to their new biomechanical environment after the longer period of appliance wear.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28165/1/0000617.pd

Xylitol Chewing Gums and Caries Rates: A 40-month Cohort Study

Dental caries is a pandemic infectious disease which can affect the quality of life and consumes considerable health care resources. The chewing of xylitol, sorbitol, and even sugar gum has been suggested to reduce caries rates. No clinical study has simultaneously investigated the effectiveness of these gums when compared with a group receiving no chewing gum. A 40-month double-blind cohort study on the relationship between the use of chewing gum and dental caries was performed in 1989-1993 in Belize, Central America. One thousand two hundred and seventy-seven subjects (mean age, 10.2 years) were assigned to nine treatment groups: one control group (no supervised gum use), four xylitol groups (range of supervised xylitol consumption: 4.3 to 9.0 g/day), two xylitol-sorbitol groups (range of supervised consumption of total polyols: 8.0 to 9.7 g/day), one sorbitol group (supervised consumption: 9.0 g/day), and one sucrose group (9.0 g/day). The gum use during school hours was supervised. Four calibrated dentists performed the caries registrations by means of a modified WHO procedure. The primary endpoint was the development of an unequivocal caries lesion on a non-cavitated tooth surface. Compared with the no-gum group, sucrose gum usage resulted in a marginal increase in the caries rate (relative risk, 1.20; 95% confidence interval, 0.96 to 1.49; p = 0.1128). Sorbitol gum significantly reduced caries rates (relative risk, 0.74; 95% confidence interval, 0.6 to 0.92; p = 0.0074). The four xylitol gums were most effective in reducing caries rates, the most effective agent being a 100% xylitol pellet gum (relative risk, 0.27; 95% confidence interval, 0.20 to 0.36; p = 0.0001). This gum was superior to any other gum (p < 0.01). The xylitol-sorbitol mixtures were less effective than xylitol, but they still reduced caries rates significantly compared with the no-gum group. DMFS analyses were consistent with these conclusions. The results suggest that systematic usage of polyol-based chewing gums reduces caries rates in young subjects, with xylitol gums being more effective than sorbitol gums.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68231/2/10.1177_00220345950740121501.pd

Near stoichiometric, irreversible inactivation of bacterial collagenases by o-chloranil (3,4,5,6-tetrachloro-1,2-benzoquinone)

SummaryThe hydrogen-abstracting quinone derivative 3,4,5,6-tetrachloro-1,2-benzoquinone (o-chloranil) caused a strong, near stoichiometric, irreversible inactivation of the collagenases from Bacillus cereus, Clostridium histolyticum and Achromobacter iophagus. p-Chloranil was a weaker inactivator. o-Chloranil reacted rapidly with a site that affected substrate binding. Amino acid analyses of native and totally inactivated enzymes, and the pH-profile of inactivation suggest that the dissociated form of a tyrosine residue was modified.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27289/1/0000308.pd