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Salivary flow rate, immunoglobulin, and periodontal status were affected during a simulated Skylab mission. The effect is more prominent after long-duration space flights and can persist for several weeks after landing. The objective of this study was to determine the effect of a simulated Mars environment on periodontal status and levels of salivary microor-ganisms and immunoglobulins in the human oral cavity. Twelve healthy male volunteers were studied before, at 1 and 2 weeks, and after completion of a mission in an isolated, confined simulated Mars envi-ronment at the Mars Desert Research Station, USA. We conducted a current stress test, measured salivary immunoglobulin, Cortisol, α-amvlase, salivary flow rate, and levels of plaque and salivary microbes, and assessed clinical periodontal parameters (probing depth, bleeding on probing, and clinical loss of attach-ment). Salivary IgG levels and Streptococcus mutans activity were significantly higher at 1 week. Values for clinical periodontal parameters (probing depth, bleeding on probing, and clinical loss of attachment) significantly differed at 1 week. Stress might be caused by the difficulty of the mission rather than the isolated environment, as mission duration was quite short. Periodontal condition might worsen due to poor oral hygiene during the mission. The present findings show that all periodontal conditions and levels of oral bacteria and stress after completion of the simulated Mars mission differed from those at baseline. To verify the relationship between stress status and periodontal health in simulated Mars missions, future studies using larger patient samples and longer follow-up will be required. [ABSTRACT FROM AUTHOR]

Current projected missions to Mars will require 18 to 24 months of exposure to microgravity conditions, which might have serious effects on human physiology, including that of the oral cavity. Very few studies have been published on the effect of microgravity on the oral cavity, although it has been reported that microgravity increases the prevalence of periodontitis, dental caries, bone loss and fracture in the jaw bone, pain and numbness in teeth and oral cavity tissue, salivary duct stones, and oral cancer. Aeronautic dentistry is a new field, so further study of the effects of microgravity are required. In this article, we review the role of aeronautic dentistry in space missions and offer our recommendations for the future growth of this field. [ABSTRACT FROM AUTHOR]

Spaceflight occurs in an environment of temperature extremes, microgravity, solar and galactic cosmic radiation, lack of atmospheric pressure, and high-speed micrometeorites. Exposure to microgravity and the space environment during space missions of short and long duration has important medical and health implications for astronauts. Psychological well-being is of increasing importance in planned spaceflights and interplanetary missions of long duration. The 6° head-down tilt (HDT) is an established method of mimicking low gravity on earth. The aim of the present study was to determine the effects of 21 days of HDT on psychological stress in 12 healthy male volunteers. Psychological state was assessed by the current stress test, and chromogranin-A (CgA), cortisol, alpha-amylase, and beta-endorphin were measured in saliva. After one week of HDT, all volunteers developed psychological stress, and secretion of CgA, cortisol, alpha-amylase, and beta-endorphin were all significantly higher. Thus, 6° HDT appears to be a valid model to induce psychological stress changes in the immune system, changes that might also be encountered by astronauts and cosmonauts during both a short stay in space, such as that required while orbiting a space station, and in longer spaceflights. [ABSTRACT FROM AUTHOR]

In astronauts and cosmonauts, exposure to microgravity has been associated with several physiological changes, including an osteoporosislike loss of bone mass. It has been reported that head-down tilt bed-rest studies mimic many of the observations seen in space flights. There has been no study of the effects of mandibular bone and alveolar bone loss in both sexes under conditions of simulated microgravity. This study was designed to investigate bone mineral density; bone mineral content; matrix metalloproteinase (MMP)-8, MMP-9, cathepsin K, and osteocalcin levels in gingival crevicular fluid (GCF); and salivary and serum osteocalcin levels in normal healthy men and women under conditions of simulated microgravity, namely, -6° head-down-tilt (HDT) bed rest. The subjects of this investigation were 10 male and 10 female volunteers who were exposed to 3 weeks of -6° HDT bed rest. Dual-energy X-ray absorptiometry was used to measure bone density and bone mineral content in alveolar bone from the mandibular canine to the third molar, as well as in the mandibular ramus, before, during, and after exposure to conditions of simulated microgravity. GCF (ie, MMP-8, MMP-9, cathepsin K, and osteocalcin) and salivary and serum osteocalcin levels were measured by enzyme-linked immunosorbent assays. Bone mineral density and bone mineral content were significantly lower under conditions of simulated microgravity in both sexes. The decreases were greater in women than in men, but the differences between sexes were not significant. Cathepsin, osteocalcin, MMP-8, and MMP-9 levels were significantly higher under conditions of simulated microgravity than under normal conditions; the increases were greater in women than in men, but the differences were not significant. Additional, more comprehensive, studies with larger sample sizes are now necessary for the investigation of simulated microgravity and microgravity. [ABSTRACT FROM AUTHOR]

Extensive research within the past halfcentury has indicated that curcumin (diferuloylmethane), a yellow pigment in curry powder, exhibits anti-oxidant, anti-inflammatory, and proapoptotic activities. We investigated whether the antipre- cancer activities assigned to curcumin are mediated through an anti-oxidant and DNA-protecting mechanism. Patients with oral leukoplakia, oral submucous fibrosis or lichen planus, and healthy individuals (n = 25 for each group) aged 17-50 years were selected. Salivary and serum oxidative markers such as malonaldehyde (MDA), 8- hydroxydeoxyguanosine (8-OHdG), vitamins C and E were measured just prior to the intake of curcumin, after one week of curcumin intake and following clinical cure of precancerous lesions. Serum and salivary vitamins C and E showed increases, while MDA and 8-OHdG levels showed decreases in patients with oral leukoplakia, submucous fibrosis and lichen planus after intake of curcumin for all categories of precancerous lesions. The changes in these values were observed to be statistically significant after clinical cure of the disease (P < 0.05). The five-point rating scale for pain, as well as lesion size in oral leukoplakia, submucous fibrosis and lichen planus, improved significantly (P < 0.05). In addition, in submucous fibrosis, mouth opening (P < 0.05) recovered significantly. In oral leukoplakia, submucous fibrosis and lichen planus, the levels of serum and salivary vitamins C and E increased significantly, while MDA and 8-OHdG levels decreased after 131(15), 211(17), and 191(18) days, respectively. Values for serum and salivary vitamins C and E showed a significant decrease in oral leukoplakia, submucous fibrosis and lichen planus, in contrast to healthy individuals, but increased significantly in all groups subsequent to curcumin administration after clinical cure of lesions. Based on these results, we can conclude that curcumin mediates its anti-pre-cancer activities by increasing levels of vitamins C and E, and preventing lipid peroxidation and DNA damage. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinases (MMPs), the key enzymes responsible for matrix degradation, are derived from polymorphonuclear leukocytes during the early stages of periodontitis. The present study determined the levels of GCF matrix metalloproteinase-2 (MMP-2) and metalloproteinase-9 (MMP-9) and salivary MMP-8 in patients with gingivitis and periodontitis and in healthy controls. Levels of crevicular MMP-2, MMP-9 and salivary MMP-8 were determined by ELISA in subjects with healthy gingiva (n = 15), gingivitis (n = 18) and periodontitis (n = 20). Significantly higher salivary MMP-8 and crevicular MMP-9 were observed in cases of periodontitis compared to gingivitis and healthy adults. On the other hand, crevicular MMP-2 levels in periodontitis subjects were lower than those in gingivitis and healthy subjects. The three MMP levels were highly correlated to probing depth, and bleeding on probing. Salivary MMP-8, crevicular MMP- 2 and 9 may serve as biomarkers of periodontal disease and aid in early detection of periodontitis or gingivitis.