Properties of hexokinase bound to glass.
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Biomedical subjects
Publications and source records attributed to J Shapira.
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Multiple studies directed toward the development of a regenerative life support system have shown that easily synthesized organic compounds and microbiological materials are potentially capable of being used as foods for long-duration space missions. Animal feeding studies have supported these views. The organic compounds presently believed to offer the greatest potential are glycerol, simple glycerol derivatives such as triacetin, and formose sugars. Laboratory studies indicate that glycerol can be synthesized from formaldehyde which in turn is obtained by the direct catalytic oxidation of methane, a by-product of the Sabatier reaction used in spacecraft atmosphere control system. Formose sugars are derived from the self-condensation of formaldehyde. Mixtures of glycerol and triacetin have been shown to be suitable as a major component of diets fed to weanling rats for prolonged periods. These compounds do not exist as stereoisomers and therefore offer advantages over the formose sugars. Hydrogenomonas eutropha is the microbiological system under investigation. An automated system for the continuous autotrophic production of Hydrogenomonas bacteria is in operation, and the nutritional requirements for growth in the system using urea as a nitrogen source are being studied. Nutritional evaluation of Hydrogenomonas bacteria has shown they are capable of supplying the total protein requirement of growing rats for prolonged periods. The potential and problems of these regenerative systems and the prospects for the accomplishment of a totally regenerative food system will be discussed.
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Behavior of patients with autistic syndrome makes delivery of oral hygiene and dental treatment a problem. In this study, the oral health and needs of two groups of patients with autism were evaluated: noninstitutionalized children with a mean age of 11 and institutionalized adults with a mean age of 22. The latter group had severe periodontal problems; almost half required periodontal surgery. Many of the children also needed periodontal treatment. Adults were found to have lower decayed, missing, and filled teeth (DMFT) scores than functionally independent Israeli persons of the same age. This finding was surprising because institutionalized adults are predisposed to development of dental caries; they frequently consume sweets, have poor oral hygiene, and do not use fluoride. Noninstitutionalized children with autism had caries rates that were similar to rates of functionally independent peers.
The prevalence of dental caries and periodontal treatment needs in an institutionalized Down syndrome (DS) population was examined as well as the relationship between caries prevalence, salivary pH and salivary levels of Streptococcus mutans. Twelve patients with DS, aged 20 to 48, were compared with two similar age and gender control groups: healthy, and non-Down institutionalized mentally retarded patients. The pH levels did not differ significantly among the three groups. As to periodontal needs expressed by the CPITN, the institutionalized groups had the highest needs compared with the healthy group. Down adults, who were cariesfree, had significantly lower S. mutans counts compared with the patients with caries. In addition, the cariesfree patients with DS had much lower CPITN scores compared with the patients with caries.
The prevalence of dental caries and periodontal treatment needs in an institutionalized population with Down syndrome was examined and the relationship between caries prevalence, salivary pH, and salivary levels of Streptococcus mutans was studied. Thirty-two children with Down syndrome, aged 8 to 13, were compared with two control groups of similar age ranges: healthy children and non-Down mentally retarded (MR) children living in the same institution as the Down syndrome population. The gender ratio mixtures in each group also matched the study sample. Caries experience as indicated by decayed, missing, and filled surfaces (DMF-S) showed significantly lower mean scores for the Down syndrome group compared with both control groups. A similar pattern was found when evaluating the mean numbers of decayed surfaces. Streptococcus mutans counts, expressed as number of colony-forming units on mitis salivarius agar plates among the Down syndrome group, were the lowest, although not statistically significant compared with the counts of the healthy children. Both groups had bacterial counts which were significantly lower than those of the MR group. Significant differences between the two institutionalized groups and the healthy group were recorded for the salivary pH levels. The periodontal treatment needs as evaluated by the Community Periodontal Index of Treatment Needs showed significant difference between the MR group versus both the healthy population and the Down syndrome group. On the whole, 84% of the Down syndrome children were cariesfree.
Local applications of sustained-released varnishes of chlorhexidine and arginine were used in a controlled pilot study of 34 mentally retarded patients, ages 18-45, assigned to one of these groups: chlorhexidine (C), arginine (A), or placebo (P). A professional scaling followed by four weeks of professional brushing to reach a Plaque Index (PII) and Gingival Index (GI) of 1.0 at baseline preceded eight weeks of daily varnish application to the buccal and labial surfaces of all teeth. Clinical parameters (PII and GI) and bacterial samples from selected teeth were collected at predetermined intervals. Four and eight weeks following the baseline, the PII was significantly different among the groups, with the lowest score in the chlorhexidine group. No significant differences among the three groups were noted for the GI. The chlorhexidine and arginine groups showed significant reductions (p < 0.05 and p < 0.01, respectively) in the number of S. mutans. The arginine group showed a nonsignificant increase in the number of S. sanguis. These results suggest that the topical antimicrobial agents may have some relevance to plaque control among patients with mental retardation.
A comprehensive systematic preventive dental health program was implemented in a young population with Down's Syndrome during a 30-month period. Twenty children (nine boys and 11 girls), ages 8-13 (mean age, 11), participated in the study, which took place in three hostel-like apartments. The main goals of this program were to achieve good plaque control and subsequently prevent periodontal disease as well as to apply fissure sealants and fluorides in an attempt to prevent dental caries. The mean plaque and gingival indices as well as the percentage of bleeding sites decreased significantly (P < 0.01) following the administration of our oral health program. Caries experience, as indicated by DMFS, decreased from 1-35 to 1-05 surfaces per child, and the use of fissure sealants to prevent occlusal caries was proved to be 100% effective. It is concluded that if the children's efforts are integrated with those of a motivated dentist, dental hygienist, and staff, a well-planned preventive dental health program can lead to a high degree of success in the prevention of dental diseases in young populations with Down's Syndrome.
The dental status and treatment needs of Israeli children and adults with mental retardation were studied in a random sample of 387 subjects. Four levels of mental retardation were represented: (1) educable (n = 70), (2) trainable (n = 92), (3) with mental retardation and behavioral problems (n = 106), and (4) with mental retardation and severe physical handicap (n = 119). The total age-adjusted DMF-T was 12.78 and differed significantly by behavioral group (p < 0.001); the M-T was 10.70 for the educable group compared with 5.52 for the group with mental retardation and severe physical handicap. Total treatment needs included a participant mean of 3.32 for restorations and 0.61 for extractions. Institutions having dental clinics had higher participant mean DMF-T, D-T, M-T, and F-T values (p < 0.05) compared with those institutions which had no clinics (16.04 vs. 9.74; 5.17 vs. 5.06; 9.45 vs. 4.16; 1.41 vs. 0.52). Age-adjusted CPITN scores significantly differed by behavioral group; the group with mental retardation and severe physical handicap had the highest CPITN 3 category mean score of 2.93 compared with x = 1.89 for the educable group; however, the educable group had the most sextants with no teeth (x = 2.48). Findings confirm high dental morbidity and significant oral health differences by behavior group, age, and dental clinic status. Advanced training is recommended for dental providers and the staffs of institutions to enhance oral health outcomes.