Aldehydes, alcohols and acids were tested for their ability to support acetylene reduction and oxygen consumption by Rhizobium japonicum bacteroids isolated from soybean nodules. Several alcohols and aldehydes increased acetylene reduction and oxygen uptake. This is consistent with the concept that the plant nodule cytosol can metabolize carbohydrate via anaerobic fermentative pathways.
Although there is nearly equal distribution of results between all categories, a 35.7% rate of healing as assessed radiographically is essentially equivalent to the 38% failure rate. This paper will allow an evaluation of current research results to establish an outcome standard and enable techniques and filling materials to be evaluated and compared. Furthermore, the outcome standard can assist in defining demographic and aetiological factors that contribute to the potential outcome of resurgery cases.
(4,6,29). Control of pyruvate kinase activity is often exerted through ADP levels and activators like AMP and fructose 1,6-diP and inhibitors such as organic acids and ATP. Posttranslational modification (phosphorylation) may also be important (14). In gluconeogenic animal tissues, the enzyme is thought to be critical in regulating the flow of carbohydrates between the degradative glycolytic and synthetic gluconeogenic pathways (4,29). The same may be true for the plant enzyme (4). Regardless of whether gluconeogenesis is operative in the nodule, the availability of carbon skeletons and cofactors for ammonium assimilation could be influenced by pyruvate kinase activity. In addition, pyruvate kinases from the majority of plant and animal sources examined have been shown to have an absolute requirement for a monovalent cation for activity. Ammonium ion is a strong activator (10). As ammonia is the primary product of N2 fixation, and because of the presumed role of pyruvate kinase in regulation of carbohydrate metabolism, regulatory properties of the soybean nodule cytosol enzyme were examined. (8,21) was employed and reactions were terminated after 10 min. ADP and PEP concentrations were raised to 2.5 and 1.5 mm, respectively, for these assays. In both assays the reaction velocity was proportional to enzyme concentration over the range of concentrations used. Reactions were run at 30 C. In all cases, reaction mixtures without ADP were included in order to correct for PEP carboxylase activity. PEP carboxylase was assayed using a malate dehydrogenase enzyme couple. Assays contained 100 mm imidazole HCI (pH 7.5), 2 mm cyclohexylamine PEP, 5 mm MgCl2, 0; 16 mm NADH, 10 mm KHCO3, and 20 units of beef heart malate dehydrogenase. Coupled assays were performed with a Cary 11 or Carya 118 spectrophotometer. The Cary 118 was used for colorimetric assays and spectral studies. One unit of enzyme activity is defined as I ,umol of product/min at 30 C.Plant Extracts. All isolation steps were performed at 0 to 4 C. In a typical extraction, 18 g of nodules were extracted by grinding with 3 volumes of grinding medium and 6 g of insoluble PVP in a mortar and pestle. Grinding medium consisted of a 3:1 (v/v) mixture of buffer (100 mm imidazole-phosphate [pH 7.51 and 1.33 mM DTT)-glycerol. The extracts were filtered through four layers of cheesecloth and centrifuged 15 min at 37,000g. The supernatant was removed and 30 ml applied to a column (3 x 4 cm) of DEAEcellulose. The DEAE column was prepared by equilibrating with a 3:1 (v/v) mixture of buffer (10 mm imidazole-phosphate [pH 7.51 and 0.13 mm DTT)-glycerol (equilibrating medium). After addition of the enzyme, the column was washed with 2 column volumes of the equilibration medium, 0.075 M with respect to KCI. One column volume of equilibration medium, 0.175 M with respect to KCI, removed the single peak ofpyruvate kinase activity (7.5-10 units) from the column. Column flow rate during the entire procedure was 60 ml/hr. The specific activity of pyruvate kinase was increased 3.5-fo...
The benefits of a school-based plaque removal program are presented. Children in grades 5-8 were inclined in a study which was designed to determine the effect on oral hygiene, gingival inflammation and dental caries of removing dental plaque through supervised daily flossing and toothbrushing in school. A fluoride-free dentifrice was used. Controls did not receive instruction in plaque removal procedures nor did they engage in plaque removal activities at school. For three school years the students in the treatment group practiced daily plaque removal, supervised by trained personnel. All participants were examined initially for plaque (PHP), gingival inflammation (DHC) and dental caries (DMFS). Girls in the treatment group showed a significant reduction (28%) in mean plaque scores and, for girls and boys, the mean changes in gingivitis scores were significantly reduced (40% and 17%, respectively). Adjusted mean incremental DMF surface scores were 13% lower in the treatment group than in the control group. The difference between groups was not statistically significant and was accounted for entirely by the findings in mesial and distal surfaces (26%). This difference approached statistical significance (P=0.07).
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