Non-tuberculosis mycobacteria in Africa. 3. Formamidase activity--its evaluation and practical application

The third study in a series on the prevalence of non-tuberculosis mycobacteria in Africa is devoted to the investigation of the formamidase activity of 288 cultures of mycobacteria, already typed by a battery of standard tests as pathogenic or atypical (184 strains) and saprophytic (104 strains). Of the latter, 96 (92.3%) were formamidase-positive, as compared with only 6 (3.3%) of the former. A close correlation was observed between the speed of growth on Löwenstein-Jensen medium and formamidase activity, 98 (96.1%) of the positive strains showing visible growth within 1-3 days. The relation between formamidase activity and growth on nutrient media was less clear-cut, however, and it was concluded that for the routine differentiation of saprophytic from other mycobacteria the formamidase test should be combined with simple tests such as speed of growth on L-J medium and ability to grow on nutrient media. Russel''s method and Nessler''s reagent for the detection of ammonia in the formamidase test were compared; the authors consider the former to be preferable, since the reaction is easier to read.     

Einfluß von L-Carnitin-supplementierter total parenteraler Ernährung (TPE) auf die postoperative Fett- und Stickstoff-Utilisation

Summary During episodes of trauma carnitine-free total parenteral nutrition (TPN) may result in a reduction of the total body carnitine pool, leading to a diminished rate of fat oxidation. Sixteen patients undergoing esophagectomy were equally and randomly divided and received isonitrogenous (0.2 gN/kg·day) and isocaloric (35 kcal/kg·day TPN over 11 days without and with L-carnitine supplementation (12 mg/kg·day). Compared with healthy controls, the total body carnitine pool was significantly reduced in both groups prior to the operation. Without supplementation carnitine concentrations were maintained, while daily provision of carnitine resulted in an elevation of total carnitine mainly due to an increase of the free fraction. Without supplementation the cumulative urinary carnitine losses were 11.5±6.3 mmol corresponding to 15.5%±8.5% of the estimated total body carnitine pool. Patients receiving carnitine revealed a positive carnitine balance in the immediate postoperative phase, 11.1%±19.0% of the infused carnitine being retained. After 11 days of treatment comparable values for respiratory quotient, plasma triglycerides, free fatty acids, ketone bodies, and cumulative nitrogen balance were observed. It is concluded that in the patient population studied here carnitine supplementation during postoperative TPN did not improve fat oxidation or nitrogen balance.

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Einfluß von L-Carnitin-supplementierter total parenteraler Ernährung (TPE) auf die postoperative Fett- und Stickstoff-Utilisation

Abkürzungsverzeichnis TPE total parenterale Ernährung=total parenteral nutrition - FC freies Carnitin=free carnitine - TASC gesamtes säurelösliches Carnitin=total acid soluble carnitine - LCC langkettiges Acylcarnitin=longchain carnitine - SCC kurzkettiges Acylcarnitin=shortchain carnitine - TC Gesamtcarnitin=total carnitine - AC Acylcarnitin=acyl carnitine - NCP nicht-kollagenes Protein=non-collagenous protein - RQ respiratorischer Quotient=respiratory quotient - np-RQ Nicht-Eiweiß-RQ=non-protein RQ     

A novel in vitro microbial-based model for studying caries formation--development and initial testing

We report on the development and the initial testing of a new microbial-based caries model. Specimens were fixed on a rotating mount within a reaction chamber hermetically surrounded by a sterilised glove box. A cariogenic environment was obtained by inoculation with Streptococcus mutans (ATCC 25175) combined with a continuously repeating supply of sucrose solution, trypticase soy broth and artificial saliva applied by dripping. Twenty-five caries-free upper premolars were used. The mesial parts of the occlusal fissures had been sealed with a resin-based fissure sealant (test group 1). To produce marginal gaps, the distal parts had been moistened with saliva before resin application (test group 2). Five teeth served as control and were exposed to all fluids under sterile conditions before being removed from the system after 7 days. Test specimens were infected with S. mutans and were incubated for another 14 days. No unintentional contamination occurred during the 3-week period of operation. Demineralizations were evaluated by using confocal laser scanning microscopy. Only the test specimens showed clearly visible signs of biofilm formation and caries-like lesions. The mean primary lesion depth did not differ significantly between test groups. Wall lesion depths and surface areas of demineralizations underneath the fissure sealants were significantly higher in test group 2. Thus, our model allows the simultaneous production of primary and secondary caries-like enamel lesions in a considerable number of specimens and facilitates the possibility to manipulate and transfer them without necessarily terminating the experiment, opening new possibilities for in vitro caries research.     

Caries-preventive potential of an adhesive patch after thermomechanical loading--a microbial-based in vitro study

PURPOSE: To assess the enamel-protective potential of a newly devised adhesive patch for smooth enamel sealing. MATERIALS AND METHODS: Approximal surfaces of 30 extracted molars were divided into three areas: the buccal thirds were treated with a flowable composite (Tetric Flow, Ivoclar Vivadent) and served as negative control sites, the lingual thirds were left untreated and served as positive control sites, and the middle thirds served as the test areas. This was sealed with either 1. a twofold application of an unfilled resin (Heliobond, Ivoclar Vivadent), 2. an adhesive prototype patch (Ivoclar Vivadent), or 3. an adhesive patch in combination with a flowable composite. After thermomechanical loading and demineralization in a microbial-based artificial caries chamber, demineralization depth was assessed using a confocal laser scanning microscope. RESULTS: Negative control sites treated with the flowable composite showed no signs of demineralization. Areas treated with the patch showed no signs of demineralization, irrespective of whether it was used in combination with a flowable composite or directly bonded to the enamel. Caries-like lesions in untreated sites showed a mean depth of 134.3 +/- 35.9 microm. Demineralization depth at sites treated with the unfilled resin was 76.2 +/- 26.5 microm (p = 0.023). CONCLUSIONS: Under the conditions of the present study, the adhesive patch under investigation completely protected the underlying enamel from demineralization. This merits further study to assess its potential as an interproximal sealant.     

Serologie. Blutgruppen. Bakteriologie und Immunitätslehre

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