A 35 kDa NAD(P)H oxidase previously isolated from the archaeon Sulfolobus solfataricus is instead a thioredoxin reductase.

A thioredoxin reductase (TrxR) has been identified in the hyperthermophilic archaeon Sulfolobus solfataricus (Ss). This enzyme is a homodimeric flavoprotein that was previously identified as NADH oxidase in the same micro-organism ('Biotechnol. Appl. Biochem. 23 (1996) 47'). The primary structure of SsTrxR is made of 323 amino acid residues and contains two putative betaalphabeta regions for the binding of FAD, and a NADP(H) binding consensus sequence in the proximity of a CXXC motif. These findings indicate that SsTrxR is structurally related to the class II of the pyridine nucleotide-disulphide oxidoreductases family. Moreover, the enzyme exhibits a NADP(H) dependent thioredoxin reductase activity requiring the presence of FAD. Surprisingly, the reductase activity of SsTrxR is reduced in the presence of a specific inhibitor of mammalian TrxR. This finding demonstrates that the archaeal enzyme, although structurally related to eubacterial TrxR, is functionally closer to eukaryal enzymes. Experimental evidences indicate that a disulphide bridge is required for the reductase but also for the NADH oxidase activity of the enzyme. These results are further supported by the significantly reduced activities exerted by the C147A mutant. The integrity of the CXXC motif is also involved in the stability of the enzyme.

Flexural wave propagation velocity and bone mineral density in females with and without tibial bone stress injuries.

STUDY DESIGN: Case-control nonexperimental design. OBJECTIVES: To compare flexural wave propagation velocity (FWPV) and tibial bone mineral density (BMD) in women with and without tibial bone stress injuries (BSIs). BACKGROUND: Physical therapists, particularly in military and sports medicine settings, routinely diagnose and manage stress fractures or bone stress injuries. Improved methods of preparticipation quantification of tibial strength may provide markers of BSI risk and thus potentially reduce morbidity. METHODS AND MEASURES: Bone mineral density, FWPV, bone geometry, and historical variables were collected from 14 subjects diagnosed with tibial BSIs and 14 age-matched controls; all 28 were undergoing military training. RESULTS: No difference was found between groups in FWPV and tibial BMD when analyzed with t tests (post hoc power = 0.89 and 0.81, respectively). Furthermore, no difference was found in tibial length, tibial width, femoral neck BMD, and lumbar spine BMD among the groups. There were no differences between the 2 groups in smoking history, birth control pill use, and onset of menarche. Finally, sensitivity and positive likelihood ratios for FWPV (0.14 and 0.63), tibial BMD (0.0 and 0.0), and lumbar BMD (0.18 and 2.0) were low, while specificity was high (0.77, 0.93, and 0.91, respectively). CONCLUSION: Current bone analysis devices and methods may not be sensitive enough to detect differences in tibial material and structure; local stresses on bone may be more important in the development of BSIs than the overall structural stiffness.

A NAD(P)H oxidase isolated from the archaeon Sulfolobus solfataricus is not homologous with another NADH oxidase present in the same microorganism. Biochemical characterization of the enzyme and cloning of the encoding gene.

A NAD(P)H oxidase has been isolated from the archaeon Sulfolobus solfataricus. The enzyme is a homodimer with M(r) 38,000 per subunit (SsNOX38) containing 1 FAD molecule/subunit. It oxidizes NADH and, less efficiently, NADPH with the formation of hydrogen peroxide. The enzyme was resistant against chemical and physical denaturating agents. The temperature for its half-denaturation was 93 and 75 degrees C in the absence or presence, respectively, of 8 M urea. The enzyme did not show any reductase activity. The SsNOX38 encoding gene was cloned and sequenced. It accounted for a product of 36.5 kDa. The translated amino acid sequence was made of 332 residues containing two putative betaalphabeta-fold regions, typical of NAD- and FAD-binding proteins. The primary structure of SsNOX38 did not show any homology with the N-terminal amino acid sequence of a NADH oxidase previously isolated from S. solfataricus (SsNOX35) (Masullo, M., Raimo, G., Dello Russo, A., Bocchini, V. and Bannister, J. V. (1996) Biotechnol. Appl. Biochem. 23, 47-54). Conversely, it showed 40% sequence identity with a putative thioredoxin reductase from Bacillus subtilis, but it did not contain cysteines, which are essential for the activity of the reductase.

Reliability of water volumetry and the figure of eight method on subjects with ankle joint swelling.

STUDY DESIGN: Single-group repeated measures with 2 raters. OBJECTIVES: To determine the interrater and intrarater reliability of water volumetry and the figure of eight method on subjects with ankle joint swelling. BACKGROUND: Measurements of ankle swelling are commonly performed to determine the nature and stage of injury and to monitor progress made during rehabilitation. Water volumetry and the figure of eight method are 2 techniques used to measure ankle swelling. METHODS AND MEASURES: Twenty-nine subjects with ankle swelling were measured by 2 raters with the hypothesis that both measurement techniques would be reliable. Each rater performed 3 measurements of the swollen ankle using both measurement techniques during a single test session. The order of the rater and of the measurement technique was randomized, and the raters were blinded to each other's measurements. RESULTS: We found high interrater reliability for both the water volumetry (ICC [intraclass correlation coefficient] = 0.99) and figure of eight methods (ICC = 0.98). Additionally, intrarater reliability was high for both raters using both methods (ICCs = 0.98-0.99). CONCLUSIONS: Both methods are reliable measures of ankle swelling. The authors recommend the figure of eight method because of its ease of use, time efficiency, and cost effectiveness. However, water volumetry may be more appropriate when measuring diffuse lower-extremity swelling. Reliability of these 2 methods was established using subjects with foot or ankle pathology. Therefore, the results are applicable and generalizable to the clinical setting.

[Ventricular tachycardia]. / La tachicardia ventricolare.

Various electrocardiographic forms of ventricular tachycardia are described. After a discussion of the different pathogenetic mechanisms about this arrhythmia, the various types of pharmacological and electrical treatment are examined.