Calmodulin-dependent regulation of inducible and neuronal nitric-oxide synthase

Neuronal and endothelial nitric-oxide synthases depend upon Ca2+/calmodulin for activation, whereas the activity of the inducible nitric-oxide synthase is Ca2+-independent, presumably due to tightly bound calmodulin. To study these different mechanisms, a series of chimeras derived from neuronal and inducible nitric- oxide synthases were analyzed. Chimeras containing only the oxygenase domain, calmodulin-binding region, or reductase domain of inducible nitric-oxide synthase did not confer significant Ca2+-independent activity. However, each chimera was more sensitive to Ca2+ than the neuronal isoform. The calmodulin-binding region of inducible nitric-oxide synthase with either its oxygenase or reductase domains resulted in significant, but not total, Ca2+-independent activity. Co-immunoprecipitation experiments showed no calmodulin associated with the former chimera in the absence of Ca2+. Trifluoperazine also inhibited this chimera in the absence of Ca2+. The combined interactions of calmodulin bound to inducible nitric-oxide synthase calmodulin-binding region with the oxygenase domain may be weaker than with the reductase domain. Thus, Ca2+-independent activity of inducible nitric-oxide synthase appears to result from the concerted interactions of calmodulin with both the oxygenase and reductase domains in addition to the canonical calmodulin-binding region. The neuronal isoform is not regulated by a unique autoinhibitory element in its reductase domain.     

Classification of black-pigmented anaerobes by pyrolysis mass spectrometry (PMS) and conventional tests (CTs)

Clinical (66: dental 53; vaginal 4; wound 9) and reference (5*) strains of pigmented Gram-negative anaerobic bacilli were examined in pyrolysis mass spectrometry (PMS) and conventional tests (CTs). The strains were identified in CTs as: Prevotella intermedia (48*); Pr. melaninogenica (1); Pr. corporis (7); Porphyromonas asaccharolytica (12*); P. endodontalis (1*) and P. gingivalis (2*). Numerical classification based on CTs resolved five clusters comprising strains identified as (I) Pr. corporis, (II) Pr. melaninogenica, (III) Pr. intermedia, (IV) P. gingivalis and (V) P. asaccharolytica and P. endodontalis. Numerical classification based on PMS showed a similar division, with decreasing homogeneity in the order Pr. intermedia, Pr. corporis, P. asaccharolytica, in agreement with the ordering of homogeneity for these species in CTs. PMS clusters corresponding the Porphyromonas spp. were clearly distinct from those of Prevotella spp. PMS and CT classifications disagreed on cluster membership for only six of the strains. PMS identification from blind challenge sets agreed with conventional identification for 64 of 67 strains.     

Disorders of temperature regulation

A remarkably effective and efficient thermoregulatory apparatus enables humans to maintain a normal body temperature despite widely varying and changing environmental and internal thermal conditions. Nevertheless, extreme ambient cold or heat and exhaustive exercise stress can overwhelm these defenses, leading to dangerous hypothermia or hyperthermia, respectively.     

Changes of telomere lengths in human intracranial tumours

The termini of human chromosomes comprise stretches of G-rich repeats that are about 5-20 kilobase (kb) in length. The size of the telomeres can be determined by hybridization with probes specific for these (ttaggg)n sequences after digestion of chromosomal DNA with appropriate restriction enzymes and electrophoretic separation of the fragments. Here, probing with the 32P-labelled synthetic (TTAGGG)3 oligonucleotide revealed length changes of the telomeres occurring in intracranial tumours. Among 60 samples, analysed, 41.7% showed telomere elongation, and 21.7% telomere reduction, whereas 36.7% of the tumours exhibited equal lengths compared with the patients' peripheral blood leukocytes. Most of the elongated glioma telomeres exceeded in length those of untransformed astrocytes derived from human fetal tissue.     

Primary respiratory failure as the presenting symptom in Lambert-Eaton myasthenic syndrome

Myasthenia gravis can present with rapid respiratory failure as the first manifestation of disease. In the Lambert-Eaton myasthenic syndrome (LEMS), such a manifestation has rarely been reported. We are reporting a patient who developed respiratory failure as the first manifestation of LEMS without associated carcinoma.     

Binding interaction of the heregulinbeta egf domain with ErbB3 and ErbB4 receptors assessed by alanine scanning mutagenesis

Individual residues of the heregulinbeta (HRG) egf domain were mutated to alanine and displayed monovalently on phagemid particles as gene III fusion proteins. Wild type HRGbeta egf domain displayed on phage was properly folded as evidenced by its ability to bind ErbB3 and ErbB4 receptor-IgG fusion proteins with affinities close to those measured for bacterially produced HRGbeta egf domain. Binding to ErbB3 and ErbB4 receptors was affected by mutation of residues throughout the egf domain; including the NH2 terminus (His2 and Leu3), the two beta-turns (Val15-Gly18 and Gly42-Gln46), and some discontinuous residues (including Leu3, Val4, Phe13, Val23, and Leu33) that form a patch on the major beta-sheet and the COOH-terminal region (Tyr48 and Met50-Phe53). Binding affinity was least changed by mutations throughout the Omega-loop and the second strand of the major beta-sheet. More mutants had greater affinity loss for ErbB3 compared with ErbB4 implying that it has more stringent binding requirements. Many residues important for HRG binding to its receptors correspond to critical residues for epidermal growth factor (EGF) and transforming growth factor alpha binding to the EGF receptor. Specificity may be determined in part by bulky groups that prevent binding to the unwanted receptor. All of the mutants tested were able to induce phosphorylation and mitogen-activated protein kinase activation through ErbB4 receptors and were able to modulate a transphosphorylation signal from ErbB3 to ErbB2 in MCF7 cells. An understanding of binding similarities and differences among the EGF family of ligands may facilitate the development of egf-like analogs with broad or narrow specificity.     

A mechanical comparison of subtrochanteric femur fracture fixation

The aim of this study was to compare in vitro diagnostic performance of three electrical methods for occlusal caries diagnosis with that of visual inspection and bite-wing radiography. One hundred and seven extracted molar and premolar teeth were subjected to the diagnostic methods by 2 operators and subsequently sectioned for histological validation. Electrical measurements were made at site level and at surface level using two different instruments. The diagnostic parameters calculated from the results were: sensitivity, specificity, diagnostic accuracy at a theoretical caries prevalence of 10% and area under the ROC curve. The electrical methods and bite-wing radiography showed higher sensitivity and lower specificity than visual inspection. Diagnostic accuracy was significantly lower for bite-wing radiography and one electrical method than for visual inspection. Overall diagnostic performance of two electrical methods was superior.     

SVD-based complexity reduction to TS fuzzy models

One of the typical important criteria to be considered in real-time control applications is the computational complexity of the controllers, observers, and models applied. In this paper, a singular value decomposition (SVD)-based complexity reduction technique is proposed for Takagi Sugeno (TS) fuzzy models. The main motivation is that the TS fuzzy model has exponentially growing computational complexity with the improvement of its approximation property through, as usually practiced, increasing the density of antecedent terms. The reduction technique proposed here is capable of defining the contribution of each local linear model included in the TS fuzzy model, which serves to remove the weakly contributing ones as according to a given threshold. Reducing the number of models leads directly to the computational complexity reduction. This work also includes a number of numerical and application examples     

Evaluation of a line probe assay kit for characterization of rpoB mutations in rifampin-resistant Mycobacterium tuberculosis isolates from New York City

A commercial line probe assay kit (Inno-LiPA Rif.TB) for rapid identification of mutations in the rpoB gene associated with rifampin resistance in Mycobacterium tuberculosis was evaluated with a collection of 51 rifampin-resistant strains. Nine distinct rpoB mutations were identified. Concordances with automated sequence results for five wild-type kit probes and four probes for specific mutations were 94.1 and 100%, respectively. Overall concordance of the line probe assay kit with phenotypic rifampin susceptibility testing results was 90.2%.