Regulation of periodontal ligament cell functions by interleukin-1beta

Periodontal ligament (PDL) cells maintain the attachment of the tooth to alveolar bone. These cells reside at a site in which they are challenged frequently by bacterial products and proinflammatory cytokines, such as interleukin-1beta (IL-1beta), during infections. In our initial studies we observed that IL-1beta down-regulates the osteoblast-like characteristics of PDL cells in vitro. Therefore, we examined the functional significance of the loss of the PDL cell's osteoblast-like characteristics during inflammation. In this report we show that, during inflammation, IL-1beta can modulate the phenotypic characteristics of PDL cells to a more functionally significant lipopolysaccharide (LPS)-responsive phenotype. In a healthy periodontium PDL cells exhibit an osteoblast-like phenotype and are unresponsive to gram-negative bacterial LPS. Treatment of PDL cells with IL-1beta inhibits the expression of their osteoblast-like characteristics, as assessed by the failure to express transforming growth factor beta1 (TGF-beta1) and proteins associated with mineralization, such as alkaline phosphatase and osteocalcin. As a consequence of this IL-1beta-induced phenotypic change, PDL cells become responsive to LPS and synthesize proinflammatory cytokines. The IL-1beta-induced phenotypic changes in PDL cells were transient, as removal of IL-1beta from PDL cell cultures resulted in reacquisition of their osteoblast-like characteristics and lack of LPS responsiveness. The IL-1beta-induced phenotypic changes occurred at concentrations that are frequently observed in tissue exudates during periodontal inflammation (0.05 to 5 ng/ml). The results suggest that, during inflammation in vivo, IL-1beta may modulate PDL cell functions, allowing PDL cells to participate directly in the disease process by assuming LPS responsiveness at the expense of their normal structural properties and functions.     

X-ray studies on crystalline complexes involving amino acids and peptides XXXIV. Novel mode of aggregation, interaction patterns and chiral effects in the maleic acid complexes of DL- and L- arginine

Amino acid - carboxylic acid complexes provide useful information in relation to molecular interactions in present day biological systems and to prebiotic self-organisation. The crystal structures of the complexes of maleic acid with DL- arginine (orthorhombic; Pca2(1); a=15.9829, b=5.4127, c=16.1885; R=0.0522 for 956 reflections) and L- arginine (triclinic; P1; a=5.2641, b=8.0388, c=9.7860, alpha=106.197, beta=97.275, gamma=101.64; R=0.039 for 1749 reflections) have been determined. The complexes are made up of positively charged zwitterionic arginine molecules and negatively charged semi-maleate ions which contain an intramolecular symmetric O-H-O hydrogen bond. In both the structures, the amino acid molecules aggregate into layers. In each layer, S2 head-to-tail sequences are interconnected through specific intermolecular interactions between alpha-carboxylate and guanidyl groups, an arrangement observed for the first time in crystal structures involving arginine. The carboxylate-guanidyl interactions are of different types in the two complexes and consequently aggregation patterns in them exhibit substantial differences. Interactions between the amino acid layers involve the semi-maleate ions in both the complexes. In addition, water-bridges also exist in the L complex. The full potential of the guanidyl group for specific interactions is realized in both the structures. The L complex contains an array of water-mediated salt bridges. The structures demonstrate that the effect of chirality on molecular aggregation can span a wide range.     

Laparoscopic splenectomy: outcome and efficacy in 103 consecutive patients

OBJECTIVE: To study the safety and efficacy of laparoscopic splenectomy (LS) in patients with predominantly benign hematologic disorders. SUMMARY BACKGROUND DATA: The technical feasibility of LS has been recently established. However, data regarding the efficacy of the procedure in a large cohort of patients are scarce. METHODS: One hundred three consecutive patients underwent LS between June 1992 and October 1997. Data were collected prospectively on all patients. RESULTS: Indications were idiopathic thrombocytopenic purpura (ITP), hereditary spherocytosis, autoimmune hemolytic anemia, thrombotic thrombocytopenic purpura, and others. Mean spleen size was 14 cm and mean weight was 263 g. Accessory spleens were found in 12 patients with ITP and in 5 patients without ITP. There were no deaths. Complications occurred in six patients, one requiring a second procedure for small bowel obstruction. Six patients received transfusions, and four procedures were converted to open splenectomy for bleeding. Mean surgical time was 161 minutes and was greater in the first 10 cases than the last 10. Mean postsurgical stay was 2.5 days. Thrombocytopenia resolved after surgery in 84% of patients with ITP, and hematocrit levels increased significantly in 70% of patients with chronic hemolytic anemias. A positive response was noted in 92% of patients with hereditary spherocytosis, without relapse for the duration of the observation. ITP relapsed in four patients during follow-up, three within 12 months. CONCLUSIONS: LS can be performed safely and effectively in a teaching institution. Rigorous technique will minimize capsular fractures, reducing the risk of splenosis. Accessory spleens can be successfully localized, thus improving response and limiting recurrence of ITP. LS should become the technique of choice for treatment of intractable benign hematologic disease.     

Liquefaction of coal by SRC-II process: Part V: Dynamic thermal behavior of the reactor

Criteria for identification of the unstable or stable nature of the steady state based on the reactor temperature response to step changes in feed temperature, and a dynamic thermal simulation of SRC-II reactors are developed. These are used in the analysis of a dynamic SRC-II reactor experiment to confirm its unstable operation under normal process conditions. The simulation is used further to study the sensitivity of reactor temperature to changes in feed temperature and to variations in the total heat capacity of the reactor vessel and insulation materials. It is shown that, under normal SRC-II process conditions, it would take about an hour for the reactor temperature to change by ± 10°C, if no controls were used. With quench gas manipulation, the reactor temperature could be maintained within ± 1°C even for a sustained small perturbation in the process conditions. Therefore, in spite of its unstable character, the SRC-II reactors can be readily operated with quench gas manipulation without incurring any major temperature control problems.     

Experimental studies of the force to extrude a rate sensitive material

Distinctions are drawn between three mean strain rates in extrusion: those averaged over the accumulated strain, the distance travelled through the die, and the elapsed time. It is shown that when the strain rate varies, the mean strain rate based on strain is always the greatest, and the mean strain rate based on time the smallest. Three further mean strain rates are introduced, which are root mean power (RMP) values of the above strain rates. Conventional estimates of the extrusion pressure for frictionless, homogeneous flow are based on rate insensitive analyses and lead to pressures proportional to the mean strain rate based on time. When the rate sensitivity during flow is taken into account, the calculated pressure is shown to be a function of the RMP strain rate based on accumulated strain, which is considerably greater than the mean strain rate based on time. Experiments are described in which ice was extruded by the indirect process, leading to nearly frictionless, homogeneous flow. Extrusion ratios of 4, 9, 25, 81, and 144 were used. In the first series of experiments, the ram velocity was adjusted to give the samerate insensitive (i.e. time-based) mean strain rate for all the dies. In the second series of experiments, the ram velocity was adjusted to give the samerate sensitive (i.e. RMP) mean strain rate for all the dies. In all cases the extrusion pressure was proportional to the RMP strain rate and not to the time-based strain rate. The rate sensitivity correction factor is also described.     

Stepwise Formation of Some Bivalent Metal Chelates with Sodium Alizarin Sulphonate

The stepwise protonation constants of the ligand and the stability constants of Alizarin Red S with some bivalent metal ions, Pb²⁺, Cu²⁺, Zn²⁺, and Hg²⁺ have been determined at 30° and at various ionic strengths viz. 0.02, 0.05, 0.15 and 0.20, maintained by sodium perchlorate solution. The formation of the chelate is evident from the shift between the (i) ligand and (ii) ligand and metal titration curves. From the values of the stepwise protonation constants and metal ligand stability constants at various ionic strengths, thermodynamic formation constants were evaluated by extrapolation to zero ionic strength. The order of stability constants was found to be: Cu > Pb > Zn > Hg     

Performance of piezoelectric fiber-reinforced composites for active structural-acoustic control of laminated composite plates

This paper deals with the active structural acoustic control of thin laminated composite plates using piezoelectric fiber-reinforced composite (PFRC) material for the constraining layer of active constrained layer damping (ACLD) treatment. A finite element model is developed for the laminated composite plates integrated with the patches of ACLD treatment to describe the coupled structural-acoustic behavior of the plates enclosing an acoustic cavity. The performance of the PFRC layers of the patches has been investigated for active control of sound radiated from thin symmetric and antisymmetric cross-ply and antisymmetric angle-ply laminated composite plates into the acoustic cavity. The significant effect of variation of piezoelectric fiber orientation in the PFRC layer on controlling the structure-borne sound radiated from thin laminated plates has been investigated to determine the fiber angle in the PFRC layer for which the structural-acoustic control authority of the patches becomes maximum.     

Microfluorometric detection of catecholamines with multiphoton-excited fluorescence

We demonstrate sensitive spatially resolved detection of physiological chromophores that emit in the ultraviolet (<330 nm). An atypical laser source (a visible wavelength femtosecond optical parametric oscillator), and an unconventional collection geometry (a lensless detector that detects the forward-emitted fluorescence) enable this detection. We report the excitation spectra of the catecholamines dopamine and norepinephrine, together with near-UV emitters serotonin and tryptophan, in the range of 550-595 nm. We estimate the molecular two-photon action cross section of dopamine, norepinephrine, and serotonin to be 1.2 mGM (1 GM, or Goppert Mayor, is equal to 10(-58) m4 s(-1) photon(-1)), 2 mGM, and 43 mGM, respectively, at 560 nm. The sensitivity achieved by this method holds promise for the microscopic imaging of vesicular catecholamines in live cells.     

Influence of thermophysical properties on pool boiling heat transfer of refrigerants

The correct prediction of the heat transfer performance of the boiling liquid within the evaporator of a refrigeration unit is one of the essential features for the successful operation of the whole unit. A theoretically consistent calculation method for the heat transfer coefficient α in nucleate boiling, which should be based on the physical phenomena connected with vapour bubbles growing, departing and sliding on the wall and with the interactions of bubbles and of neighbouring nucleation sites within the microstructure of the heating surface, does not yet exist, despite the increasing number of papers on the subject in the recent past. Instead, the predictive methods for α available at present are empirical or semiempirical, especially for heat transfer conditions relevant in practice. Many of these correlations have been established in the form of power laws in which the relative influences of the main groups of variables on α are treated by separate factors. One of these may stand for the influence of the thermophysical properties of the boiling liquid or these properties will be included in several of the factors.New experimental results are presented for pool boiling heat transfer from a single horizontal copper tube (8 mm OD) to HFC-refrigerants (R32, 125, 134a, 143a, 152a, 227ea) and hydrocarbons (propane, i-butane). The results are compared to experimental data from the literature, and methods are discussed, how to incorporate the data in semiempirical correlations to describe the influence of the thermophysical properties of the fluids on the heat transfer performance.