Induction of proliferation in isolated guinea pig gastric epithelium during restitution after superficial injury

Immediate repair of the gastrointestinal epithelium after superficial injury is called restitution. It is based on the migration of the surviving mucoid neck cells over the area of injury. The involvement of growth factors in the process has been recently documented. They are known to enhance the process (ie, EGF, FGF, TGF-beta) and to activate the basolateral Na+-H+-antiport (EGF). They may exert their effect by activating intracellular tyrosine kinases or by inducing chemotaxis. Yet, their precise mechanism of action in the process is unknown. The aim of the present study was to investigate the effect of modulation of the signal transduction pathway on the occurrence of proliferative mucoid neck and foveolar cells in guinea pig gastric epithelium. Therefore guinea pig gastric epithelium was mounted in Ussing chambers in vitro and perfused 4 hr after superficial injury with 1.25 M NaCl. The potential difference over the epithelium and tissue resistance were recorded simultaneously. The tissue was exposed either to cycloheximide, genistein, or to 4-phorbol myristate 13-acetate (PMA) during the 4-hr recovery, and the expression of proliferative cells was assessed by staining the tissue for proliferative cells (Ki-67). The mean proliferative index of tissues subjected to NaCl injury was significantly higher than that of uninjured control tissues after 4 hr of restitution. Inhibition of the signaling pathway with genistein decreased the proliferative index significantly, while its stimulation with phorbol myristate increased it. Both electrophysiologic and morphologic restitution were sensitive to genistein, but not to PMA or cycloheximide. Superficial epithelial injury results in a significantly increased occurrence of proliferative cells in isolated guinea pig gastric epithelium. This endogenous activation of the tissue is sensitive to inhibition by tyrosine kinases and to stimulation by protein kinases. Electrophysiologic and morphologic recovery are also affected by the modulation of the signaling pathway. This suggests that it is involved in the immediate repair process.     

Synthesis and characterization of conducting poly (1-aminonaphthalene), poly (2-aminonaphthalene) and poly (aniline-co-1-aminonaphthalene)

Poly (1&2)-aminonaphthalene and poly (aniline-co-1-aminonaphthalene) have been synthesized in high yields by chemical oxidative polymerization method. The polymers are soluble in polar solvents such as DMSO, NMP etc. In PNA-2 as head-to-tail coupling cannot occur, the electrical conductivity is lower than PNA-1. The copolymer exhibits distinct morphology, higher viscosity, characteristic exciton peak, appreciable thermal stability and electrical conductivity compared to PNA-1.     

Fuzzy-wavelet based prediction of Earth rotation parameters

Prediction of Earth rotation parameters (ERPs) is of importance especially for near real-time applications including navigation, remote sensing, and hazard monitoring. Therefore, prediction of ERPs at least over a few days in the future is necessary.Fuzzy-inference systems (FIS) are increasingly popular and have advantage over classical FFT that lacks stochastic stability due to non-stationarity, multiscaling, and persistent autocorrelations. Wavelet filtering can be used to handle such phenomenon. A FIS rule-base created from ERP time series, where the volatilities (returns) of the preprocessed series are used, and high frequency signals removed, is summarized. The performance of this system, trained using the fuzzy-wavelet method, is compared with that of a conventional FIS, trained on raw time series. The results show that the predictions by the fuzzy-wavelet method are superior to the FIS-only model for short-term predictions (up to 10 days in future). The improvement of prediction accuracy is found to be about 30% in terms of RMS error.     

Mechanisms of Load-Deformation Behavior of Molecular Collagen in Hydroxyapatite-Tropocollagen Molecular System: Steered Molecular Dynamics Study

Bone is a widely studied structure due to its important function in the human body and also for its unique mechanical properties, which depend upon several factors, such as, its hierarchal structure, its constituents, degree of interactions between different constituents, etc. The major constituents of bone are collagen and hydroxyapatite (HAP). In this work, the load-carrying behavior of collagen is evaluated using steered molecular dynamics simulations. It is observed that the mineral HAP influences the load-deformation behavior of collagen. The collagen molecule (tropocollagen) requires more energy to deform when it is in close proximity of HAP. The reasons for a typical load-deformation behavior are also analyzed. It is observed that with stretching of the tropocollagen, first hydrogen bonds between the tropocollagen chains break, as a result of which more water molecules start interacting with chains. HAP significantly alters the interaction between tropocollagen and water. The load-carrying behavior of tropocollagen at different loading rates is also analyzed by pulling collagen at different velocities. These simulations give important information about the molecular mechanics of collagen and are also useful for the development of novel biomimetic artificial implant materials.     

A study on the influence of Mo, Al and Si additions on the microstructure of annealed dual phase Cr–Ta alloys

The effects of additions of 5 at.% Mo, Al and Si on the long-term annealed microstructures of a two phase Cr–Cr₂Ta alloy have been studied. Following 200 h at 1300 °C, the lamellar eutectic constituent of all the alloys disintegrated into discrete particles of the Laves phase embedded within a Cr-rich solid solution phase, along with the formation of fine Laves phase precipitates. One of the predominant differences between the three alloying additions was the extent of the C14 to C15 polytypic transformation of the Cr₂Ta-based Laves phase. With Mo and Al additions, the Cr₂Ta Laves phase transformed from C14 to either C15 or intermediate hexagonal polytypes following 200 h annealing at 1300 °C. In contrast, Si additions stabilised the C14 polytype, with no transformation to other polytypes observed after prolonged annealing at 1000, 1100 and 1300 °C.     

Synthesis and characterization of poly(2,5-dimethoxyaniline) and poly(aniline-Co-2,5-dimethoxyaniline): The processable conducting polymers

Poly(2,5-dimethoxyaniline) (PDMOA) and its copolymers with aniline (PADMOA), which exhibit remarkably improved solubility in common organic solvents, were obtained by chemical polymerization, and characterized by a host of physical techniques. The lowering of the quinoid absorption in the IR spectra and the upshifting of the N_1s envelope in the XPS spectra indicate residual doping in the XPS polymers and thermal characteristic of the polymers provide evidence for hydrogen bonding, which appear to enhance the thermal stability of the homopolymer. These polymers are highly planar and conjugated, with well-developed polaronic features, shown by the XRD, ESR and UV-spectral data. The conductivity, however, is not high and apparently may be due to localization of polaronic charges at the hydrogen-bonding sites and the increased proportion of the insulating methoxy component in the polymer matrix.     

Poly(pyridinium salt)s with organic counterions derived from an aromatic diamine containing oxyethylene unit exhibiting amphotropic liquid-crystalline and photoluminescence properties

Several poly(pyridinium salt)s containing various organic counterions and oxyethylene unit in their backbones were synthesized by either the ring-transmutation polymerization reaction of 4,4′-(1,4-phenylene)bis(2,6-diphenylpyrylium tosylate) with 1,2-bis(4-aminophenoxy)ethane on heating in dimethyl sulfoxide or the metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by ¹H and ¹³C NMR spectroscopy, and elemental analyses. Their number-average molecular weights and polydispersity indices were in the range of 59,000-63,000 and 1.41-1.65, respectively, as determined by gel permeation chromatography. They were characterized for their thermotropic and lyotropic liquid-crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. Since these polymers exhibited liquid-crystalline phase both in the melt and in solutions, they belong to an amphotropic class of ionic polymers. Their light-emitting properties both in polar organic solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry.     

Primary spinal column sarcomas

Five cases of primary spinal column sarcomas are presented. Sarcomas primarily originating from paravertebral soft tissues were excluded. Patients' age ranged from 1 to 14 years (mean 8.4 years). The male:female ration was 2:3. Two patients had Ewing's sarcoma (ES) originating from L5-S1 and L4-5 pedicles, respectively; two patients had mesenchymal chondrosarcoma (MCS) originating from L1-2 pedicles and L5 body, respectively; and one patient had osteogenic sarcoma (OS) of C4 body. All patients clinically presented with pain and progressive weakness of the extremities. The time that elapsed between the onset of symptoms and diagnoses ranged from one to five months. All cases were treated with chemotherapy, radiotherapy and subtotal tumour resection with spinal canal decompression. Two cases received posterior spinal fusion operations. Three patients were alive 10 to 98 months following diagnosis. Only the case with ES of L5-S1 pedicles was in complete remission and off therapy at the 98th postoperative month. The two MCS cases were in partial remission, and were receiving chemotherapy at the time of analysis. These tumours caused similar clinical findings and prognoses, and required combined treatment, which consisted of surgery, radiotherapy and chemotherapy; histologically three different types of malignant tumours are presented in the same category. We preferred surgical decompression and stabilization procedures especially for neurologically symptomatic patients, even if they had extensive tumours with high grades. By spinal canal decompression and stabilisation, we did not intend to cure the disease; however, we intended to provide neurological improvement, spinal stabilisation, improved quality of life, early mobilisation of the patient, and cytoreduction by means of surgical tumour ablation, which could render the chemotherapy more effective.