Search

Objectives Osteoradionecrosis (ORN) is a complication of head and neck radiation therapy (RT) and is associated with significant morbidity. The incidence of ORN is variable, and it has been speculated to be lower with advanced RT techniques. Risk factors that have been associated with the development of ORN mainly include trauma and a radiation dose to the head and neck region greater than 60 Gy. However, in a study conducted by our group, ORN developed spontaneously (without any known history of trauma or dentoalveolar procedure) in 82% of the ORN cohort following intensity-modulated radiation therapy (IMRT).The purpose of this study was to characterize spontaneous ORN and to compare spontaneous ORN with nonspontaneous ORN (e.g., related to trauma or dentoalveolar procedures). Study Design Following approval by the Institutional Review Board of the Memorial Sloan Kettering Cancer Center (MSKCC), the treatment records of 44 patients with spontaneous ORN (group A) and 24 patients with nonspontaneous ORN (group B) treated with IMRT at the MSKCC for head and neck cancer (HNCa) were identified and retrospectively reviewed. Average prescribed mean and maximum radiation doses for the region of ORN were calculated by using MSKCC's proprietary radiation treatment planning software. Furthermore, Fischer's exact test was used to compare patient characteristics, such as primary site, tumor stage, smoking status, and other comorbidities, between the spontaneous ORN group and the nonspontaneous ORN group. Results According to preliminary data from 12 patients in group A and 6 patients from group B, the patients in group A appeared to have been exposed to higher radiation doses (Dmax; greater than 70 Gy) compared with group B. Furthermore, no statistical significance was noted between the 2 groups with regard to primary tumor, tumor stage, smoking status, and comorbidities, such as cardiovascular disease and hypertension (P > .05). However, statistical significance was evident for diabetes in group B (P Conclusions Collection of data on the expanded cohort of patients from each group, as well as other variables, such as radiation therapy fractionation, is ongoing. Our initial data indicates that increased radiation dose greater than 70 Gy may be associated with the development of spontaneous ORN.

Aims Paraquat (PQ) is known to induce pulmonary injury via a redox cyclic reaction. The present study was aimed to determine the protective effects of quercetin against PQ-induced pulmonary injury in association with its antioxidant activity. Main methods Male rats were challenged acutely by PQ (50 mg/kg, i.p.) with or without quercetin post-treatment. Pulmonary heme oxygenase-1 (HO-1) expression, malondialdehyde (MDA) level, and the total oxyradical scavenging capacity (TOSC) toward hydroxyl, peroxyl radicals and peroxynitrite were measured 24 h after PQ treatment. Different groups of rats were instilled with PQ (0.5 mg/kg) directly into the right lung. Quercetin was administered to the rats daily for 14 days after PQ instillation. Serum NO, pulmonary glutathione (GSH) and 4-hydroxyproline (4-HP) concentrations were quantified in conjunction with histopathological examination to determine the fibrotic changes in lung. Key findings Pulmonary MDA level and HO-1 expression were elevated and the TOSC was reduced rapidly by an intraperitoneal dose of PQ. These changes were inhibited by quercetin post-treatment. In rat lungs instilled with PQ 14 days before, NO, MDA and 4-HP were elevated, and GSH was reduced, which were all inhibited significantly by daily quercetin treatment. Histopathological examination also revealed that quercetin ameliorated the increase in fibroblast distribution and collagen deposition in the lungs instilled with PQ. Significance The present results demonstrate that quercetin administration to rats effectively inhibits the development of PQ-induced pulmonary injury most probably via its antioxidant activity.

We described a simple route to TiO 2 nanoparticles with anatase phase by the acid-catalyzed sol–gel process of titanium(IV) bis(acetylacetonate) diisopropoxide in water, and studied the effect of chelation of the precursor on the crystallite and size of anatase TiO 2 . The nanocrystalline anatase TiO 2 was obtained by controlling pH of aqueous solution containing the precursor at temperatures as low as room temperature. The ligands of the precursor complex were characterized by FT-IR and UV–vis spectroscopy. The sustenance of chelation of the precursor in an acidic solution may be a key factor to determine the crystalline phase of TiO 2 at such mild conditions.

Thin films of the conducting polymer poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) were deposited by resonant infrared laser vapor deposition (RIR-LVD). The PEDOT:PSS was frozen in various matrix solutions and deposited using a tunable, mid-infrared free-electron laser (FEL). The films so produced exhibited morphologies and conductivities that were highly dependent on the solvent matrix and laser irradiation wavelength used. When deposited from a native solution (1.3% by weight in water), as in matrix-assisted pulsed laser evaporation (MAPLE), films were rough and electrically insulating. When the matrix included other organic “co-matrices” that were doped into the solution prior to freezing, however, the resulting films were smooth and exhibited good electrical conductivity (0.2 S/cm), but only when irradiated at certain wavelengths. These results highlight the importance of the matrix/solute and matrix/laser interactions in the ablation process.

As a promising solution to tackle the network heterogeneity in multicasting, layered multicast protocols such as receiver-driven layered multicast (RLM) and layered video multicast with retransmission (LVMR) have been proposed. This paper considers fairness as well as transmission load in the layered multicasting. Lexicographically fair bandwidth allocation among multicast receivers is considered under the constraint of minimum bandwidth requirement and the link capacity of the network. The problem of transmission load in the layer multicasting due to various user requirements is also examined by minimizing the number of layers. The bandwidth allocation is formulated as a nonlinear integer programming problem. A dual-objective tabu search is proposed to solve the fairness and transmission load problem in multicast networks. Outstanding performance is obtained by the proposed tabu search. When the fairness objective is considered, the solution gap from the optimal solution is less than 2% in problems with 50 virtual sessions. The complexity of the dual objective largely depends on the weighting factor of the two objectives. Even in tough cases the proposed tabu search provides excellent solution, whose gap is within 6% from the optimal solution.

Background context Recent literature has raised some apprehensions with regard to the usage of cervical cages. Purpose Radiological review of cases performed at our institution with a novel cage made of polyetheretherketone (PEEK). Study design Retrospective study. Methods A retrospective review of the first 15 consecutive cases of single-level anterior cervical interbody fusion using the Solis cage (PEEK material) for cervical spondylotic radiculopathy or myelopathy was performed. The follow-up ranged from 12 to 35 months (average 18 months). Anteroposterior and lateral radiographs were taken immediately after the surgery and at intervals of 3, 6, 12, and 24 months after surgery. Anterior disc height (ADH), posterior disc height (PDH), interbody height ratio (IBHR), distance between the posterior margin of the cage and the posterior wall of the vertebral body (D-CPW), and interbody angle (IBA) were measured on the lateral radiographs and compared. Fusion was assessed by examining for trabecular continuity, bridging of bone across the disc space, and sclerosis at the vertebral end plates on both sides. The parameters assessed were time for fusion, subsidence, segmental sagittal alignment of the operated segment, and presence/absence of migration of the cage. Data were analyzed using the Mann-Whitney nonparametric test. Results Fusion was evident at 3–6 months postsurgery in all cases except one (93.33% fusion rate at 6 months). At the last follow-up, fusion was maintained in all cases. The immediate postoperative ADH and PDH was significantly greater than the respective preoperative values and was maintained at the last follow-up though there was a significant amount of subsidence when the follow-up radiographs were compared with the immediate postoperative X-rays. The immediate postoperative IBHR was significantly greater than the preoperative IBHR, and was maintained at the last follow-up, but not statistically significant. The immediate postoperative IBA (lordotic angle) was greater than the preoperative IBA but was not statistically significant. The IBA at the last follow-up was lesser than the preoperative value but with no statistical significance. The IBA measured at the last follow-up was less than the value at the immediate postoperative period, but not statistically significant. There was no migration or extrusion of the cage at latest follow-up. Conclusions The high fusion rate, low subsidence, stability provided by the cage, and facilitation of radiological assessment are the result of the physical properties of the PEEK material as well as the design of the cage.

Overlay multicast makes use of the Internet as a low level infrastructure to provide multicast service to end hosts. The strategy of overlay multicast slides over most of the basic deployment issues associated with IP multicast, such as end-to-end reliability, flow and congestion control, and assignment of an unique address for each multicasting group. Since each multicast member is responsible for forwarding multicast packets, overlay multicast protocols suffer from multicast node failures. To cope with node failures in the overlay multicast networks, the employment of multicast service nodes (MSNs) is considered which allows relatively high processing performance to cover the disconnected nodes. We are interested in minimizing the cost of both the MSNs and additional links when a node failure occurs. Overlay multicast tree rearrangement to connect multicast members is discussed and formulated as a binary integer programming problem. The tree rearrangement problem is solved by a heuristic based on the Lagrangian relaxation. The performance of the proposed algorithm is investigated by carrying out experiments in 50 and 100 node problems. The employment of MSNs is illustrated to be dependent on the end-to-end delay bound in overlay networks and the degree constraint of member nodes.

The multicasting is defined as the distribution of the same information stream from one to many nodes concurrently. There has been an intensive research effort to design protocols and construct multicast routing graphs for a single multicast group. In this paper, the multiple multicast tree allocation problem is discussed and algorithms are proposed to solve the congestion problem in the IP network. As the congestion measure the minimum residual capacity is considered. Two phase algorithm MMTA is investigated for multiple multicast tree allocation both for identical and different bandwidth requirement by the multicast groups. The central and distributed implementation of the multiple multicast tree is discussed for the deployment in the real IP network. The performance of the proposed MMTA is compared with other procedures. Computational results show that the two-phase MMTA outperforms other procedures. Approximately 3-7% improvement in the residual capacity is obtained by the MMTA. The solution gap from the upper bound by the well-known branch and bound is within 2-11% depending on the problem size.

With the increase of internet protocol (IP) packets the performance of routers became an important issue in internet/working. In this paper we examine the matching algorithm in gigabit router which has input queue with virtual output queueing. Dynamic queue scheduling is also proposed to reduce the packet delay and packet loss probability. Port partitioning is employed to reduce the computational burden of the scheduler in a switch which matches the input and output ports for fast packet switching. Each port is divided into two groups such that the matching algorithm is implemented within each pair of groups in parallel. The matching is performed by exchanging the pair of groups at every time slot. Two algorithms, maximal weight matching by port partitioning (MPP) and modified maximal weight matching by port partitioning (MMPP) are presented. In dynamic queue scheduling, a popup decision rule for each delay critical packet is made to reduce both the delay of the delay critical packet and the loss probability of loss critical packet. Computational results show that MMPP has the lowest delay and requires the least buffer size. The throughput is illustrated to be linear to the packet arrival rate, which can be achieved under highly efficient matching algorithm. The dynamic queue scheduling is illustrated to be highly effective when the occupancy of the input buffer is relatively high.

Microwave spectra of the three Group 13 metal cyanide pairs AlNC/AlCN, GaNC/GaCN, and InNC/InCN have been measured in the frequency range 6–25 GHz using a pulsed jet cavity Fourier transform microwave spectrometer. The molecules were prepared by ablating the metal with a pulsed Nd:YAG laser and allowing the vapor to react with cyanogen or acetonitrile contained in the Ar backing gas of the jet. The spectra are those of linear molecules. Rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling constants have been precisely evaluated. Molecular geometries determined from the rotational constants using a linear model have revealed unexpectedly short NC bond lengths for the isocyanides, MNC, and are interpreted in terms of a broadened potential well for the bending mode of these molecules. This interpretation is confirmed with ab initio calculations. The centrifugal distortion constants are consistent with this picture. A new formulation of the rigid bender model has produced plausible values for bond lengths and bending amplitudes for the isocyanides. The 14 N quadrupole coupling constants are discussed in terms of the approximate bending amplitudes. A description of the bonding in the molecules has been obtained using Townes–Dailey theory.

In situ monitoring of rapid vaporization process on a submicron length scale is essential for understanding the phenomena induced by pulsed-laser heating of solid surfaces in contact with liquids. A number of laser-processing applications including steam laser cleaning and liquid-assisted material ablation take advantage of enhanced acoustic excitation in the explosive vaporization process. In this paper, a novel technique based on Michelson interferometry is developed to study the liquid vaporization process induced by a KrF excimer-laser pulse ( λ =248 nm, full-width-half-maximum (FWHM) = 24 ns) at relatively low fluences typically used for laser cleaning processes. The dynamics of rapid vaporization in a highly superheated liquid layer is measured in a semi-quantitative manner. In addition, optical-reflectance and forward-scattering measurements are performed to elucidate the vaporization dynamics. The results suggest that separate bubble nuclei begin to grow in the early stage of vaporization and tend to coalesce later. The maximum bubble size and growth rate are estimated to be of the order of 0.1 μm and 1 m/s, respectively. The bubbles decay at a significantly slow rate in comparison with the growth rate. The interference probe detects the long-term acoustic cavitation, so called memory effect, more effectively than the previously employed reflectance probe. This study reveals that the acoustic enhancement in the laser induced vaporization process is caused by bubble expansion in the initial growth stage, not by bubble collapse.

CM1 (centrocyte/-blast marker 1) defined by a mAb developed against concanavalin-A activated PBMC, is expressed specifically on some tonsillar germinal center (GC) B cells. In single flow cytometric analysis, the bone marrow did not express these molecules nor did the PBMC or the thymocytes. The peripheral B lymphocytes showed more than 90% positive, while the peripheral T lymphocytes showed approximately 60% positive at 48 h after activation by PMA/ionomycin, respectively. A western blot analysis and an immunoprecipitation for CM1 showed a band at 70 kDa. Cross-linking of CM1 with anti-CM1 mAb induced apoptosis of the GC B cells (CD38(+)IgD(-)). Immunohistochemical staining revealed that the CM1 molecule is distributed over the entire area except the proximal dark zone of the tonsillar germinal centers. These results suggest that the CM1 molecule might be involved in differentiation of the germinal center B cells as one of the novel centrocyte markers.

Studies have been carried out on unique molecular non-rigidity of Cp*RhIII(PyS)2 (PyS=pyridine-2-thiolato). One PyS ligand bonds to the rhodium ion in an S-monodentate mode (RhS(2)=2.3799(9) A) while the other ligand chelates to the metal in an N,S-bidentate mode (RhS(1)=2.4380(9); RhN(1)=2.089(2) A). Both PyS ligands possess a significant contribution from the thiol tautomer in the solid state. Even though the conformation and configuration of the molecule are still retained in solution, an unusual metal-mediated tautomeric non-rigidity for the PyS region is observed in the solution around room temperature.

Initial experiments on infrared matrix-assisted laser desorption/ionization mass spectrometry (IR-MALDI) using a free electron laser in the analysis of low-molecular-weight compounds are reported. Mass spectra from samples of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) and a phosphate salt were obtained. Low molecular weight (LMW) compounds are of similar mass as the molecular weight of the matrix compound and interference between matrix and analyte ions can degrade MALDI sensitivity. Under optimal conditions, however, we find little interference and that often the analyte signal exceeds the matrix signal, a result also observed in UV-MALDI of these compounds. In the IR-MALDI of EDTA near 3.0 μm the FEL results are similar to those obtained using a fixed frequency 2.94 μm Er:YAG laser of 200 ns pulse duration. However, the tunable FEL laser can selectively excite particular vibrational modes of the matrix (e.g., an OH or CO stretch) or of residual water contained within the crystalline MALDI sample. This capability was used to explore possible vaporization and ionization mechanisms of IR-MALDI for EDTA.

CYP2C12 is a steroid hydroxylase cytochrome P450 whose female-specific expression in adult rat liver is transcriptionally activated by the continuous plasma growth hormone (GH) profile characteristic of adult female rats. DNase I footprinting and gel mobility shift analysis of the 5'-flank of the CYP2C12 gene were carried out to identify cis-acting elements and trans-acting factors that may contribute to the GH-regulated, sex-dependent transcription of this P450 gene. DNase I footprinting analysis revealed sex- and GH-regulated DNase I hypersensitivity sites at the boundaries of several protein binding sites detected along a 1560-nucleotide upstream segment of CYP2C12. Five distinct sites bound a novel continuous GH-regulated nuclear factor, GHNF, which is enriched in adult female and continuous GH-treated male liver nuclear extracts compared to untreated male liver nuclear extracts. Two other footprinted sites correspond to binding sites for the liver transcription factors C/EBP and albumin D element-binding protein and a third to an HNF1 binding site. A specific binding site for GHNF was also found in the 5'-proximal promoter of CYP2C11, an adult male-specific liver P450 gene, suggesting that GHNF may contribute to the down-regulation of that gene by continuous GH. GHNF was distinguished from the nuclear factors that bind to a GH response element upstream of the rat Spi 2.1 gene and is also distinct from the GH-activatable latent cytoplasmic transcription factors STAT 1, STAT 3, and STAT 5. These findings support the hypothesis that continuous GH-activated transcription of CYP2C12 in adult female rat liver (a) involves the activation of a novel GH-regulated nuclear factor which binds to multiple sites along the 5'-flank of this cytochrome P450 gene, and (b) proceeds via a signaling pathway distinct from the GH pulse-activated STAT5 pathway proposed to induce CYP2C11 and other male-expressed liver genes.

Chitinolytic enzymes such as beta-N-acetylglucosaminidases are major hydrolases involved in insect molting. By screening a Manduca sexta (tobacco hornworm) cDNA library with an antibody against beta-N-acetylglucosaminidase from molting fluid of M. sexta pharate pupae, several putative cDNA clones for this enzyme were isolated. The longest of the cDNA clones has an insert of approximately 3 kb, and the complete nucleotide sequence was determined. Because this clone is missing the initiation codon and nucleotides corresponding to the leader peptide, the mRNA 5'-end sequence was determined by PCR (polymerase chain reaction) amplification and cycle sequencing. The sequence of the encoded protein from positions 23 to 35 is identical to the NH2-terminal sequence of one of the beta-N-acetylglucosaminidases isolated from pharate pupal molting fluid. The amino acid sequence is similar to those of silkworm, human, mouse, bacterial, and several other beta-N-acetylglucosaminidases. Two highly conserved regions in the amino acid sequence were found in all members of this family. Southern blot analysis suggested that the number of genes in the Manduca genome closely related to the cDNA clone may be as few as one. The beta-N-acetylglucosaminidase gene is expressed most abundantly in epidermal and gut tissues on days 6 and 7 of fifth instar larvae. Injection of 20-hydroxyecdysone induced expression of the beta-N-acetylglucosaminidase gene, whereas topical application of the juvenile hormone analog, fenoxycarb, suppressed the inductive effect of molting hormone.

Intermittent plasma growth hormone (GH) pulses, which occur in male but not female rats, activate liver Stat 5 by a mechanism that involves tyrosine phosphorylation and nuclear translocation of this latent cytoplasmic transcription factor (Waxman, D. J., Ram, P. A., Park, S. H., and Choi, H. K. (1995) J. Biol. Chem. 270, 13262-13270). We demonstrate that physiological levels of GH can also activate Stat 1 and Stat 3 in liver tissue, but with a dependence on the dose of GH and its temporal plasma profile that is distinct from Stat 5 and with a striking desensitization following a single hormone pulse that is not observed with liver Stat 5. GH activation of the two groups of Stats leads to their selective binding to DNA response elements upstream of the c-fos gene (c-sis-inducible enhancer element; Stat 1 and Stat 3 binding) and the beta-casein gene (mammary gland factor element; liver Stat 5 binding). In addition to tyrosine phosphorylation, GH is shown to stimulate phosphorylation of these Stats on serine or threonine in a manner that either enhances (Stat 1 and Stat 3) or substantially alters (liver Stat 5) the binding of each Stat to its cognate DNA response element. These findings establish the occurrence of multiple, Stat-dependent GH signaling pathways in liver cells that can target distinct genes and thereby contribute to the diverse effects that GH and its sexually dimorphic plasma profile have on liver gene expression.

Growth hormone (GH) exerts sexually dimorphic effects on liver gene transcription that are regulated by the temporal pattern of pituitary GH release, which is intermittent in male rats and nearly continuous in females. To investigate the influence of these GH secretory patterns on intracellular hepatocyte signaling, we compared the pattern of liver nuclear protein tyrosine phosphorylation in male and female rats. An Mr ~93,000 polypeptide, p93, was found to be tyrosine phosphorylated to a high level in male but not female rats. GH, but not prolactin, rapidly stimulated p93 tyrosine phosphorylation in hypophysectomized rats. Intermittent plasma GH pulses triggered repeated p93 phosphorylation, while continuous GH exposure led to desensitization and a dramatic decline in liver nuclear p93. p93 was cross-reactive with two monoclonal antibodies raised to mammary Stat 5, whose tyrosine phosphorylation is stimulated by prolactin. Intermittent GH pulsation translocated liver Stat 5/p93 protein from the cytosol to the nucleus and also activated its DNA binding activity, as demonstrated using a mammary Stat 5-binding DNA element derived from the β-casein gene. p93 is thus a liver-expressed, Stat 5-related DNA binding protein that undergoes tyrosine phosphorylation and nuclear translocation in response to intermittent plasma GH stimulation and is proposed to be an intracellular mediator of the stimulatory effects of GH pulses on male-specific liver gene expression.

Insects use chitinolytic enzymes to digest chitin in the exoskeleton during the molting process. We have isolated and sequenced a chitinase-encoding cDNA from the tobacco hornworm, Manduca sexta, compared its sequence with genes encoding chitinolytic enzymes from other sources, and studied chitinase gene expression and hormonal regulation during the larval-pupal transformation. The insert DNA in this clone is 2452 nucleotides long with an open reading frame of 1662 nucleotides that encodes a protein of 554 amino acids with a molecular weight of 62 kDa. Several regions of the amino acid sequence in this protein are similar to sequences in yeast, cucumber and bacterial endo-beta-N-acetylglucosaminidases. Hybrid-selection of mRNA and in vitro translation yielded an immunoreactive protein with an apparent molecular mass of 75 kDa, which is similar to the size of a chitinase present in pharate pupal molting fluid. Southern blot analysis indicated that one or two genes related to the cDNA clone are encoding chitinases in the Manduca genome. The major tissues expressing chitinase genes were the epidermis and gut with mRNA levels highest on c. days 5-7 during the fifth larval instar. Injection of 20-hydroxyecdysone into ligated fifth instar abdomens caused about a 10-fold increase in mRNA levels in both epidermis and gut, and topical application of the juvenile hormone mimic, fenoxycarb, suppressed the ecdysteroid-induced accumulation of chitinase RNA.

Interactions of pulsed laser irradiation with matter may lead to controlled phase change transformations and material structure modifications. During transient heating at the nanosecond scale, the thermal gradients across the heat affected zone are accompanied by changes in the material complex refractive index. These changes, coupled with wave interference, modify the energy absorption, and thus the temperature field in the target material. This work accounts for these effects in a rigorous manner using thin film optics theory. Results are presented for the induced temperature field in thin silicon films by pulsed ruby and Nd:YAG laser light.

Melting and solidification of a silicon film by continuous wave laser beam irradiation has been studied. The silicon film melting and recrystallization is controlled by the temperature distribution in the semiconductor. Numerical calculations have been carried out for a range of laser beam parameters and material translational speeds. The results for the melt pool size have been compared with experimental data. The temperature field development has also been monitored with localized reflectivity measurements. Experimental and predicted transient reflectivity distributions have been compared.