Experimental Observations of Laser-Driven Tin Ejecta Microjet Interactions.

The study of high-velocity particle-laden flow interactions is of importance for the understanding of a wide range of natural phenomena, ranging from planetary formation to cloud interactions. Experimental observations of particle dynamics are sparse given the difficulty of generating high-velocity flows of many particles. Ejecta microjets are micron-scale jets formed by strong shocks interacting with imprinted surfaces to generate particle plumes traveling at several kilometers per second. As such, the interaction of two ejecta microjets provides a novel experimental methodology to study interacting particle streams. In this Letter, we report the first time sequences of x-ray radiography images of two interacting tin ejecta microjets taken on a platform designed for the OMEGA Extended Performance (OMEGA EP) laser. We observe that the microjets pass through each other unattenuated for the case of 11.7±3.2 GPa shock pressures and jet velocities of 2.2±0.5 km/s but show strong interaction dynamics for 116.0±6.1 GPa shock pressures and jet velocities of 6.5±0.5 km/s. We find that radiation-hydrodynamic simulations of the experiments are able to capture many aspects of the collisional behavior, such as the attenuation of jet velocity in the direction of propagation, but are unable to match the full spread of the strongly interacting cloud.

The origin of local strain in highly epitaxial oxide thin films.

The ability to control the microstructures and physical properties of hetero-epitaxial functional oxide thin films and artificial structures is a long-sought goal in functional materials research. Normally, only the lattice misfit between the film and the substrate is considered to govern the physical properties of the epitaxial films. In fact, the mismatch of film unit cell arrangement and the Surface-Step-Terrace (SST) dimension of the substrate, named as "SST residual matching", is another key factor that significantly influence the properties of the epitaxial film. The nature of strong local strain induced from both lattice mismatch and the SST residual matching on ferroelectric (Ba,Sr)TiO3 and ferromagnetic (La,Ca)MnO3 thin films are systematically investigated and it is demonstrated that this combined effect has a dramatic impact on the physical properties of highly epitaxial oxide thin films. A giant anomalous magnetoresistance effect (~10(10)) was achieved from the as-designed vicinal surfaces.

Radiographic and histologic evaluation of platelet-rich plasma and bovine-derived xenograft combination in bilateral sinus augmentation procedure.

There is currently a great interest regarding the use of platelet-rich plasma (PRP) in combination with various bone graft materials in sinus lift procedures. The purpose of this study was to assess and compare the radiographic and histological results of sinus augmentation procedures following treatment with PRP/bovine-derived xenograft (BDX) vs. BDX/collagen membrane. Using a split mouth design, 10 patients, with ≤5 mm of residual alveolar bone in the vertical direction, were treated with PRP/BDX or BDX/collagen membrane. At 8 months after surgery, both graft materials led to a satisfactory increase in vertical dimensions of bone. Bone biopsies were taken from the augmented sites during the implant placement. Histological analysis demonstrated that majority of the trabecula contained orderly layered lamellar bone in the PRP/BDX group, whereas mainly woven bone with a haphazard arrangement of collagen fibers were noticed in the BDX /collagen membrane group. It can be concluded that both combinations resulted with a satisfactory bone height, but more prominent and mature bone formation was observed at sites treated with PRP/BDX.

[Root resection in the era of dental implants].

The treatment of furcation defects is one of the most challenging aspects of periodontal therapy. The periodontal therapist can utilize various treatment modalities, including: non surgical root debridement, local drug delivery, open flap surgery, tunneling, root resection, guided tissue regeneration and extraction. Each treatment method has its advantages and disadvantages. The dilemmas concerning tooth prognosis and prosthetic considerations in such cases are especially demanding, especially in comparison to implant therapy. The clinician's decision in these situations must comply with the objective condition in the particular case based on his abilities and knowledge and the patient expectations. In order to evaluate the relevancy of root resection procedures we reviewed the literature focusing on root resection therapy prognosis as well as the different therapeutic alternatives for furcated molar teeth. Root resection treatment guidelines, indications and contraindication are presented along with clinical examples. Root resection is currently a relevant treatment modality for furcation defects. By using proper case selection, good surgical technique, proper prosthetic treatment and good periodontal supportive care, a good 5 year prognosis can be achieved and complications can be minimized. In light of the growing literature concerning dental implants complications, extraction and dental implant placement should be recommended as the last option when all other conservative options cannot be used, or following their failure.

[Using acellular dermal matrix (ADM) allograft in periodontal surgery--a literature review and case reports].

The acellular dermal matrix (ADM) allograft is widely used in periodontal surgery. A MEDLINE search was performed for retrieving related articles. This article reviews ADM processing and mode of use, indications and contraindications, surgical techniques and clinical results for the treatment of localized and generalized gingival recessions with ADM and comparisons with other methods of treatment for root recessions. Two case reports are presented, illustrating the use of ADM and connective tissue grafts for root coverage.

Identification and functional clustering of global gene expression differences between age-related cataract and clear human lenses and aged human lenses.

We have examined the gene expression profiles of young, old and cataractous human lenses in order to differentiate those gene expression changes specific for cataract from those also associated with lens aging. Differentially expressed transcripts were identified by oligonucleotide microarray analysis and clustered according to their known functions. Four hundred and twelve transcripts that are increased and 919 transcripts that are decreased were identified at the 2-fold or greater level between epithelia isolated from cataract relative to clear lenses while 182 transcripts that are increased and 547 transcripts that are decreased were identified at the 2-fold or greater level between young and old lens epithelia. Comparison of the cataract gene expression changes with those detected in lens aging revealed that only 3 transcripts exhibited similar trends in gene expression. These data suggest that cataract- and age-specific changes in gene expression do not overlap and provide evidence for multiple cataract- and age-specific gene expression changes in the human lens.

[Resonance frequency analysis in immediate loading of dental implants].

Immediate loading of dental implants aims to shorten treatment time. Stability at implant insertion is critical to success. The aim of this prospective study is to compare primary implant stability, measured by insertion torque (IT) with resonance frequency analysis (RFA) expressed as ISQ. Patients requiring implant therapy were treated by teeth extractions, placement of 1-9 MIS implants, bone augmentation as needed and fixed provisional restorations. We measured IT and ISQ for non-submerged loaded (NSL), non-submerged non loaded (NSNL) and submerged (S) implants. 14 patients, aged 34-79 years, were recruited. 53 implants were inserted (38 maxillary & 15 mandibular). 30 implants, 18 in fresh extraction sites, were immediately loaded. ISQ was 63.3 +/- 2.8 (S.E.), 67.2 +/- 3.5 (S.E.) and 58.8 +/- 2.7 for the NSL, NSNL and S groups, respectively (p = 0.0459). IT was 40.4 +/- 1.8 Ncm, 46 +/- 4.0 and 35.3 +/- 2.1 (p = 0.0646). ISQ and IT were not statistically different between extraction vs. non-extraction and augmented vs. non-augmented sites. We found a significant difference in IT between maxillary & mandibular sites, and a significant correlation between ISQ & IT and between ISQ & implant diameter. These data suggest that ISQ is correlated to IT and is influenced mainly by implant diameter and not by implant length, location or bone level. Finally, a case including immediate implants, bone augmentation and immediate provisional restoration is presented.

[Implant fracture: a complication of treatment with dental implants--review of the literature].

Dental implants are a functional and esthetic solution to partial and total edentulism. The initial success rate of this treatment modality is 90-95%. But, that treatment modality is not free of complications. One of the rare complications yet, with severe clinical results is fracture of dental implants. The current literature review presents the various causative factors that may lead to implant fracture. Implant failures may be sorted into groups by the timing of their appearance, or by the origin of failure. Fractures belong to the group of late complications, caused by a biomechanical overload. Overload may be caused by inappropriate seat of the superstructure, in-line arrangement of the implants, leverage, heavy occlusal forces (bruxing, clenching), location of the implant and the size of the implant or metal fatigue. Good clinical examinations and correct treatment plans may reduce the risk of implant fracture.

New insight into enhanced superconductivity in metals near the metal-insulator transition.

We have studied the transport properties of disordered WSi films near the metal/insulator transition (MIT) and we have also reviewed the data for several other disordered materials near their MIT. In all cases, we found the presence of enhanced superconductivity. We constructed a superconductivity "phase diagram" (i.e., T(c) versus sigma) for each system, which reveals a striking correlation: In all cases, T(c) values are significantly enhanced only for samples whose conductivities lie within a narrow range on the metallic side of, and moderately near, the MIT. We present a heuristic model to explain this phenomenon.

J3-crystallin of the jellyfish lens: similarity to saposins.

J3-crystallin, one of the three major eye-lens proteins of the cubomedusan jellyfish (Tripedalia cystophora), shows similarity to vertebrate saposins, which are multifunctional proteins that bridge lysosomal hydrolases to lipids and activate enzyme activity. Sequence alignment of deduced J3-crystallin indicates two saposin-like motifs arranged in tandem, each containing six cysteines characteristic of this protein family. The J3-crystallin cDNA encodes a putative precursor analogous to vertebrate prosaposins. The J3-crystallin gene has seven exons, with exons 2-4 encoding the protein. Exon 3 encodes a circularly permutated saposin motif, called a swaposin, found in plant aspartic proteases. J3-crystallin RNA was found in the cubomedusan lens, statocyst, in bands radiating from the pigmented region of the ocellus, in the tentacle tip by in situ hybridization, and in the embryo and larva by reverse transcription-PCR. Our data suggest a crystallin role for the multifunctional saposin protein family in the jellyfish lens. This finding extends the gene sharing evolutionary strategy for lens crystallins to the cnidarians and indicates that the putative primordial saposin/swaposin J3-crystallin reflects both the chaperone and enzyme connections of the vertebrate crystallins.

Nitration and inactivation of tyrosine hydroxylase by peroxynitrite.

Tyrosine hydroxylase (TH) is modified by nitration after exposure of mice to 1-methyl-4-phenyl-1,2,3,6-tetrahydrophenylpyridine. The temporal association of tyrosine nitration with inactivation of TH activity in vitro suggests that this covalent post-translational modification is responsible for the in vivo loss of TH function (Ara, J., Przedborski, S., Naini, A. B., Jackson-Lewis, V., Trifiletti, R. R., Horwitz, J., and Ischiropoulos, H. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 7659-7663). Recent data showed that cysteine oxidation rather than tyrosine nitration is responsible for TH inactivation after peroxynitrite exposure in vitro (Kuhn, D. M., Aretha, C. W., and Geddes, T. J. (1999) J. Neurosci. 19, 10289-10294). However, re-examination of the reaction of peroxynitrite with purified TH failed to produce cysteine oxidation but resulted in a concentration-dependent increase in tyrosine nitration and inactivation. Cysteine oxidation is only observed after partial unfolding of the protein. Tyrosine residue 423 and to lesser extent tyrosine residues 428 and 432 are modified by nitration. Mutation of Tyr(423) to Phe resulted in decreased nitration as compared with wild type protein without loss of activity. Stopped-flow experiments reveal a second order rate constant of (3.8 +/- 0.9) x 10(3) m(-1) s(-1) at pH 7.4 and 25 degrees C for the reaction of peroxynitrite with TH. Collectively, the data indicate that peroxynitrite reacts with the metal center of the protein and results primarily in the nitration of tyrosine residue 423, which is responsible for the inactivation of TH.

The outcome of teeth with periapical periodontitis treated with nonsurgical endodontic treatment: a computerized morphometric study.

OBJECTIVES: This study investigated the prognosis for successful endodontic treatment and the correlation between the size of the periapical lesion, the quality of the root canal treatment, and the type of coronal restoration. METHOD AND MATERIALS: Periapical radiographs of 319 teeth with periapical periodontitis were studied. The area of each lesion was measured before treatment and 1 to 12 years after completion of the endodontic treatment. The measurements were performed using computerized morphometry. RESULTS: In 65.2% of the teeth, the size of the lesion decreased, while in 34.8% of teeth, there was an increase. Lesions larger than 10 mm2 had a greater tendency for healing. CONCLUSION: No significant correlation was found between the quality of root canal treatment, the type of the coronal restoration, and the success rate of the endodontic treatment.

Pro-apoptotic interactions between XK469 and the peripheral benzodiazepine receptor.

XK469 (2-[4-(7-chloro-2-quinoxalinyloxy) phenoxy]propionic acid) is a new anti-tumor agent with substantial activity against several drug-resistant cell lines. Using murine leukemia L1210 cells in culture, we found the chiral R(+) form of XK469 to be substantially more cytotoxic than the S(-) form, while the herbicide analog 'Assure' was essentially inactive. The cytotoxic response to these agents was accompanied by apoptosis, and was found to be correlated with drug binding to the peripheral benzodiazepine receptor in cell culture, suggesting that receptor binding may be a factor in drug-induced cytotoxicity.

Presence of a phospholipase D (PLD) distinct from PLD1 or PLD2 in human neutrophils: immunobiochemical characterization and initial purification.

Utilizing the transphosphatidylation reaction catalyzed by phospholipase D (PLD) in the presence of a primary alcohol and the short-chain phospholipid PC8, we have characterized the enzyme from human neutrophils. A pH optimum of 7.8-8.0 was determined. PIP(2), EDTA/EGTA, and ATP were found to enhance basal PLD activity in vitro. Inhibitory elements were: oleate, Triton X-100, n-octyl-beta-glucopyranoside, divalent cations, GTPgammaS and H(2)O(2). The apparent K(m) for the butanol substrate was 0.1 mM and the V(max) was 6.0 nmol mg(-1) h(-1). Immunochemical analysis by anti-pan PLD antibodies revealed a neutrophil PLD of approximately 90 kDa and other bands recognized minimally by anti-PLD1 or anti-PLD2 antibodies. The 90-kDa protein is tyrosine-phosphorylated upon cell stimulation with GM-CSF and formyl-Met-Leu-Phe. Protein partial purification using column liquid chromatography was performed after cell subfractionation. Based on the enzyme's regulatory and inhibitory factors, and its molecular weight, these data indicate an enzyme isoform that might be different from the mammalian PLD1/2 forms described earlier. The present results lay the foundation for further purification of this granulocyte PLD isoform.

Design, synthesis, and biological evaluation of analogues of the antitumor agent, 2-(4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy)propionic acid (XK469).

2-(4-[(7-Chloro-2-quinoxalinyl)oxy]phenoxy)propionic acid (XK469) is among the most highly and broadly active antitumor agents to have been evaluated in our laboratories and is currently scheduled to enter clinical trials in 2001. The mechanism or mechanisms of action of XK469 remain to be elaborated. Accordingly, an effort was initiated to establish a pharmacophore hypothesis to delineate the requirements of the active site, via a comprehensive program of synthesis of analogues of XK469 and evaluation of the effects of structural modification(s) on solid tumor activity. The strategy formulated chose to dissect the two-dimensional parent structure into three regions-I, ring A of quinoxaline; II, the hydroquinone connector linkage; and III, the lactic acid moiety-to determine the resultant in vitro and in vivo effects of chemical alterations in each region. Neither the A-ring unsubstituted nor the B-ring 3-chloro-regioisomer of XK469 showed antitumor activity. The modulating antitumor effect(s) of substituents of differing electronegativities, located at the several sites comprising the A-ring of region I, were next ascertained. Thus, a halogen substituent, located at the 7-position of a 2-(4-[(2-quinoxalinyl)oxy]phenoxy)propionic acid, generated the most highly and broadly active antitumor agents. A methyl, methoxy, or an azido substituent at this site generated a much less active structure, whereas 5-, 6-, 8-chloro-, 6-, 7-nitro, and 7-amino derivatives all proved to be essentially inactive. When the connector linkage (region II) of 1 was changed from that of a hydroquinone to either a resorcinol or a catechol derivative, all antitumor activity was lost. Of the carboxylic acid derivatives of XK469 (region III), i.e., CONH2, CONHCH3, CON(CH3)2, CONHOH, CONHNH2, CN, or CN4H (tetrazole), only the monomethyl- and N,N-dimethylamides proved to be active.

Chaperone function of mutant versions of alpha A- and alpha B-crystallin prepared to pinpoint chaperone binding sites.

A major stress protein, alpha-crystallin, functions as a chaperone. Site-directed mutagenesis has been used to identify regions of the protein necessary for chaperone function. In this work we have taken some of the previously described mutants produced and assessed their chaperone function by both a traditional heat-induced aggregation method at elevated temperature and using enzyme methods at 37 degrees C. In general the different assays gave parallel results indicating that the same property is being measured. Discrepancies were explicable by the heat lability of some mutants. Most mutants had full chaperone function showing the robust nature of alpha-crystallin. A mutant corresponding to a minor component of rodent alpha A-crystallin, alpha Ains-crystallin, had decreased chaperone function. Decreased chaperone function was also found for human Ser139--> Arg, Thr144-->Arg, Ser59-->Ala mutants of alpha B-crystallin and double mutants Ser45-->Ala/Ser59-->Ala, Lys103--> Leu/His104-->Ile, and Glu110-->His/His111-->Glu. A mutant Phe27-->Arg that was the subject of previous controversy was shown to be fully active at physiological temperatures.

Development of cataractous macrophthalmia in mice expressing an active MEK1 in the lens.

PURPOSE: To characterize the extracellular signal-regulated kinase (ERK) pathway in the lens and to try to understand how this pathway contributes to lens function and cataractogenesis. METHODS: The members of the ERK pathway in the lens were examined by Western blotting, immunohistochemical staining, and kinase assay. A gain-of-function approach was used to perturb the ERK pathway in the lenses of transgenic mice via expression of a constitutively active mutant of the mitogen-activated protein kinase kinase 1 (MEK1(E)), the direct upstream kinase of the ERK1 and ERK2 kinases, under the alphaA-crystallin promoter. RESULTS: The presence of an active ERK pathway was found in lens epithelial cells and in differentiating fibers. Transgenic mice that expressed MEK1(E) developed postnatal cataracts as well as macrophthalmia. Distinct morphologic alterations, such as lens enlargement, swelling fiber cells, enlarged extracellular space, and vacuole formation, were observed in the lenses of these transgenic mice. A significant increase in the glucose transporter 1 (GLUT1) level, as well as in the glucose level, was detected in the lens. CONCLUSIONS: The MAP kinase pathway is involved in the regulation of glucose metabolism and balance in the mouse lens. Moreover, the alteration of MAP kinase activity in the lens is sufficient to cause cataract formation with enlarged extracellular space and vacuoles in the differentiating fibers. This transgenic mouse may provide a useful model for understanding the mechanism(s) for some aspects of human cataracts.

Surgical complications after primary nephrectomy for Wilms' tumor: report from the National Wilms' Tumor Study Group.

BACKGROUND: Surgical complications are a recognized morbidity of the treatment of patients with Wilms tumor. This study examines the incidence of surgical complications in the most recently completed study from the National Wilms' Tumor Study Group (NWTSG). STUDY DESIGN: The fourth National Wilms' Tumor Study (NWTS-4) enrolled 3,335 patients from August 1986 to August 1994. A random sample of 534 patients was selected from 2,290 eligible patients randomized to treatment regimens or enrolled in the followed category and treated according to NWXTSG protocol. The patient records received at the NWTSG Data and Statistical Center were analyzed for surgical complications (intraoperative and postoperative). RESULTS: Sixty-eight patients (12.7%) experienced 76 complications. Intestinal obstruction was the most common complication (5.1% of patients), followed by extensive hemorrhage (1.9%), wound infection (1.9%), and vascular injury (1.5%). The incidence of surgical complications in NWTS-4 was significantly lower than NWTS-3 (12.7% versus 19.8%, p < 0.001). There has been a marked decrease in the risk of extensive intraoperative bleeding and major intraoperative complications. Factors previously shown to be associated with an increased risk for surgical complications, together with indicators of type of hospital and surgeon specialty, were analyzed by multiple logistic regression analysis. Intravascular extension into the inferior vena cava (IVC), the atrium, or both (p = 0.02; odds ratio [OR] 3.8, 95% confidence interval [CI] 1.2, 11.8), and nephrectomy performed through a flank or paramedian incision (p = 0.02; OR 5.3, 95% CI 1.3, 22) were both associated with increased risk of complications. Tumor diameter greater than or equal to 10cm was also associated with an increased risk of surgical complications (p = 0.05; OR 2.0, 95% CI 1.0, 3.9). The risk of complications was higher if the nephrectomy was performed by a general surgeon (OR 9.0, 95% CI 1.3, 65; p = 0.03) rather than a pediatric surgeon (reference group, OR 1.0) or pediatric urologist (OR 0.7, 95% CI 0.3, 1.8). CONCLUSIONS: The incidence of surgical complications in NWTSG patients undergoing primary nephrectomy has significantly decreased over the past decade. But surgical morbidity should not be overlooked. It is important that surgeons treating young children with solid tumors are aware of their role and the potential risks encountered in removal of the primary tumor. This study found that surgical specialists who primarily treat children can perform these operations with lower surgical morbidity.

Amine fluoride/stannous fluoride and chlorhexidine mouthwashes as adjuncts to surgical periodontal therapy: a comparative study.

BACKGROUND: Postsurgical mouthwashes are routinely used in clinical studies and also in daily clinical practice. Chlorhexidine gluconate (CHX) has long been the gold standard for supra-gingival chemical plaque control regimens. Amine fluoride/stannous fluoride (AmF/SnF2) formulations have also been extensively studied and shown to have an antibacterial effect and be useful as antiplaque agents. The antibacterial effect of AmF/SnF2 and its minimal extrinsic tooth staining make it a possible alternative to CHX as an adjunct to periodontal surgical therapy. The aim of this double-blind, controlled clinical trial was to evaluate and compare the combined effect of an AmF/SnF2 or a CHX mouthwash and surgical periodontal therapy on periodontal parameters. METHODS: Thirty-two patients with at least 3 pockets > or =5 mm in the same quadrant were selected for this study, following a hygienic phase of therapy. They were randomized into 2 treatment groups: surgical flap debridement and a postsurgical CHX mouthwash or surgical flap debridement and an AmF/SnF2 postsurgical mouthwash, performed twice daily for 3 weeks. Clinical measurements were taken at baseline and 3 and 12 weeks postsurgery. RESULTS: Both treatment modalities resulted in significant improvements in probing depth and clinical attachment level. There was no significant difference between groups in any of the recorded parameters. Staining index at week 3 in the CHX group was significantly higher than in the AmF/SnF2 group (P<0.05). However these differences leveled down at 12 weeks. CONCLUSIONS: Our results support the alternative use of an AmF/SnF2 mouthwash in plaque control management of patients following flap debridement surgery.