Silicoating in resin-metal bonding: restorative implications for osseointegrated implant-bone unison.

Detailed background information leading to the development of a silicoating technique is presented with its advantages and disadvantages and its role in implant dentistry. The rationale is shown for coining a new acronym "osseointegrated Implant-Bone Unison" with an interest in biomechanical considerations for a prosthodontic restorative scenario. Several clinical cases are presented that involve silicoating and composite restorations.

Increase in brain nitric oxide synthase activity in daunorubicin-treated rats.

Anthracyclines such as daunorubicin are very effective anticancer agents. These drugs are known to cause side effects including cardiotoxicity. Anthracyclines are neurotoxic to laboratory animals.

Characterization of primary human fibroblasts transformed by human papilloma virus type 16 and herpes simplex virus type 2 DNA sequences.

Human papilloma virus type 16 (HPV-16) and herpes simplex virus type 2 (HSV-2) are human viruses implicated in the development of cancer, in particular cervical cancer. The ability of HSV-2 and HPV-16 to transform early passage human cells was examined in this report. For these studies, gingival fibroblasts were utilized.

Herpesviral deoxythymidine kinases contain a site analogous to the phosphoryl-binding arginine-rich region of porcine adenylate kinase; comparison of secondary structure predictions and conservation.

Twelve herpesviral deoxythymidine kinases were examined for regions of sequence similarity by multiple alignment. Six highly conserved sites were observed. Site 1 corresponded to a glycine-rich loop that forms part of the ATP-binding pocket in porcine adenylate kinase (PAK), and site 5 corresponded to a region in PAK, located on one lobe of the cleft, that contains arginine residues that bind substrate phosphoryl groups.

Equine herpes virus 1 and pseudorabies virus resistance to 2'-fluoropyrimidine analogs and to bromovinyldeoxyuridine: implications for dTMP kinase activity.

The 2'-fluoropyrimidine nucleoside analogs 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC). 1(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-methyluracil (FMAU), and 1(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouracil (FIAU) showed higher in vitro activity against herpes simplex virus type 1 (HSV-1), than equine herpesvirus 1 (EHV-1) or pseudorabies virus (PRV). Comparison of the 50% plaque inhibitory doses for HSV-1 and its mutant MMdUr-20 in cell cultures with inhibition constants (Ki's) for the viral deoxythymidine kinases (dTKs) suggests that in the infected cell FMAU is phosphorylated by host enzymes.

Studies on interactions of dTK-HSV mutants with neurons in vitro.

Thymidine kinase negative (dTK-) mutants of herpes simplex virus type 1 (HSV-1) multiplied well in rat brain glioma cells. A proportion (less than 1%) of glioma cells survived the infection with HSV and were designated "survivor" glioma cells. Survivor cells of dTK- mutant virus infection ceased to produce infectious virus after two passages and were highly resistant to both HSV-1 and HSV-2 but not to vesicular stomatitis virus (VSV).

HSV1-specific thymidylate kinase activity in infected cells.

Several 5-methoxymethyldeoxyuridine (MMdU)-resistant mutants of herpes simplex virus type 1 (HSV1) were classified by measuring their sensitivities to the deoxythymidine kinase (dTK)-dependent antiviral drugs 9-(2-hydroxyethoxymethyl)-guanine (acyclovir, ACV), 1-beta-D-arabinofuranosylthymine (araT), and E-(2)-5-bromovinyldeoxyuridine (BVdU) and to the dTK-independent antiviral drug phosphonoacetate (PAA). Compared to wild-type (WT) virus, all five of the dTK- mutants were highly resistant (greater than or equal to 500-fold) to BVdU and MMdU, moderately resistant to ACV (50- to 100-fold) and araT (10- to 20-fold), but not resistant to PAA. The dTK of the mutant MMdUr-20 (dTK+) appeared to phosphorylate dTMP less well than that of the WT virus, while its affinity for deoxythymidine was not altered.

Herpes simplex virus type 1 and neuronal cells--a special cell-virus interaction.

Rat brain glioma cells were semipermissive for herpes simplex virus (HSV) replication, because the growth of HSV was multiplicity-dependent in these cells. By using this property, we successfully isolated 'survivor' glioma cells following HSV infection at low multiplicity and without using any special treatment (such as UV irradiation) either of the cells or of the virus. Under the same conditions there were no survivor BHK or 3T3 cells, which suggests the uniqueness of the glioma cell-HSV interaction.

Alterations in the recognition of nucleoside analogues as substrates by the deoxythymidine kinase of a 5-methoxymethyldeoxyuridine-resistant mutant of herpes simplex virus type 1.

Inhibition constants (Kis) were used as an estimate of the ability of various nucleoside analogues to be recognized as substrates by the deoxythymidine kinases (dTKs) of a 5-methoxymethyldeoxyuridine-resistant (MMdUr) mutant of herpes simplex virus type 1 (HSV-1) and its parent wild-type (wt). It was found that the Kis for the 5-position analogues MMdU, [E]-5-(2-bromovinyl)deoxyuridine, bromodeoxyuridine and iododeoxyuridine were increased approximately three-to fivefold, suggesting that they were poorer substrates for the MMdUr dTK than for the wt dTK. With the 2' analogues arabinosylthymine and 2' fluoro 5-methylarabinosyluracil, however, the Kis were increased to a much greater extent, 80- and 240-fold, respectively.

Alterations in substrate specificity and physicochemical properties of deoxythymidine kinase of a drug-resistant herpes simplex virus type 1 mutant.

The deoxythymidine kinase (dTK) activity of a 5-methoxymethyldeoxyuridine-resistant mutant (MMdU(r)-20) of herpes simplex virus type 1 was compared with that of the parental wild-type (WT) virus. The dTK activity induced by the mutant was consistently less than that induced by the WT virus, was inhibited by antibody specific for herpes simplex virus dTK, and was more thermostable than the WT dTK. Further, it was inhibited to a lesser degree than the WT dTK by the nucleoside analogs MMdU and arabinosylthymine (araT), which suggests that one of the effects of the mutation was a selective alteration in substrate recognition by the dTK.

Thymine salvage, mitochondria, and the evolution of the herpesviruses.

The salvage of thymine is an apparently ubiquitous feature of free-living lifeforms as well as of mitochondria, chloroplasts and most of the large DNA viruses. Assumptions and data are described which explain the evolution of thymine salvage in prokaryotes, animal cells, and large DNA viruses, in terms of deoxythymidine kinase and its relationship to mitochondria. Specifically, it is suggested that regulation of deoxythymidine kinase (by end-product inhibition) has evolved as a means of assuring a constant supply of thymine compounds for the mitochondria and that the degree to which this regulation is present in the deoxythymidine kinases of the various herpesviruses correlates with the degree of dependence of their replicative cycle on the continued health of the mitochondria of their host cells.

Temperature-induced structural stabilization of the encapsidated RNA of southern bean mosaic virus and its biologic significance.

Virions of southern bean mosaic virus (SBMV) show two distinct sensitivity patterns upon heating. Infectivity loss and capsid denaturation occur concurrently if virions are exposed at 50-55 degrees in 0.1 M sodium phosphate buffer, pH 7.

Suggestions for the classification and nomenclature of helical plant viruses.

Helical plant viruses are arranged into four families: Flexiviridae, Tobamoviridae, Hordeiviridae, and Tobraviridae. Further division of these families into genera and subgenera is shown. A family-specific, constant amount of RNA per unit virion length and a distinct radial location of RNA from the center of the helix are considered as basic criteria for establishment of these families.

Differentiation of legume carlaviruses based on their biochemical properties.

Nucleic acids of alfalfa latent virus (ALV), pea streak virus (PSV), and red clover vein mosaic virus (RCVMV) were hydrolyzed by pancreatic RNase but not by DNase. ALV and PSV each had one single-stranded RNA of 38.0 and 37.