Reduced mortality in murine cytomegalovirus infected mice following prophylactic murine interferon-gamma treatment.

Efficacy of recombinant DNA-derived murine IFN-gamma was investigated in a murine model of cytomegalovirus infection. Treatment of 3-week-old Swiss Webster mice with murine IFN-gamma prior to infection with murine cytomegalovirus (MCMV) significantly reduced mortality due to MCMV infection. Efficacy was dose-dependent and was observed using either intraperitoneal or intramuscular injection as the route of administration. Two doses, one at 24 h and one at 4 h prior to MCMV infection, were required for optimum efficacy, and doses administered after MCMV infection had no apparent effect. Reduced infectious MCMV titers were observed in critical organs of IFN-gamma treated mice and histopathologic lesions induced by MCMV infection were in general less severe and resolved sooner than lesions in untreated mice. Results in this murine model of cytomegalovirus infection suggest that IFN-gamma treatment may be useful as prophylactic therapy for human cytomegalovirus infections when a high probability of exposure to the virus exists and consequences of infection may be severe.

Effects of tumor necrosis factor-alpha treatment on mortality in murine cytomegalovirus-infected mice.

The effects of treatment with recombinant DNA-derived Tumor Necrosis Factor-alpha (TNF-alpha) in a murine model of cytomegalovirus infection were investigated. Treatment of 3-week-old Swiss Webster mice with murine TNF-alpha prior to infection with murine cytomegalovirus (MCMV) had no demonstrable effect on mortality. However, if mice were treated prior to infection with a combination of murine IFN-gamma and murine TNF-alpha, the dose of IFN-gamma required to achieve significant reduction in mortality was reduced by a factor > 10. In contrast to the beneficial effects of prophylactic TNF-alpha treatment in combination with IFN-gamma, TNF-alpha treatment of mice after MCMV infection resulted in increased mortality. The increased mortality occurred when nonlethal doses of TNF-alpha were used and required virus replication. The effects of TNF-alpha treatment on mortality in MCMV-infected mice were not predicted from cell culture experiments which evaluated the effects of TNF-alpha treatment on MCMV replication in primary mouse embryo fibroblasts.

A comparative clinical investigation of a novel toothbrush designed to enhance plaque removal efficacy.

PURPOSE: To investigate the safety and efficacy of a new toothbrush with a novel brush head design (Oral-B CrossAction) in comparison with seven leading manual brushes. MATERIALS AND METHODS: Seven independent clinical studies, each involving approximately 100 healthy subjects from a general population, were carried out using a crossover design. In each study, the Oral-B CrossAction toothbrush was compared with an alternative brush for plaque removal efficacy. Plaque was evaluated before and after brushing for 60 s using the Proximal/Marginal Plaque Index. Subjects were randomly assigned to the two brushes in each study and after brushing at visit 1 they returned after a further 2 weeks to repeat the procedure with the second brush. RESULTS: All toothbrushes in the seven studies significantly reduced levels of plaque from their pre-brushing values and were found to be safe with no evidence of oral soft tissue trauma. In each of the studies, the CrossAction was found to be significantly (P < 0.05) more effective than the comparison brush for whole mouth plaque scores, as well as for plaque scores at the gingival margin and proximal surfaces. Advantages in favor of the CrossAction ranged from 9.8% to 23.2% for whole mouth plaque, from 5.3% to 20.6% for the gingival margin and from 12.8% to 24.5% for proximal surfaces. It was concluded that the novel brush head design of the CrossAction toothbrush provides enhanced plaque removal, especially from proximal surfaces, and that this toothbrush is significantly more effective than all seven toothbrushes tested.

A comparative single-use clinical study of the efficacy of two manual toothbrushes with angled bristles.

PURPOSE: To compare the safety and plaque removal efficacy of two angled-bristled toothbrushes. MATERIALS AND METHODS: The brushes were compared using a single-use, cross-over designed study, where healthy subjects from a normal population brushed their teeth with their assigned toothbrush for a timed 60 seconds. Pre- and post-brushing plaque levels were evaluated after disclosing, using the Proximal/Marginal Plaque Index. At the first visit, 100 subjects with a plaque index of > or = 2.20 after 23-25 hours of no oral hygiene were enrolled in the study. At the end of the study, data from 91 subjects were suitable for analysis. The two treatment sequence groups, X-Aktiv/CrossAction and CrossAction/X-Aktiv, were balanced for age and gender and, at each visit, pre-brushing plaque scores did not differ significantly between the two groups. Data from the two visits were pooled, after which plaque removal efficacies were compared. RESULTS: Both toothbrushes were found to be safe and both significantly reduced plaque levels (P< or = 0.0001), but the CrossAction was significantly more effective than the X-Aktiv for whole mouth and marginal sites, as well as the difficult-to-access approximal areas (P< or = 0.0008). For the whole mouth, the CrossAction was 11.8% more effective; for marginal sites the difference was 12.6%, and for approximal sites the difference was 11.4%. It is concluded that the Oral-B CrossAction toothbrush is significantly more effective with respect to plaque removal than the Dr. Best X-Aktiv.

An advanced toothbrush with improved plaque removal efficacy.

PURPOSE: To compare the plaque removal efficacy and safety of a new advanced manual toothbrush, the Oral-B CrossAction, with seven other toothbrushes. MATERIALS AND METHODS: Seven independent, cross-over design clinical studies were conducted using the same examiner who was blind to the identity of the test products and treatment assignments. In each study, approximately 75 healthy adult subjects from a general population brushed with their randomly assigned toothbrush (CrossAction or comparison brush) at Visit 1 for 1 min without supervision or instruction in brushing technique. Subjects returned after a 1-week washout period and brushed with the alternate toothbrush (Visit 2). Plaque was evaluated before and after brushing using the Rustogi Modified Navy Plaque Index. Statistical analyses were conducted by an independent statistician who remained blind to the identity of all test products. RESULTS: Each of the toothbrushes tested provided significant (P < or = 0.0001) reductions in plaque scores after a single brushing. In each of the studies, the CrossAction toothbrush removed significantly (P < or = 0.0001) greater amounts of whole mouth, gingival margin, and approximal plaque than the compared toothbrush. All toothbrushes were found to be safe, with no changes in oral tissues or restorations observed over the course of each study. The results from these studies were consistent, demonstrating that the CrossAction toothbrush significantly enhances the ability of subjects to remove more plaque during normal brushing compared to seven other toothbrushes.

A 3-month comparative investigation of the safety and efficacy of a new toothbrush: results from two independent clinical studies.

PURPOSE: To compare the efficacy of a new toothbrush featuring a novel brush head design with those of two established toothbrushes by measuring plaque and gingivitis over a period of 12 weeks. MATERIALS AND METHODS: The Oral-B CrossAction toothbrush was compared with the Dr. Best InterDent and Crest DeepSweep toothbrushes in two independent, parallel-group, examiner-blind clinical studies. Each study involved approximately 100 healthy individuals from a general population. At baseline, after 23-25 hrs of no oral hygiene, oral hard and soft tissues were examined and whole mouth, marginal and approximal plaque scores and whole mouth gingivitis scores were recorded. Subjects in the two studies were asked to use their assigned toothbrush twice a day. No instruction in brushing technique or brushing time was given. After a period of 6 weeks and finally after 12 weeks, subjects in the studies were reassessed for oral tissue status, and their plaque and gingival indices were rescored. RESULTS: In each of the two studies, the tested toothbrushes significantly reduced levels of plaque and gingivitis. The CrossAction toothbrush was, however, more effective in reducing both plaque and gingivitis over 12 weeks, the differences in favor of the CrossAction being statistically significant. All the toothbrushes tested in this investigation were found to be safe with no evidence of hard or soft tissue trauma.

Endogenous origin of defective retroviruslike particles from a recombinant Chinese hamster ovary cell line.

The presence of budding C-type and intracytoplasmic A-type particles in Chinese hamster ovary (CHO) cells is well documented. However, extensive screening has failed to detect any evidence of infectivity. Continuous-flow ultracentrifugation has been used to concentrate extracellular particles from culture fluid of a recombinant CHO cell subclone for molecular characterization. Particles exhibiting reverse transcriptase activity and associated with mammalian C-type retrovirus structural proteins banded in sucrose gradients at a density characteristic of retroviruses. Examination of gradient-purified particles by electron microscopy revealed morphology and size similar to other retroviruses. Double-gradient-purified particles contained RNA which hybridized to probes for murine leukemia virus, and endogenous Chinese hamster intracisternal A-particle elements. DNA sequence analysis of a cDNA clone isolated from purified particles revealed multiple interruptions of the endonuclease reading frame, providing one possible explanation for the noninfectious nature of the observed particles. Sequences present as RNA in purified particles were also present as conserved, repetitive, provirus sequences in genomic DNA of all CHO cell lines examined and in Chinese hamster liver DNA. The observed particles are therefore likely to be the products of endogenous retroviruslike elements present in the germline of Chinese hamsters.

Defective endogenous retrovirus-like sequences and particles of Chinese hamster ovary cells.

The presence of budding C-type and intracytoplasmic A-type particles in Chinese hamster ovary (CHO) cells is well documented. However, extensive screening has failed to detect any evidence of infectivity. To investigate the origin and expression of these particles, retrovirus-like sequences which are actively transcribed in CHO cells have been cloned and characterized. Two families of sequences related to intracisternal A-particle (IAP) genomes of mice and Syrian hamsters were identified in cytoplasmic RNA from CHO cells (CHO IAP family I and family II). None of the four clones which were sequenced exhibited intact gag, pol, or env open reading frames. Only IAP family II sequences were present in purified extracellular particles of CHO cells. Several cDNA sequences related to mammalian C-type retrovirus genomes were isolated and cloned from gradient-purified, extracellular particles of recombinant CHO cells. All were homologous to the conserved endonuclease domain of murine leukemia virus. Nucleotide sequence analysis of the largest cDNA revealed multiple interruptions of the endonuclease encoding reading frame providing one possible explanation for the non-infectious nature of the particles observed in CHO cells. Both types of retrovirus-like sequences identified in purified extracellular particles of CHO cells (CHO IAP family II and C-type) were present as conserved, moderately repetitive sequences in DNA of all CHO cell lines examined, as well as in DNA from a Chinese hamster liver. It is therefore likely that the extracellular retrovirus-like particles of CHO cells are the products of endogenous provirus elements present in the germline of Chinese hamsters.

Recent studies on retrovirus-like particles in Chinese hamster ovary cells.

Highly concentrated (4000-7000-fold) culture fluids from CHO cells were analysed for the presence of retrovirus-like activity. Concentrates containing reverse transcriptase activity were detected and further purified by sucrose density gradient centrifugation. Particles banding at 1.13-1.16 g/ml were found to contain nucleic acid sequences and structural proteins related to those found in murine and other retroviruses. Analysis of the endonuclease gene has shown no intact open reading frames. Approximately 100-300 copies of the C-type sequences were present in the genome of CHO cell lines as well as in the DNA extracted from Chinese hamster liver, indicating that these sequences are present in the germ line of the species. Concentrates were analysed for infectivity by direct inoculation and co-cultivation with a series of detector cells. No evidence of infectivity was detected by reverse transcriptase, mink cell S+L- focus assay or by electron microscopic analysis of the inoculated detector cells after at least four passages in culture.

Chinese hamster ovary cells contain transcriptionally active full-length type C proviruses.

We have isolated a genomic locus from Chinese hamster ovary (CHO) cells that contains a full-length provirus. Nucleotide sequence analysis indicates that it is a defective member of the rodent type C retrovirus family with an env region that is similar to those of mouse amphotropic retrovirus and subgroup B feline leukemia virus. We were able to demonstrate that this provirus is a member of a closely related family of full-length proviruses in CHO cells and Chinese hamster liver. Hybridization probes generated from this genomic clone were used to characterize type C retrovirus RNA expression in CHO cells. Full-length genomic RNA and subgenomic envelope mRNA were detected in CHO cell lines but not in the human-derived 293 cell line. Interestingly, we discovered that the site of retrovirus integration lies within a G repeat sequence belonging to the short interspersed element family of retroposons.

Presence and transcription of intracisternal A-particle-related sequences in CHO cells.

We have characterized sequences expressed in Chinese hamster ovary (CHO) cells which are related to the intracisternal A-particle (IAP) genes of mice and Syrian hamsters. Several cDNA clones homologous to Syrian hamster IAP probes have been isolated and used to evaluate the abundance and expression of these retroviruslike sequences. DNA blot analysis with homologous Chinese hamster IAP probes revealed that IAP-related sequences are present in CHO cell DNA at moderately repetitive levels (approximately 300 copies per haploid genome). Sequence analysis has revealed the existence of at least two distinct families of IAP-related sequences in CHO cell DNA. Family I sequences exhibit identical 4.5-kilobase-pair internal deletions relative to complete IAP genomes of mice or Syrian hamsters, but family II sequences showed no major sequence discontinuities relative to the IAP genes of other species. Both families are expressed as abundant cytoplasmic RNA in CHO cells, but only family II sequences produce abundant transcripts of a size consistent with that of a full-length IAP RNA. Intact gag, pol, or env open reading frames were not present in sequences of either family, although incomplete open reading frames spanning putative p27 and protease regions of IAP genes were observed.