Modelling the Impact of Vector Control on Lymphatic Filariasis Programs: Current Approaches and Limitations.

Vector control is widely considered an important tool for lymphatic filariasis (LF) elimination but is not usually included in program budgets and has often been secondary to other policy questions in modelling studies. Evidence from the field demonstrates that vector control can have a large impact on program outcomes and even halt transmission entirely, but implementation is expensive. Models of LF have the potential to inform where and when resources should be focused, but often simplify vector dynamics and focus on capturing human prevalence trends, making them comparatively ill-designed for direct analysis of vector control measures. We review the recent modelling literature and present additional results using a well-established model, highlighting areas of agreement between model predictions and field evidence, and discussing the possible determinants of existing disagreements. We conclude that there are likely to be long-term benefits of vector control, both on accelerating programs and preventing resurgence.

Cross-compatibility of methacrylate-based resin composites and etch-and-rinse one-bottle adhesives.

OBJECTIVE: To compare dentin shear bond strength (SBS) of four combinations of light-activated one-bottle adhesives and composites to determine if cross-compatibility exists, and to determine if the use of the same manufacturer's adhesive and composite results in higher SBS than systems that combine different manufacturers' products. METHODS: One hundred sixty human third molars were used for bonding (n=10). Specimens were treated with 37% phosphoric acid and one of four etch-and-rinse adhesives. Specimens were placed in a bonding jig, which was filled with one of four composites. Adhesives PQ1 (Ultradent), Excite (Ivoclar-Vivadent), Optibond Solo Plus (Kerr), and Single Bond (3M-ESPE) and composites Vit-l-Escence (Ultradent), Four Seasons (Ivoclar-Vivadent), Premise (Kerr), and Filtek Supreme Plus (3M-ESPE) were tested. SBS was measured at 24 hours and three months with a testing machine at a speed of 1 mm/min and expressed in MPa. A three-way analysis of variance and Tukey tests were used for data analysis. RESULTS: Significant differences were evidenced among composites for each adhesive system (p<0.001) and among adhesives for each composite system (p<0.001). Optibond Solo Plus and PQ1 yielded significantly higher bond strengths than Single Bond and Excite for all composite systems (p<0.05). All combinations, with the exception of two, demonstrated a decrease in bond strength values after aging. CONCLUSIONS: Cross-compatibility was demonstrated, indicating that etch-and-rinse one-bottle adhesive systems can be safely used with composites from different manufacturers without a compromise to the bond strength. Moreover, even higher mean SBS values were demonstrated for selective combinations of different manufacturers' products

Experimental manufacture of wooden implements with tools of flaked stone.

Several contemporary archeologists recaptutring an almost-lost art by developing skill at knapping (shaping) stone artifacts by pressure and percussion. However, little is known of how these artifacts could be used. We describe three experiments in the carving of wood implments with stone tools alone, and we outline some of the problems of making and applying a do-it- yolur-self lithic tool kit.

Identification of putative parasitism genes expressed in the esophageal gland cells of the soybean cyst nematode Heterodera glycines.

Cloning parasitism genes encoding secretory proteins expressed in the esophageal gland cells is the key to understanding the molecular basis of nematode parasitism of plants. Suppression subtractive hybridization (SSH) with the microaspirated contents from Heterodera glycines esophageal gland cells and intestinal region was used to isolate genes expressed preferentially in the gland cells of parasitic stages. Twenty-three unique cDNA sequences from a SSH cDNA library were identified and hybridized to the genomic DNA of H. glycines in Southern blots. Full-length cDNAs of 21 clones were obtained by screening a gland-cell long-distance polymerase chain reaction cDNA library. Deduced proteins of 10 clones were preceded by a signal peptide for secretion, and PSORT II computer analysis predicted eight proteins as extracellular, one as nuclear, and one as plasmalemma localized. In situ hybridization showed that four of the predicted extracellular clones were expressed specifically in the dorsal gland cell, one in the subventral gland cells, and three in the intestine in H. glycines. The predicted nuclear clone and the plasmalemma-localized clone were expressed in the subventral gland cells and the dorsal gland cell, respectively. SSH is an efficient method for cloning putative parasitism genes encoding esophageal gland cell secretory proteins that may have a role in H. glycines parasitism of soybean.

Signal peptide-selection of cDNA cloned directly from the esophageal gland cells of the soybean cyst nematode Heterodera glycines.

Secretions from the esophageal gland cells of plant-parasitic nematodes play critical roles in the nematode-parasitic cycle. A novel method to isolate cDNA encoding putative nematode secretory proteins was developed that utilizes mRNA for reverse transcription-polymerase chain reaction derived from microaspiration of the esophageal gland cell contents of parasitic stages of the soybean cyst nematode Heterodera glycines. The resulting H. glycines gland cell cDNA was cloned into the pRK18 vector, and plasmid DNA was transformed into a mutated yeast host for specific selection of cDNA inserts that encode proteins with functional signal peptides. Of the 223 cDNA clones recovered from selection in yeast, 97% of the clones encoded a predicted signal peptide. Fourteen unique cDNA clones hybridized to genomic DNA of H. glycines on Southern blots and, among them, nine cDNA clones encoded putative extracellular proteins, as predicted by PSORT II computer analysis. Four cDNA clones hybridized to transcripts within the dorsal esophageal gland cell of parasitic stages of H. glycines, and in situ hybridization within H. glycines was not detected for eight cDNA clones. The protocol provides a direct means to isolate potential plant-parasitic nematode esophageal gland secretory protein genes.

Developmental expression of secretory beta-1,4-endoglucanases in the subventral esophageal glands of Heterodera glycines.

Two beta-1,4-endoglucanases (EGases), Hg-eng-1 and Hg-eng-2, were recently cloned from the soybean cyst nematode, Heterodera glycines, and their expression was shown in the subventral esophageal glands of hatched second-stage juveniles (J2). We examined the expression of these EGases in the subventral glands of all post-embryonic life stages of H. glycines by in situ hybridization and immunolocalization. The first detectable accumulation of EGase mRNAs occurred in the subventral glands of unhatched J2. EGase transcripts remained detectable in J2 after hatching and during subsequent root invasion. However, in late parasitic J2 and third-stage juveniles (J3), the percentage of individuals that showed EGase transcripts decreased. In female fourth-stage juveniles and adult females, EGase transcripts were no longer detected in the subventral glands. EGase hybridization signal reappeared in unhatched males coiled within the J3 cuticle, and transcripts were also present in the subventral glands of migratory adult males. Immunofluorescence labeling showed that EGase translation products are most abundantly present in the subventral glands of preparasitic J2, migratory parasitic J2, and adult males. The presence of EGases predominantly in the migratory stages suggests that the enzymes are used by the nematodes to soften the walls of root cells during penetration and intracellular migration.

Secretory granule proteins from the subventral esophageal glands of the potato cyst nematode identified by monoclonal antibodies to a protein fraction from second-stage juveniles.

Sodium dodecyl sulfate-extracted proteins from second-stage juveniles (J2) of the potato cyst nematode Globodera rostochiensis were fractionated by preparative continuous flow electrophoresis, and monoclonal antibodies (MAbs) were raised against the 38- to 40.5-kDa protein fraction. Screening of the hybridoma culture fluids by immunofluorescence microscopy of J2 resulted in the identification of 12 MAbs that bound specifically to the subventral esophageal glands. On Western blots of J2 these MAbs identified four protein bands with apparent molecular masses of 30, 31, 39, and 49 kDa. Immunoelectron microscopy with one of these MAbs showed an intense labeling of the electron dense core of the secretory granules in the subventral gland cells of J2. It is concluded that one or more of these proteins are localized within these secretory granules. Immunofluorescence microscopy of J2 from other plant parasitic nematode species showed that most of these MAbs also bind to the subventral glands of G. pallida and G. tabacum but not of Heterodera schachtii, H. glycines, Meloidogyne incognita, or M. hapla.

Molecular characterisation and expression of two venom allergen-like protein genes in Heterodera glycines.

Secretory proteins encoded by genes expressed in the oesophageal gland cells of plant-parasitic nematodes have key roles in nematode parasitism of plants. Two venom allergen-like protein cDNAs (designated hg-vap-1 and hg-vap-2)were isolated from Heterodera glycines gland cell cDNA libraries. Both cDNAs hybridised to genomic DNA of H. glycines in Southern blots. The hg-vap-1 cDNA contained an open reading frame encoding 215 amino acids with the first 25 amino acids being a putative secretion signal. The hg-vap-2 cDNA contained an open reading frame encoding 212 amino acids with the first 19 amino acids being a putative secretion signal. Genes of hg-vap-1 and hg-vap-2 contained four introns, which ranged in size from 44 to 574 bp, and five exons ranging in size from 43 to 279 bp. In situ hybridisation analyses showed that mRNAs of both vap genes accumulated specifically in the subventral gland cells of H. glycines during parasitism. The gland cell-specific expression and presence of predicted secretion signal peptides in both VAPs suggest that these proteins are secreted from the nematode and may play a role in the infection of host plants by this parasite.

Survey of ethical issues in dental research.

The American Association for Dental Research (AADR) surveyed its leaders to determine their perceptions of the prevalence of problematic research practices and the possible roles AADR should play in promoting scientific integrity. Seventy-six of the 98 program chairs and Association officers (1990-1995) surveyed responded. In general, these respondents did not think that serious misconduct or sloppy science occurred more often in AADR than in other scientific disciplines. Overall, respondents rated practices that undermine the trustworthiness of science (falsifying or fabrication of research data, retaliation, failure to present negative results, failure to disclose involvement with commercial enterprises, failure to maintain research records, etc.) as more serious, but less prevalent, than practices considered disrespectful of the work of others (gift authorship, citing sources without reading them, dividing a project into many small units, etc.). All respondents said that they had observed each of the less serious problematic practices one or more times, whereas 10% reported having observed retaliation, 30% reported having observed falsification, and 54% reported having observed plagiarism one or more times. AADR leaders had observed many more instances of misconduct and other problematic research practices than had faculty surveyed by Swazey et al. (1993), supporting conclusions by Greenberg and Goldberg (1994) that status and years of experience are associated with more frequent observations of misconduct. With respect to the possible roles the AADR might play in promoting research integrity, 88% thought that AADR should develop ethics cases and materials for educational use, 78% thought that AADR should create a process for addressing allegations of misconduct, 72% thought that the Association should develop an ethics committee or consultation service, 55% thought it should create a yearly ethics symposium, and 45% thought that the AADR should develop a more specific code of ethics to complement the general code recently developed by the IADR.

Effect of a social cognitive intervention on oral health status, behavior reports, and cognitions.

An intervention designed to test the influence of cognitive restructuring on protective oral health behaviors was conducted with 108 patients with mild to moderate gingivitis. Subjects in the experimental group viewed slides of active, mobile bacteria taken from their mouths on 5 occasions: before and after prophylaxis and at 3 appointments, one month apart. A specially trained hygienist discussed with these participants the process of periodontal disease, the role of bacteria, and self-efficacy (self-control) for oral hygiene self-care. Both experimental and control group subjects received instruction in oral self-care procedures. Assessments of oral health using Löe and Silness' plaque and gingival indices (PI and GI) were taken throughout the study and at 3- and 6-month follow-up visits. Self-efficacy, oral hygiene intentions, attitudes, and values comprised the set of cognition variables. Plaque and gingival indices mean differences between groups approached significance at visit 6. Analyses were also performed using percent of gingival surfaces scored at "0" (no visible bleeding on probing). A trend occurred for group differences in percent "0" scores at visit 6, with the experimental group maintaining higher percent zeros (better health) at this 3-month follow-up. At visit 7 (9-month follow-up), PI and GI differences disappeared. No significant differences were found between groups for oral health cognitions or behavior reports over time. The data suggest that the cognitive-behavioral intervention produced a delayed relapse in protective oral self-care behaviors, and by extension, oral health status. Such a delay could be clinically relevant in promoting adherence to oral hygiene behavior between professional visits.

The effect of storage on Guthrie cards: implications for deoxyribonucleic acid amplification.

The effect of storage on (1) amplifiability of nucleic acid (present at low level) and (2) properties of whole blood polymerase chain reaction (PCR) inhibitors (present at high levels) in Guthrie card bloodspots was evaluated. Natural PCR inhibitors (protein, hemoglobin, iron) were selectively eluted from Guthrie cards (1 to 30 mo storage) under nondenaturing conditions and quantitated. The PCR was performed by direct amplification. It was found that PCR inhibitors become increasingly resistant to elution ("fixed") over time. For example, 600 micrograms protein, 1.87 au hemoglobin, and 374 ng iron were solubilized from 1 mo bloodspots. In contrast, only 137 micrograms protein (22 percent), 0.34 au hemoglobin (18 percent), and 147 ng iron (39 percent) were solubilized from 30 mo bloodspots. Fixation does not result from excessive desiccation since bloodspot weight 2.20 mg +/- 0.21 (1 mo) and 1.92 mg +/- 0.31 (30 mo) was not significantly changed (p > 0.05). The majority of protein was characterized as albumin, and two rbc metal-containing proteins, carbonic anhydrase and hemoglobin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Despite the presence of "fixed" PCR inhibitors, it was found that bloodspots stored 1 to 30 mo could be amplified for two regions (98 bp and 491 bp amplicons) encoding the delta F508 cystic fibrosis mutation. It is suggested that nucleic acid also becomes "fixed" to the filter paper matrix and accounts, in part, for the ability to amplify Guthrie cards by direct PCR and low yield of deoxyribonucleic acid (DNA) reported for microextraction methods.

Detection of cystic fibrosis delta F508 mutation by anti-double-stranded DNA antibody.

This study evaluated an enzyme immunoassay (EIA) as a screening tool for detection of the most common mutation (delta F508) in cystic fibrosis (CF). Guthrie card bloodspots were extracted to remove whole blood polymerase chain reaction (PCR) inhibitors. The washed filter paper was directly amplified under standard (98 bp amplicons) or modified PCR conditions (491 bp amplicons) for the delta F508 mutation. Monoclonal anti-double stranded deoxyribonucleic acid antibody was used to detect competent hybrid formation between PCR products and normal (N) and mutant (M) cDNA (deoxyribonucleic acid) probes coated to microtiter plate wells. Under standard conditions, mean relative color production (N/M) via an enzyme-linked horseradish peroxidase secondary antibody was 8.8, 0.6 and 0.04 for individuals normal, heterozygous and homozygous for the CF delta F508 mutation, respectively (n = 27). Comparison of EIA results to those obtained by tris-borate-EDTA/8 percent polyacrylamide gel electrophoresis (TBE-PAGE) yielded excellent correlation (100 percent) for all three genotypes (n = 27). In comparison to TBE-PAGE, the EIA was 5 to 10 fold more sensitive when serially diluted PCR samples were evaluated. Larger PCR products (491 bp amplicons) for the CF delta F508 mutation obtained under modified conditions were not resolved by TBE-PAGE. The EIA, however, demonstrated equal sensitivity to the 98 bp and 491 bp amplicons. Performance time for TBE-PAGE analysis was substantially shorter (25 percent) than the EIA (3.5 to 4 h and 4.5 to 5 h, respectively) when small batches of samples (n = 5) were analyzed. The TBE-PAGE was not, however, convenient for screening large numbers of PCR-amplified samples (n > 15).

Polymerase chain reaction amplification of Guthrie card deoxyribonucleic acid: extraction of nucleic acid from filter matrices.

This study evaluated two deoxyribonucleic acid (DNA) extraction methods for Guthrie card bloodspots. Our water-based extraction technique was compared with a commercial kit (GFX extraction system). In contrast to our nondenaturing method, the GFX system utilizes chaotropes to extract DNA. Extracted DNA is subsequently purified by selective elution from a glass fiber matrix. To evaluate DNA extraction, polymerase chain reaction (PCR) for a 491 bp region encoding the cystic fibrosis delta F508 mutation was performed and PCR products electrophoresed on polyacrylamide gels and stained with ethidium bromide. Amplification of GFX-extracted DNA required low sample volume (1 to 5 microL) indicating the presence of residual PCR inhibitors. The GFX volumes (1/20 to 1/4 punch) were comparable to our standard conditions and represented 0.16-0.80 microL whole blood (20 to 40 ng DNA). The GFX-extracted DNA was found to be stable (6 mo, -15 degrees C). Performance time for the GFX method was less than our standard water-based extraction (about 30 min), but more costly. The GFX extraction kit was adaptable for limited sample (i.e., extraction of a 3 mm punch yields 20 amplifications). The GFX extraction kit provides a useful means to standardize Guthrie card DNA extraction.

Dentin bonding agents and the smear layer.

The morphology and treatment of the smear layer are discussed. Also included are a review of dentin bonding agent classification and chemistry, and a summary of recent bond strength research results. Finally, the current status of dentin bonding agents is discussed.

Rubber dam usage among practicing dentists.

This study reports on a survey administered to graduates of the State University of New York at Buffalo School of Dental Medicine concerning usage of and attitudes toward the rubber dam. Differences in both reported usage and attitudes were found between graduates who had received minimal rubber dam training and those who had received more intensive training. Those with graduate training reported more frequent use of the dam than those with no graduate training; however, overall reported usage of the rubber dam was quite low. Comments provided by some respondents suggest that in the educational process a greater emphasis should be put on the reasons for using the dam rather than placement technique.

Microleakage in various dentin bonding agent/composite resin systems.

One important consideration in the selection of a dentin bonding agent/composite resin system is its resistance to marginal leakage. The purpose of this study was to compare both the extent and the pathways of marginal leakage for four currently available dentin bonding agent/composite resin systems. Class 5 restorations were placed in the buccal and lingual surfaces of 20 extracted human teeth. Specimens were subjected to thermal stress before being placed in silver nitrate solution. They were then sectioned longitudinally and observed under a light microscope. Selected samples were further studied using scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDX). Different systems exhibited different leakage patterns. Findings suggest that the smear layer should be either conditioned or removed prior to dentin bonding agent application to provide optimal resistance to microleakage.

Effect of dentinal pretreatment on bond strength between glass-ionomer cement and dentin.

Removal of the dentinal smear layer prior to placement of glass-ionomer cement is thought to maximize the strength of glass-ionomer cement/dentin bonding. This study evaluated the effect of three polyacrylic acid pretreatments on bond shear strength between glass-ionomer cement and dentin. Extracted human molars were divided into four groups of 30 specimens each. One group (the control) received no pretreatment. Specimens in the remaining groups were pretreated with one of three commercially available polyacrylic acid conditioners, used according to the manufacturers' recommendations. The results indicated significant differences in shear strength among pretreatment conditions. Since the manufacturers' recommendations varied, it is not clear if these results were due to differences in polyacrylic acid concentration or to other factors, such as application time or placement procedure.

Leakage patterns associated with glass-ionomer-based resin restorations.

This study compared microleakage patterns for glass-ionomer-cement-based resin systems with and without a separating agent placed between the glass ionomer and resin. Results indicated significant leakage (100%) at the dentin glass-ionomer interface for specimens without a separating agent. Those with a separating agent showed almost no leakage between the dentin and glass ionomer (10%) and some leakage at the resin/glass ionomer interface (40%). These results suggest that the forces of polymerization shrinkage are stronger than the chemical bond between glass-ionomer cement and dentin. This bond fails during resin polymerization, eliminating any supplementary retention gained through chemical adhesion to dentin and opening a pathway for microleakage.

Systemic necrotizing vasculitis in nine young beagles.

A systemic necrotizing vasculitis of unknown etiopathogenesis may be termed juvenile polyarteritis syndrome (JPS). The syndrome has been recognized primarily in young Beagles used for toxicologic studies. We studied 9 young Beagles with JPS. Affected dogs had fever (40 to 41.5 C), anorexia, and signs of pain in the cervical area. They had a characteristic hunched stance, and were unwilling to move. Laboratory abnormalities in all dogs included nonregenerative anemia, hypoalbuminemia, and leukocytosis characterized by a mature neutrophilia. Analysis of CSF revealed a moderate to severe neutrophilic pleocytosis and a mildly high protein concentration in most dogs. Signs of disease resolved rapidly with high doses (2.2 mg/kg of body weight, PO) of prednisone. If untreated, clinical signs and laboratory abnormalities had a remitting and relapsing course in most dogs. Findings at necropsy included necrotizing arteritis with fibrinoid necrosis, periarteritis, thrombosis, and intimal proliferation that most frequently affected small- to medium-sized vessels in the cervical spinal cord, mediastinum, and heart. An immune-mediated pathogenesis for this disease is suspected.