Finding PRRSV in sow herds: Family oral fluids vs. serum samples from due-to-wean pigs.

The aim of this study was to compare the detection of porcine reproductive and respiratory syndrome virus (PRRSV) in due-to-wean litters in commercial swine breeding herds using family oral fluids (FOF) vs. individual piglet serum samples. FOF and piglet serum samples were collected in 199 due-to-wean litters on six farms containing 2177 piglets. All samples were individually tested for PRRSV RNA by RT-rtPCR. A litter was considered PRRSV-positive when PRRSV RNA was detected in ≥ 1 piglet serum sample or the FOF sample. Mixed effect logistic regression with farm as a random effect was used 1) to evaluate the probability of obtaining a PRRSV RNA positive FOF as a function of the proportion of viremic piglets in a litter and 2) the effect of litter size and parity on the probability that a litter would test PRRSV RNA positive in FOF. A Bayesian prevalence estimation under misclassification (BayesPEM) analysis was used to calculate the PRRSV prevalence and 95 % credible interval given the condition that all samples (FOF and serum) tested negative. In total, 34 of 199 litters (17.1 %) contained ≥ 1 viremic piglet(s), and 28 of 199 litters (14.1 %) were FOF positive. When all piglet serum samples within a litter tested negative, 1 of 165 FOF (0.6 %) tested PRRSV RNA positive. The probability of a PCR-positive FOF sample from litters with 10 %, 20 %, 30 %, 40 %, and 50 % within-litter PRRSV prevalence was 3.5 %, 35.1 %, 88.8 %, 99.2 %, and >99.9 %, respectively. The odds of a PCR-positive FOF in a first parity litter were 3.36 times (95 % CI: 2.10-5.38) that of a parity ≥ 2 litter. The odds of a positive FOF result in a litter with ≤ 11 piglets were 9.90 times (95 % CI: 4.62-21.22) that of a litter with > 11 piglets. FOF was shown to be an efficacious sample type for PRRSV detection in farrowing rooms. A risk-based approach for litter selection combined with FOF collection can be used to improve on-farm PRRSV detection with a limited sample size, compared to sampling multiple individual pigs. Finally, the BayesPEM analysis showed that PRRSV may still be present in breeding herds when all samples (serum and FOF) test PRRSV RNA negative, i.e., negative surveillance results should be interpreted with caution.

Collecting oral fluid samples from due-to-wean litters.

Oral fluids are a common diagnostic sample in group-housed nursery, grow-finish, and adult swine. Although oral fluids from due-to-wean litters could be a valuable tool in monitoring pathogens and predicting the health status of pig populations post-weaning, it is generally not done because of inconsistent success in sample collection. The objective of this study was to determine the optimum procedure for collecting oral fluid samples from due-to-wean litters. Successful collection of oral fluids from due-to-wean litters using "Litter Oral Fluid" (LOF) or "Family Oral Fluid" (FOF) sampling techniques were compared in 4 phases involving 920 attempts to collect oral fluids. Phase 1 testing showed that prior exposure to a rope improved the success rates of both LOF (33.4%) and FOF (16.4%) techniques. Phase 2 determined that longer access to the rope (4 h vs 30 min) did not improve the success rate for either LOF or FOF. Phase 3 evaluated the effect of attractants and found that one (Baby Pig Restart®) improved the success rate when used with the FOF technique. Phase 4 compared the success rates of "optimized LOF" (litters previously trained) vs "optimized FOF" (litter previously trained and rope treated with Baby Pig Restart®) vs standard FOF. No difference was found between the FOF-based techniques, but both were superior to the "optimized LOF" technique. Thus, FOF-based procedures provided a significantly higher probability of collecting oral fluids from due-to-wean litters (mean success rate 84.9%, range 70% to 92%) when compared to LOF-based methods (mean success rate 24.1%, range 16.5% to 32.2%).

Parental attitudes on restorative materials as factors influencing current use in pediatric dentistry.

PURPOSE: The purpose of this study was to determine pediatric dentists' current practices and the perceptions about parents' opinions and how those parental preferences regarding dental materials influence dentists' practices. METHODS: A questionnaire was sent to 500 randomly selected active members of the American Academy of Pediatric Dentistry. Twenty-five items queried demographics, use of restorative materials, perceptions of parents' attitudes towards materials, and dentists' reactions to parents' concerns. RESULTS: The survey response rate was 61%. Parental concerns about materials in decreasing order were: (1) esthetics; (2) cost; (3) toxicity; and (4) durability. Parents' greatest concerns about stainless steel crowns were: (1) esthetics; and (2) cost. Among respondents, 43% followed parental preferences when challenged, and 28% currently never use amalgam. Amalgam use and the dentists' perception of parental challenge were each related to the socioeconomic status of the practice population, with lower socioeconomic practices feeling less parental challenge than higher socioeconomic practices and being more likely to use amalgam than "white" filling materials (P = .001). CONCLUSIONS: Mercury concerns occur more frequently with higher than lower socioeconomic status parents (P = .002). Stainless steel crowns are challenged based on esthetics and cost. When confronted, many pediatric dentists (43%) follow parental preferences, even when that action is contrary to their initial clinical judgment.

Coupled whispering gallery mode resonators in the Terahertz frequency range.

We report on coupling of two whispering gallery mode resonators in the Terahertz frequency range. Due to the long wavelength in the millimeter to submillimeter range, the resonators can be macroscopic allowing for accurate size and shape control. This is necessary to couple specific modes of two or more resonators. Sets of polyethylene (PE) and quartz disk resonators are demonstrated, with medium (loaded) quality (Q)-factors of 40-800. Both exhibit coinciding resonance frequency spectra over more than ten times the free spectral range. Loading effects of single resonators are investigated which provide strong Q-factor degradation and red-shifts of the resonances in the 0.2% range. By coupling two resonators of the same size, we observe mode splitting, in very good agreement with our numerical calculations.

Assessment of abattoir based monitoring of PRRSV using oral fluids.

Various porcine reproductive and respiratory syndrome virus (PRRSV) regional elimination projects have been implemented in the U.S., but none have yet succeeded. In part, this reflects the need for efficient methods to monitor over time the progress of PRRSV status of participating herds. This study assessed the feasibility of monitoring PRRSV using oral fluids collected at the abattoir. A total of 36 pig lots were included in the study. On-farm oral fluid (n = 10) and serum (n = 10) collected within two days of shipment to the abattoir were used to establish the reference PRRSV status of the population. Oral fluids (n = 3 per lot) were successfully collected from 32 lots (89%) at the lairage. Three veterinary diagnostic laboratories (VDLs) tested the sera (VDL1 and VDL3: n = 316, VDL2: n = 315) and oral fluids (VDL1 and VDL3: n = 319, VDL2: n = 320) for PRRSV antibodies (ELISA) and RNA (rRT-PCR). Environmental samples (n = 64, 32 before and 32 after pigs were placed in lairage) were tested for PRRSV RNA at one VDL. All oral fluids (farm and abattoir) tested positive for PRRSV antibody at all VDLs. PRRSV positivity frequency on serum ranged from 92.4% to 94.6% among VDLs, with an overall agreement of 97.6%. RNA was detected on 1.3% to 1.9%, 8.1% to 17.7%, and 8.3% to 17.7% of sera, on-farm and abattoir oral fluids, respectively. Between-VDLs rRT-PCR agreement on sera and oral fluids (farm and abattoir) ranged from 97.8% to 99.0%, and 79.0% to 81.2%, respectively. Between-locations agreement of oral fluids varied from 31.3% to 50% depending on the VDL. This study reported the application of swine oral fluids collected at the abattoir for monitoring PRRSV, and describes the between-VDL agreement for PRRS testing of serum and oral fluid field samples.

Use of Oral Fluids for Detection of Virus and Antibodies in Pigs Infected with Swine Vesicular Disease Virus.

The use of swine oral fluid (OF) for the detection of nucleic acids and antibodies is gaining significant popularity. Assays have been developed for this purpose for endemic and foreign animal diseases of swine. Here, we report the use of OF for the detection of virus and antibodies in pigs experimentally infected with swine vesicular disease virus (SVDV), a virus that causes a disease clinically indistinguishable from the economically devastating foot-and-mouth disease. Viral genome was detected in OF by real-time reverse transcription polymerase chain reaction (RRT-PCR) from 1 day post-infection (DPI) to 21 DPI. Virus isolation from OF was also successful at 1-5 DPI. An adapted competitive ELISA based on the monoclonal antibodies 5B7 detected antibodies to SVDV in OF starting at DPI 6. Additionally, using isotype-specific indirect ELISAs, SVDV-specific IgM and IgA were evaluated in OF. IgM response started at DPI 6, peaking at DPI 7 or 14 and declining sharply at DPI 21, while IgA response started at DPI 7, peaked at DPI 14 and remained high until the end of the experiment. These results confirm the potential use of OF for SVD surveillance using both established and partially validated assays in this study.

Inositol 1,4,5-trisphosphate receptor expression in odontoblast cells.

The cellular distribution of inositol 1,4,5-trisphosphate receptors was examined in rodent maxillary incisor teeth. In situ hybridization studies with a transmembrane probe of type I inositol 1,4,5-trisphosphate receptor indicated that this receptor/channel was highly expressed in odontoblast cells of incisor teeth. In contrast, very low labeling was observed in dental pulp. Northern analysis showed a message size of approximately 9.5 kilobases for this receptor, and demonstrated that type III inositol 1,4,5-trisphosphate receptor was expressed in incisor teeth. Immunocytochemical studies confirmed that types I and III inositol 1,4,5-trisphosphate receptors were both highly expressed in odontoblasts while very low expression was detected in dental pulp. Finally, antibodies that recognized alpha subunits of the Gq class of GTP binding proteins also stained odontoblasts. These results indicate that receptor-mediated regulation of calcium release through inositol 1,4,5-trisphosphate receptors may occur in odontoblasts of rat incisor teeth. These findings also suggest that inositol 1,4,5-trisphosphate receptor/channels regulate calcium flux in odontoblasts during mineralization of dentin, or in growth and differentiation of incisor tissue.

Comparison of specimens for detection of porcine reproductive and respiratory syndrome virus infection in boar studs.

Porcine reproductive and respiratory syndrome virus (PRRSV)-contaminated semen from boars is a route of transmission to females, and early detection of PRRSV infection in boars is a key component in sow farm biosecurity. The purpose of this study was to determine the optimum diagnostic specimen(s) for the detection of acute PRRSV infection in boars. Individually housed boars (n = 15) were trained for semen and oral fluid collection and then vaccinated with a commercial PRRSV modified live virus vaccine. Starting on the day of vaccination and for 14 days thereafter, oral fluid specimens were collected daily from all boars. The 15 boars were subdivided into three groups of 5, and serum, blood swabs and 'frothy saliva' were collected at the time of semen collection on a 3-day rotation. Frothy saliva, derived from the submandibular salivary gland, is produced by aroused boars. Semen was centrifuged, and semen supernatant and cell fractions were tested separately. All samples were randomly ordered and then tested by PRRSV real-time quantitative reverse-transcription polymerase chain reaction assay (rRT-PCR) and PRRSV antibody ELISA. In this study, a comparison of serum, blood swab, and oral fluid rRT-PCR results found no statistically significant differences in the onset of detection or proportion of positives, but serum was numerically superior to oral fluids for early detection. Serum and oral fluid provided identical rRT-PCR results at ≥ 5 day post-vaccination. Likewise, the onset of detection of PRRSV antibody in serum, oral fluid and frothy saliva was statistically equivalent, with serum results again showing a numerical advantage. These results showed that the highest assurance of providing PRRSV-negative semen to sow farms should be based on rRT-PCR testing of serum collected at the time of semen collection. This approach can be augmented with oral fluid sampling from a random selection of uncollected boars to provide for statistically valid surveillance of the boar stud.

Pirmenol kinetics and effective oral dose.

The oral form of pirmenol has not been administered to man. Pirmenol was given by mouth to eight patients with chronic, stable premature ventricular beats (PVBs) to determine effective dose and kinetics. The patients were evaluated with a dose-ranging protocol following by a double-blind, crossover, placebo-controlled study of doses that were effective during dose ranging. Oral doses of 150 to 250 mg induced at least 90% suppression of PVBs 18 of the 19 times they were administered during both protocols. During the double blind experiment, a single oral dose of pirmenol suppressed 95 +/- 8% PVBs/hr (mean +/- SD) for 3 consecutive hr, while placebo suppressed 4 +/- 42% PVBs/hr (P less than 0.01). a 90% or greater reduction in PVBs persisted for a median of 6 hr (range 1 to 8 hr). The range of plasma pirmenol concentrations associated with an at last 90% reduction in PVBs was 0.7 to 2.0 micrograms/ml. Median half-life (t1/2) was 9.3 hr (range 6.0 to 12.4) with 86.6 +/- 2.4% protein binding and 82.6 +/- 23.6% bioavailability. At peak drug level there was lengthening of the QTc interval (0.036 sec, P less than 0.05), but no change in heart rate, blood pressure, PR interval or QRS duration, or symptoms. In this single-dose study, pirmenol effectively reduced PVBs, has a relatively long t1/2, and was minimally toxic.

The determination of equilibrium constants for heterogeneous macromolecular interactions.

A method has been developed to determine the association constant for a heterogeneous association of the type A + B in equilibrium AB. This method requires knowledge of the two initial concentrations and of the resulting weight-average molecular weight for each data point. Computer simulations using Gaussian-distributed error on the measured parameters show that the researcher can readily determine whether the particular concentration range chosen is appropriate for the strength of binding and therefore how reliable the calculated constant might be. It is also shown that errors in measuring molecular weight have, in general, a more profound effect than do errors in concentration.

Porcine reproductive and respiratory syndrome virus: routes of excretion.

This study was conducted to delineate potential sites of exit and duration of shedding of porcine reproductive and respiratory syndrome virus (PRRSV). Two experiments of 6 pigs each were conducted. Pigs were farrowed in isolation, weaned at 7 days of age, and housed in individual HEPA filtered isolation chambers. In each experiment, 3 pigs served as controls and 3 were inoculated intranasally with PRRSV (ATCC VR-2402) at 3 weeks of age. In a first experiment, on days 7, 14, 21, 28, 35, and 42 post-inoculation (p.i.), pigs were anesthetized and intubated. The following samples were collected: serum, saliva, conjunctival swabs, urine by cystocentesis, and feces. Upon recovery from anesthesia, the endotracheal tube was removed, rinsed, and the rinse retained. In the second experiment, the sampling schedule was expanded and serum, saliva, and oropharyngeal samples were collected from day 55 to day 124 p.i. at 14 day intervals. Virus was isolated in porcine alveolar macrophages up to day 14 from urine, day 21 from serum, day 35 from endotracheal tube rinse, day 42 from saliva, and day 84 from oropharyngeal samples. No virus was recovered from conjunctival swabs, fecal samples, or negative control samples. This is the first report of isolation of PRRSV from saliva. Virus-contaminated saliva, especially when considered in the context of social dominance behavior among pigs, may plan an important role in PRRSV transmission. These results support previous reports of persistent infection with PRRSV with prolonged recovery of virus from tonsils of swine.

Computers in dentistry.

Traditionally, each professional school has developed its own course or department of health care informatics. We may find it more efficient and productive to establish a department of Medical Informatics to serve all health science colleges. Therefore the initial costs would be reduced and the common knowledge bank would be greatly increased. In a position paper written for the Association of Academic Health Centers lies the detailed plans for the establishment of an integrated health sciences center computer resource. The inclusion of computer courses in the curriculum can be summarized in the following action step. The chief administrative officer of the academic health center should facilitate the work of the deans of the schools of the health professions in convening faculty task forces that will address the introduction of computer literacy and computer applications in health care to the curricula. Although dental informatics is still in its infancy, we must lay a solid foundation for the controlled growth and development of this field of dental science. The problems encountered in developing a course in dental informatics are not unique to this one area. All specialties of health care are grappling with the questions posed by medical informaticians. Although each specialty has its own needs and requirements, the basic underlying principles of medical informatics remains the same. The knowledge we can gain by the exchange of experiences between all fields can greatly increase the speed and accuracy of development. The primary goal of computer literacy in dental education should be to prepare our students for the changing practice environment of the future.

Study of computer applications in dental practice.

The results of this study indicated that some new patterns are emerging in computer usage by dentists. The majority in this study reported utilizing micro- and minicomputers rather than commercial services. The increasing acceptance of personal computers and their decreasing costs will certainly contribute to increased utilization and the development of additional applications.

The electronic window to the world.

Computer networking is a fundamental change in communication technology that carries with it the same significance as the development of human language. The discovery of new tools adds to the human experience, but the ability to communicate and share that knowledge and wisdom results in a factorial increase in the collective wisdom of a global community. This paper presents a brief history and overview of the Internet and then discusses how network application tools can be used in dentistry. Examples of various implementations will be given and a brief discussion of some constraints to implementation of network technology is also included.

[Rubber-band ligation of esophageal and cardiac varices].

Esophageal sclerotherapy was the treatment of choice for bleeding esophageal varices in the past decade. It is effective for treating acute variceal bleeding, as well as eradicating esophageal varices for secondary prevention of bleeding. However, in more than 20% of patients sclerotherapy involves complications, some of which are serious. The high complication rate suggested the development of a new method that should be at least as effective and as easy to perform as sclerotherapy, but with fewer complications and side-effects. Endoscopic variceal ligation was developed at the University of Colorado and described in 1986. It is reported to control active variceal bleeding in about 90% of patients, and to eradicate varices in about 80% of surviving patients. Complications are rare. We have adapted the method in our unit and here describe out preliminary experience in 11 patients.

Growth of the Internet and its impact on health care and society.

The discovery of new tools adds to the human experience, but our newfound ability to communicate and share knowledge and wisdom almost instantaneously results in a factorial increase in the collective wisdom of a global community. Computer networks continue to expand and reach into every corner of the globe. This global information network has the potential to affect many aspects of society. This paper presents a brief history and overview of the Internet and network application tools and discusses some of the ethical issues that need to be addressed as the Internet grows to touch every part of our lives.