Cognitive processing speed in multiple sclerosis clinical practice: association with patient-reported outcomes, employment and magnetic resonance imaging metrics.

BACKGROUND AND PURPOSE: To analyze the relationship between cognitive processing speed, patient-reported outcome measures (PROMs), employment and magnetic resonance imaging (MRI) metrics in a large multiple sclerosis cohort. METHODS: Cross-sectional clinical data, PROMs, employment and MRI studies within 90 days of completion of the Processing Speed Test (PST), a technology-enabled adaptation of the Symbol Digit Modalities Test, were collected. MRI was analyzed using semi-automated methods. Correlations of PST score with PROMs and MRI metrics were examined using Spearman's rho. Wilcoxon rank sum testing compared MRI metrics across PST score quartiles and linear regression models identified predictors of PST performance. Effects of employment and depression were also investigated. RESULTS: In 721 patients (mean age 47.6 ± 11.4 years), PST scores were significantly correlated with all MRI metrics, including cord atrophy and deep gray matter volumes. Linear regression demonstrated self-reported physical disability, cognitive function, fatigue and social domains (adjusted R2  = 0.44, P < 0.001) as the strongest clinical predictors of PST score, whereas that of MRI variables included T2 lesion volume, whole-brain fraction and cord atrophy (adjusted R2  = 0.42, P < 0.001). An inclusive model identified T2 lesion volume, whole-brain fraction, self-reported upper extremity function, cognition and social participation as the strongest predictors of PST score (adjusted R2  = 0.51, P < 0.001). There was significant effect modification by depression on the relationship between self-reported cognition and PST performance. Employment status was associated with PST scores independent of age and physical disability. CONCLUSION: The PST score correlates with PROMs, MRI measures of focal and diffuse brain injury, and employment. The PST score is a feasible and meaningful measure for routine multiple sclerosis care.

Multiple Sclerosis Performance Test: validation of self-administered neuroperformance modules.

BACKGROUND AND PURPOSE: The purpose was to determine the test-retest reliability, practice effects, convergent validity and sensitivity to multiple sclerosis (MS) disability of neuroperformance subtests from the patient self-administered Multiple Sclerosis Performance Test (MSPT) designed to assess low contrast vision (Contrast Sensitivity Test, CST), upper extremity motor function (Manual Dexterity Test, MDT) and lower extremity motor function (Walking Speed Test, WST) and to introduce the concept of regression-based norms to aid clinical interpretation of performance scores using the MSPT cognition test (Processing Speed Test, PST) as an example. METHODS: Substudy 1 assessed test-retest reliability, practice effects and convergent validity of the CST, MDT and WST in 30 MS patients and 30 healthy controls. Substudy 2 examined sensitivity to MS disability in over 600 MS patients as part of their routine clinic assessment. Substudy 3 compared performance on the PST in research volunteers and clinical samples. RESULTS: The CST, MDT and WST were shown to be reliable, valid and sensitive to MS outcomes. Performance was comparable to technician-administered testing. PST performance was poorer in the clinical sample compared with the research volunteer sample. CONCLUSIONS: The self-administered MSPT neuroperformance modules produce reliable, objective metrics that can be used in clinical practice and support outcomes research. Published studies which require patient voluntary consent may underestimate the rate of cognitive dysfunction observed in a clinical setting.

Cloning and characterization of a gene encoding extracellular metalloprotease from Streptomyces lividans.

The prt gene, encoding a protease (Prt) from Streptomyces lividans TK24, was cloned and sequenced. An S. lividans host with plasmid-borne prt secreted 200 micrograms/ml of a 22-kDa Prt into the culture medium. Prt is classified as a metalloprotease since its activity is significantly inhibited by 1,10-phenanthroline or EDTA. The region upstream from prt codes for an incomplete open reading frame (ORF) oriented opposite to prt. This ORF has a strong similarity to a gene family (lysR) whose members regulate the transcription of structural genes required for either biosynthesis or degradation.

A randomized trial of three iron dextran infusion methods for anemia in EPO-treated dialysis patients.

Forty-three hemodialysis patients receiving recombinant erythropoietin (rHuEPO, epoietin alpha) were randomized to receive intravenous iron dextran as a total-dose infusion, 500-mg infusion to total dose, or 100-mg bolus to total dose, in each case during the dialysis procedure. The dose of iron dextran was calculated from the patient's existing hemoglobin to achieve a desired hemoglobin. Patients were eligible to receive intravenous iron dextran if they had a serum ferritin of < or = 100 ng/mL or a serum ferritin of 100 to 200 ng/mL, along with a transferrin saturation of < or = 19%. Patients were excluded if they had prior therapy with iron dextran, aluminum intoxication, or transfusion during the study. The time to the maximum hemoglobin, acute adverse reactions, and delayed adverse reactions were analyzed statistically, and no differences were seen in any of the three groups. Total-dose intravenous iron dextran infusion is safe, convenient, less expensive, and as efficacious as divided-dose infusions.

Acute effects of bilateral lung volume reduction surgery on lung and chest wall mechanical properties.

STUDY OBJECTIVES: To characterize acute changes in the dynamic, passive mechanical properties of the lungs and chest wall, elastance (E) and resistance (R), caused by lung volume reduction surgery (LVRS). DESIGN: Prospective data collection. PATIENTS: Nine anesthetized/paralyzed patients with severe emphysema. INTERVENTIONS: Bilateral LVRS. MEASUREMENTS AND RESULTS: From measurements of airway and esophageal pressures and flow during mechanical ventilation throughout the physiologic range of breathing frequency (f) and tidal volume (VT), E and R of the total respiratory system (Ers and Rrs), lungs (EL and RL), and chest wall (Ecw and Rcw) immediately before and after LVRS were calculated. After surgery, Ers, EL, Rrs, and RL were all greatly increased at each combination off and VT (p<0.05). Ecw and Rcw showed no consistent changes (p>0.05). The increases in EL were greatest in those patients with the lowest residual volumes, highest FEV1 values, and highest maximum voluntary ventilations measured 3 months preoperatively (p<0.05); the increases in RL were greatest in those patients with the lowest preoperative residual volumes (p<0.05). The largest increases in RL were in those patients with the largest decreases in residual volume and total lung capacity, measured 3 months postoperatively, caused by LVRS (p<0.05). CONCLUSION: Acute effects of LVRS are large increases in lung elastic tension and resistance; these increases need to be considered in immediate postoperative care, and can be predicted roughly from results of preoperative pulmonary function tests.

Thermal stress in teeth.

Observations of crack damage in the tooth structure from in vivo studies and in vitro experimental thermal cycling studies were combined with numerical analysis techniques to identify and isolate the influence of thermal stresses on the creation and propagation of cracks in teeth. The factors considered in this study included: (a) variations in tooth type or geometry (molar, bicuspid, etc.), (b) tooth age, (c) material properties of the tooth, (d) the magnitude of the change in the temperature of the environment surrounding the tooth, and (e) the thermal resistance between the tooth and the medium surrounding the tooth.

Studies of porcine reproductive and respiratory syndrome (PRRS) virus infection in avian species.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a recently recognized virus of swine. As a newly emerging virus, much of the basic information regarding PRRSV is in the process of discovery. We report three experiments with PRRSV in birds, and a fourth experiment to evaluate the infectivity and transmissibility of avian-derived PRRSV in swine. Experiment 1 compared the susceptibility of Muscovy ducks, Mallard ducks, guinea fowl, and chickens to PRRSV. Birds were exposed to PRRSV (ATCC VR-2402) in drinking water and virus isolation was attempted from feces collected from cages. Based on the duration of fecal shedding of the virus, this experiment showed that Mallard ducks were particularly susceptible to PRRSV. Experiment 2 was done in mallards to corroborate and augment the observations of experiment 1. Virus was isolated from pooled mallard feces up to 25 days post exposure (PE) and from the intestinal contents of 8 of 20 birds euthanized on day 38 PE. No gross or microscopic lesions were observed in ducks collected between 0 and 15 days PE. Experiment 3 evaluated the infectivity and transmissibility of mallard-derived PRRSV in mallards. A cage of mallards orally exposed to PRRSV shed the virus in feces. Exposure of a second cage of mallards to feces from the first cage resulted in fecal shedding of PRRSV by birds in cage two. In turn, exposure to feces from the second cage led to fecal shedding by mallards in a third cage. Experiment 4 assessed the infectivity and transmissibility of mallard-derived virus in swine. Pigs intranasally exposed to PRRSV isolaed from mallard feces in experiment 2 became viremic, seroconverted by ELISA, and transmitted the virus to sentinel swine. Collectively, these studies show that the possibility exists for avian species to be involved in the epidemiology of PRRSV. This is the first report of PRRSV infection in a species other than swine.

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.

Porcine reproductive and respiratory syndrome virus: a persistent infection.

Persistent infection with porcine reproductive and respiratory syndrome virus (PRRSV) was shown in experimentally infected pigs by isolation of virus from oropharyngeal samples for up to 157 days after challenge. Four 4 week old, conventional, PRRSV antibody-negative pigs were intranasally inoculated with PRRSV (ATCC VR-2402). Serum samples were collected every 2 to 3 days until day 42 post inoculation (PI), then approximately every 14 days until day 213 PI. Fecal samples were collected at the time of serum collection through day 35 PI. Oropharyngeal samples were collected at the time of serum collection from 56 to 213 days PI by scraping the oropharyngeal area with a sterile spoon, especially targeting the palatine tonsil. Turbinate, tonsil, lung, parotid salivary gland, spleen, lymph nodes and serum were collected postmortem on day 220 PI. Virus isolation (VI) on porcine alveolar macrophage cultures was attempted on all serum, fecal and oropharyngeal samples, as well as tissues collected postmortem. Postmortem tonsil tissues and selected fecal samples were also assayed for the presence of PRRSV RNA by the polymerase chain reaction (PCR). Serum antibody titers were determined by IFA, ELISA and SVN. Virus was isolated from all serum samples collected on days 2 to 11 PI and intermittently for up to 23 days in two pigs. No PRRSV was isolated from fecal samples, but 3 of 24 samples were PCR positive, suggesting the presence of inactivated virus. Oropharyngeal samples from each pig were VI positive 1 or more times between 56 and 157 days PI. Oropharyngeal samples from 3 of 4 pigs were VI positive on days 56, 70 and 84 PI. Virus was isolated from one pig on day 157 PI, 134 days after the last isolation of virus from serum from this animal. Virus was isolated from oropharyngeal samples for several weeks after the maximum serum antibody response, as measured by IFA, ELISA and SVN tests. All tissues collected postmortem were VI negative and postmortem tonsil samples were also negative by PCR. An important element in the transmission of PRRSV is the duration of virus shedding. The results of this study provided direct evidence of persistent PRRSV infection and explain field observations of long-term herd infection and transmission via purchase of clinically normal, but PRRSV infected, animals. Effective prevention and control strategies will need to be developed in the context of these results.

Expression of Aleutian mink disease parvovirus capsid proteins in a baculovirus expression system for potential diagnostic use.

A 2.3-kb cDNA clone encoding Aleutian mink disease parvovirus (ADV) structural proteins VP1 and VP2 was inserted into the polyhedron gene of Autographa californica nuclear polyhedrosis virus (AcNPV) and expressed by the recombinant virus, AcADV-1, in Spodoptera frugiperda-9 cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western immunoblot analysis (WIA) indicated that synthesis of both VP1 and VP2 was being directed by AcADV-1. Fluorescence microscopic examination of AcADV-1-infected S. frugiperda-9 cells indicated that the recombinant protein was present within the nucleus of the cells, and electron microscopic examination of these cells revealed the presence of small particles 23-25 nm in diameter. Structures resembling empty ADV capsids could be purified on CsCl density gradients, thus indicating that the ADV proteins were self-assembling. The antigenicity of recombinant VP1 and VP2 was evaluated by WIA. Sera collected from 16 mink prior to infection with ADV did not react with VP1 and VP2. Ten sera collected from mink with counter current immunoelectrophoresis (CIE) titers greater than 4 (log2) reacted with VP1 and VP2 in WIA. Two of 6 sera with CIE titers of 4 and 1 of 14 sera with CIE titers < 4 reacted with the recombinant proteins. These results suggest that baculovirus recombinant ADV capsid proteins may be useful as diagnostic antigens.

Detection of pseudorabies virus infection in subunit-vaccinated and nonvaccinated pigs using a nucleocapsid-based enzyme-linked immunosorbent assay.

The potential of a pseudorabies virus (PRV) nucleocapsid protein (NC)-based enzyme-linked immunosorbent assay (ELISA) as a screening assay for PRV infection in subunit-vaccinated and nonvaccinated pigs was studied. The NC-ELISA compared favorably to a commercial ELISA for detecting PRV infection in nonvaccinated pigs. Virus-specific antibody was first detected by the NC-ELISA between days 14 and 21 in 5 pigs challenged intranasally with 10(4) PFU of virus. Antibody continued to be detected in these pigs through day 42, when the experiment was terminated. The NC-ELISA also detected antibody in 23 of 24 pigs from PRV-infected herds. In contrast, the commercial ELISA detected antibody 1 week earlier than the NC-ELISA in experimentally infected pigs but failed to detect antibody in 3 naturally exposed pigs that were identified by the NC-ELISA. Infection in these animals was confirmed by radioimmunoprecipitation analysis. The potential usefulness of the NC-ELISA for detecting infection in vaccinated pigs was also evaluated. The nucleocapsid-specific antibody responses of 10 PRV envelope glycoprotein subunit-vaccinated pigs were monitored prior to and following nasal exposure to a low dose (10(2.3) PFU) of PRV. Sera were collected periodically for 113 days after infection. Nucleocapsid-specific antibody responses measured by the NC-ELISA remained below the positive threshold before challenge but increased dramatically following virus exposure. Maximum ELISA responses were obtained on day 32 postchallenge (p.c.). Mean ELISA responses decreased thereafter but remained well above the positive threshold on day 113 p.c. PRV nucleocapsid protein can be used effectively as antigen in the ELISA for detecting PRV infection in both nonvaccinated and subunit-vaccinated pigs.

Characterization of the humoral immune response to porcine reproductive and respiratory syndrome (PRRS) virus infection.

The development of the humoral immune response against porcine reproductive and respiratory syndrome (PRRS) virus was monitored by an indirect fluorescent antibody (IFA) test, immunoperoxidase monolayer assay (IPMA), enzyme-linked immunosorbent assay (ELISA), and serum virus neutralization (SVN) test over a 105-day period in 8 pigs experimentally infected with ATCC strain VR-2402. Specific antibodies against PRRS virus were first detected by the IFA test, IPMA, ELISA, and the SVN test 9-11, 5-9, 9-13, and 9-28 days postinoculation (PI), respectively, and reached their maximum values by 4-5, 5-6, 4-6, and 10-11 weeks PI, respectively, thereafter. After reaching maximum value, all assays showed a decline in antibody levels. Assuming a constant rate of antibody decay, it was estimated by regression analysis that the ELISA, IFA, IPMA, and SVN antibody titers would approach the lower limits of detection by approximately days 137, 158, 324, and 356 PI, respectively. In this study, the immunoperoxidase monolayer assay appeared to offer slightly better performance relative to the IFA test, ELISA, and SVN test in terms of earlier detection and slower rate of decline in antibody titers. Western immunoblot analysis revealed that antibody specific for the 15-kD viral protein was present in all pigs by 7 days PI and persisted throughout the 105-day observation period. Initial detection of antibodies to the 19-, 23-, and 26-kD proteins varied among pigs, ranging from 9 to 35 days PI. Thereafter, the antibody responses to these 3 viral proteins of PRRS virus continued to be detected throughout the 105-day study period.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of monetary reinforcement to reduce the cigarette smoking of persons with schizophrenia: a feasibility study.

The feasibility of using monetary reinforcement to promote abstinence from substance use in adult individuals with schizophrenia was addressed. Cigarette smoking was studied as an exemplar of drug use in 11 individuals with schizophrenia by use of a within-subject experimental design. The study duration was 3 weeks, with weeks 1 and 3 serving as baseline conditions and week 2 serving as the intervention condition; in the latter, patients could earn money by abstaining from cigarette smoking. Abstinence was significantly greater during the intervention condition than during the baseline conditions. These results illustrate the potential sensitivity of drug use in this population to reinforcement contingencies, suggesting that contingency-management interventions are a feasible option for treating the substance abuse of individuals with schizophrenia.

Changes in midwives' attitudes to their professional role following the implementation of the midwifery development unit.

OBJECTIVE: to examine changes in midwives' attitudes to their professional role following the implementation of the midwifery development unit (MDU). DESIGN: prospective cohort study. SETTING: the MDU is based at a major teaching hospital in Glasgow, UK. The MDU midwives provide care via a new self-rostering system which is intended to improve continuity of care. Midwives aim to provide total care for each woman from the antenatal period through delivery and the postnatal period. PARTICIPANTS: 21 midwives who joined the MDU were compared with a group of 64 midwives at the hospital who were also eligible and who continued in their usual pattern of work (non-MDU midwives). MEASUREMENTS: an audit questionnaire was distributed to MDU and non-MDU midwives prior to the implementation of the unit and about 15 months afterwards. In addition, the MDU midwives were sent the questionnaire every three months. Extra questions were added at each time period in order to identify specific problems. This information was then fed back to the midwifery management team to aid in the planning and implementation of the care programme. FINDINGS: the MDU midwives experienced a significant positive change in attitudes; no significant change was evident for the non-MDU group. There was no evidence of increased stress in the MDU midwives. In general, both groups of midwives had positive attitudes towards the unit and felt that MDU-style care had a role to play in the future provision of maternity care. A number of areas of concern were also highlighted, such as the system of liaison with colleagues. CONCLUSIONS: innovative models of midwifery care such as an MDU can have a positive impact on midwives' attitudes towards their professional role. IMPLICATIONS FOR PRACTICE: if change is managed in a systematic manner which involves the midwives, it may be possible to increase midwives' professional satisfaction, while at the same time minimising any negative effects such as increased stress.

Satisfaction with midwife-managed care in different time periods: a randomised controlled trial of 1299 women.

OBJECTIVE: To compare women's satisfaction with midwife-managed care with 'shared care' over three different time periods. DESIGN: Randomised controlled trial. SETTING: Glasgow Royal Maternity Hospital, Glasgow, UK. PARTICIPANTS: 1299 women experiencing normal pregnancy (consent rate: 82%). Six hundred and forty-eight women were randomised to midwife-managed care and 651 to 'shared care'. METHODS: Three self-report questionnaires were sent to women's homes. The questionnaires examined: satisfaction with antenatal care at 34-35 weeks' gestation, and satisfaction with intrapartum, hospital- and home-based postnatal care at seven weeks postnatally. The third questionnaire reviewed satisfaction with intrapartum care seven months after delivery. FINDINGS: Women in both groups were satisfied. However, women in the midwife-managed group were more highly satisfied in relation to the dimensions examined: relationships with staff, information transfer, choices and decisions, and social support. The differences between the two groups were evident for all time periods (i.e. antenatal, intrapartum and postnatal periods) and were sustained at seven-month follow-up. This is illustrated in the mean scores for relationships with staff, as measured at 34-35 weeks' gestation (possible range -2; very negative attitudes to 2; very positive attitudes). Women in the midwife-managed group scored a mean of 1.22 compared to 0.74 for the 'shared care' group (mean diff: 0.48; 95% CI: 0.42 to 0.55). While women in both groups were more likely to make positive rather than negative comments in open-ended questions, the midwife-managed group were more likely to make positive comments whereas the 'shared care' group were more likely to make negative comments. CONCLUSION: Midwife-managed care for healthy pregnant women which is integrated into existing services improves satisfaction with antenatal, intrapartum and postnatal care.

Colostral transfer of Clostridium perfringens type C beta antitoxin in swine.

Nine bred gilts were vaccinated with 2 doses of a Clostridium perfringens type C toxoid at a 5-week interval. Time of vaccination during gestation differed among the gilts. Clostridium perfringens beta antitoxin in colostral samples and in serum samples was titrated in mice. Blood was collected from 2 to 5 neonatal pigs from each dam (total = 32 pigs) when the pigs were 36 to 48 hours old. Antitoxin titers in colostrum were 123 to 4.5 IU/ml, indicating considerable variation in individual responses of the gilts to toxoid. Serum titers of neonatal pigs reflected colostrum titers of their dams. This colostrum-to-serum titer correlation was essentially a straight-line fit by least-squares linear regression analysis, establishing a direct proportional relationship between colostrum titers and serum titers of neonatal pigs. In the dams, a correlation was not found between colostral titers and serum titers of blood samples collected 2 weeks after collection of colostrum.

Studies on the ability of a 98-kilodalton pseudorabies virus diagnostic antigen to detect latent infections induced by low-dose exposure to the virus.

The effect of low-dose challenge of immunity with pseudorabies virus (PRV) on subunit-vaccinated pigs was studied in 2 experiments. In the first experiment, we studied the effect of challenge dose on the antibody response to an early excreted 98-kilodalton PRV-glycoprotein that was used as a diagnostic antigen in the ELISA. In the second experiment, we studied the effect of low doses of virus on the establishment of latent infections in subunit-vaccinated pigs. The relationship of virus exposure dose and vaccine dose to the response of pigs to diagnostic antigen was studied in 18 pigs. Two groups of 3 pigs were vaccinated with a total of 200 micrograms of a lectin-derived PRV subunit vaccine over a 5-week period. Two groups of 3 pigs were similarly vaccinated with a total of 100 micrograms. Two groups of 3 pigs served as nonvaccinated controls. One group of pigs from each of the preceding categories was intranasally exposed to 10(6.0) and 10(2.7) plaque-forming units (PFU) of virus. Antibody to diagnostic antigen was detected by the ELISA and radioimmunoprecipitation 3 to 7 days earlier in pigs exposed to 10(6.0) PFU, demonstrating that the size of the virus challenge dose affects the antibody response to diagnostic antigen. The establishment of latent infections by low PRV doses and the ability to detect these infections was studied in 10 subunit-vaccinated pigs. Each pig was intranasally exposed to 10(2.3) PFU of virus (day 0).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody response of pseudorabies virus subunit-vaccinated pigs to viral nucleocapsid proteins following low-dose virus challenge of immunity.

The antibody response to pseudorabies virus nucleocapsid proteins (NCP) was evaluated by the western immunoblot analysis before and after challenge of immunity by nasal inoculation of 10(2.3) plaque-forming units of virus in 10 pigs that had been vaccinated with pseudorabies virus envelope glycoproteins. Antibody to 5 NCP with molecular mass of 140, 63, 41, 34, and 23 kD was first detected in vaccinated and nonvaccinated pigs on day 14 after challenge of immunity. Antibody to 2 of the 5 NCP continued to be detected through day 113 in 9 of 10 vaccinated pigs. Beyond day 32, antibody to NCP was not detected in 1 vaccinated pig. The 23-, 34-, and 41-kD proteins were the most immunogenic. Antibody to each of these proteins was first detected on day 14 in 10, 10, and 8 pigs, respectively. Seven, 6, and 8 pigs, respectively, were antibody-positive for these proteins on day 113. The 140- and 63-kD proteins were the least immunogenic. Antibody to these proteins was detected in 8 and 9 pigs, respectively, on day 14, and in 4 and 5 pigs, respectively, on day 113. Chi-square analysis for dependency indicated that the antibody response to the 140- and 63-kD proteins was interdependent. These results suggested that combinations of NCP may be useful as nonvaccine diagnostic antigens.

Excretion of porcine reproductive and respiratory syndrome virus in semen after experimentally induced infection in boars.

Four boars intranasally inoculated with porcine reproductive and respiratory syndrome (PRRS) virus were monitored for 56 days after exposure for changes in semen characteristics and for the presence of virus in the semen. Clinically, 2 of 4 boars had mild respiratory signs of 1 day's duration after infection. Changes in appetite, behavior, or libido were not detected. All boars seroconverted on the indirect fluorescent antibody and serum virus neutralization tests by day 14 after inoculation. Virus was isolated from serum between days 7 and 14 after inoculation. During the monitoring period, semen volume decreased and pH correspondingly increased; however, this change began 7 to 10 days prior to infection. Differences in sperm morphologic features, concentration, or motility between the preinfection and postinfection samples were not observed. The PRRS virus was detected in semen at the first collection in each of the 4 boars (ie, 3 or 5 days after challenge exposure). Virus was detected in nearly all semen samples collected from the 4 infected boars through days 13, 25, 27, and 43, respectively. Neither gross nor microscopic lesions attributable to PRRS virus were observed in tissues collected at the termination of the experiment (day 56), and virus isolation results from reproductive tissues were negative.

Comparison of field olfactometers in a controlled chamber using hydrogen sulfide as the test odorant.

A standard method for measuring and quantifying odour in the ambient air utilizes a portable odour detecting and measuring device known as a field olfactometer (US Public Health Service Project Grant A-58-541). The field olfactometer dynamically dilutes the ambient air with carbon-filtered air in distinct ratios known as "Dilutions-to-Threshold" dilution factors (D/Ts), i.e. 2, 4, 7, 15, etc. Thirteen US states and several cities in North America currently utilize field olfactometry as a key component of determining compliance to odour regulations and ordinances. A controlled environmental chamber was utilized, with hydrogen sulfide as the known test odorant. A hydrogen sulfide environment was created in this controlled chamber using an Advanced Calibration Designs, Inc. Cal2000 Hydrogen Sulfide Generator. The hydrogen sulfide concentration inside the chamber was monitored using an Arizona Instruments, Inc. Jerome Model 631 H2S Analyzer. When the environmental chamber reached a desired test concentration, test operators entered the chamber. The dilution-to-threshold odour concentration was measured using a Nasal Ranger Field Olfactometer (St Croix Sensory, Inc.) and a Barnebey Sutcliffe Corp. Scentometer. The actual hydrogen sulfide concentration was also measured at the location in the room where the operators were standing while using the two types of field olfactometers. This paper presents a correlation between dilution-to-threshold values (D/T) and hydrogen sulfide ambient concentration. For example, a D/T of 7 corresponds to ambient H2S concentrations of 5.7-15.6 microg/m3 (4-11 ppbv). During this study, no significant difference was found between results obtained using the Scentometer or the Nasal Ranger (r = 0.82). Also, no significant difference was found between results of multiple Nasal Ranger users (p = 0.309). The field olfactometers yielded hydrogen sulfide thresholds of 0.7-3.0 microg/m3 (0.5-2.0 ppbv). Laboratory olfactometry yielded comparable thresholds of 0.64-1.3 microg/m3 (0.45-0.9 ppbv). These thresholds are consistent with published values.