Which cytological criteria are the most discriminative to distinguish carcinoma, lymphoma, and soft-tissue sarcoma? A probabilistic approach.

The reliability of fine-needle aspiration cytology (FNA) for distinguishing between carcinoma, lymphoma, and sarcoma was established in a previous study (Thunnissen et al., Cytopathology 1993; 4:107-114). The purpose of this study was to investigate which criteria were useful for a probabilistic diagnosis. A total of 78 randomly chosen FNA smears (31 carcinomas, 24 lymphomas, and 23 sarcomas) was sent around and read "blindly" by six cytopathologists. Each pathologist completed a list of 16 criteria for every case. Histology was used as a reference standard. A statistical analysis led to the selection of three criteria: "lymphoglandular bodies," "well-defined clusters," and "spindle-cell nuclei," associated with lymphoma, carcinoma, and soft-tissue sarcoma, respectively. Given the scores on these criteria, the probabilities to be assigned to the three diagnostic categories can be read from a table. It turns out, as one might expect, that the classification of the most probable disease is pretty reliable if one cytologic criterion scores much higher than the other two criteria. On other cases, fuzziness appears and misclassifications are far from improbable. This study offers a general cytologic approach. The cytologic criteria "lymphoglandular bodies," "well-defined clusters," and "spindle-cell nuclei" can be used both in daily practice and in education to assign posterior probabilities to carcinoma, lymphoma, and soft-tissue sarcoma.

Seroprevalence of porcine reproductive and respiratory syndrome virus in Dutch weaning pigs.

To determine whether under Dutch field conditions PRRSV infection occurs in weaning pigs before the finishing period, a cross-sectional study was performed on 32 breeding farms to estimate the seroprevalence of antibodies directed against PRRSV in 4- to 5-week-old and 8- to 9-week-old pigs. Farms were visited twice within 5 months, and during each sampling an average of 20 sera were randomly collected from a unit of 4- to 5-week-old and a unit of 8- to 9-week-old pigs. The sera (n = 2568) were tested in the IDEXX-ELISA for the presence of antibodies directed against PRRSV. The seroprevalence of PRRSV in 4- to 5-week-old pigs and 8- to 9-week-old pigs varied between both samplings for each farm. The seroprevalence in the younger pigs was significantly higher than in the older pigs for both samplings (p < 0.05), suggesting the presence of maternal antibodies. In addition, a longitudinal study was performed to evaluate the IDEXX-ELISA in detecting maternal antibodies directed against PRRSV and to determine the rate of decline of these antibodies in field sera. From serological results of eight litters, an average decay function was computed to quantify the maternal immunity to PRRSV. A seroprevalence in 8- to 9-weeks-old pigs of > or = 0.20 was calculated to indicate an active immune response to PRRSV. In the cross-sectional study in the pigs twenty-three percent of the units with 8- to 9-week-old pigs were considered to have an active serological response against PRRSV. We conclude that most Dutch pigs are seronegative for PRRSV at the start of the finishing period, since the results of this study showed that 77% of the units with 8- to 9-week-old pigs had a seroprevalence < 0.20.

An attenuated bovine herpesvirus 1 marker vaccine induces a better protection than two inactivated marker vaccines.

A comparative study on the efficacy of 3 bovine herpesvirus 1 (BHV1) marker vaccines was carried out. An attenuated gE-negative vaccine, an inactivated gE-negative vaccine and an experimental gD-subunit vaccine were tested twice in a vaccination-challenge experiment in cattle. The attenuated vaccine induced the best clinical protection as evidenced by the total absence of clinical signs and fever in cattle. In addition, the attenuated vaccine reduced the shedding of challenge virus significantly more than the inactivated vaccines. Of the inactivated vaccines, the gE-negative vaccine induced a better clinical protection than the gD-subunit vaccine.

Prediction of the left ventricular mass from the electrocardiogram in systemic hypertension.

Although echocardiography provides a reliable method to determine left ventricular (LV) mass, it may not be available in all settings. Numerous electrocardiographic (ECG) criteria for the detection of LV hypertrophy have been developed, but few attempts have been made to predict the LV mass itself from the ECG. In a community-based survey program in the general population, 277 subjects were identified with untreated diastolic hypertension (diastolic blood pressure 95 to 115 mm Hg, 3 occasions) or isolated systolic hypertension (diastolic blood pressure <95 mm Hg and systolic blood pressure 160 to 220 mm Hg, 3 occasions). All subjects underwent ECG and echocardiography on the same day. A multiple linear regression analysis was performed using a random training sample of the data set (n = 185). The independent variables included both ECG and non-ECG variables. The resulting model was used to predict the LV mass in the remainder of the data set, the validation sample (n = 92). Using sex, age, body surface area, the S-voltage in V1 and V4, and the duration of the terminal P in V1 as independent variables, the model explained 45% of the variance (r = 0.67) in the training sample and 42% (r = 0.65) in the validation sample. This result exceeded that of 2 existing ECG models for LV mass (r = 0.40 and 0.41). The correlations between LV mass and combinations of ECG variables used for the detection of LV hypertrophy, such as the Sokolow-Lyon Voltage (r = 0.03) and the Cornell Voltage (r = 0.31), were comparatively low. In settings where echocardiography is not available or is too expensive and time-consuming, prediction of the LV mass from the ECG may offer a valuable alternative.

Potency control of modified live viral vaccines for veterinary use.

This paper reviews various aspects of efficacy, and methods for assaying the potency of modified live viral vaccines. The pros and cons of parametric versus non-parametric methods for analysis of potency assays are discussed and critical levels of protection, as determined by the target(s) of vaccination, are exemplified. Recommendations are presented for designing potency assays on master virus seeds and vaccine batches.

Potency control of modified live viral vaccines for veterinary use.

This paper reviews various aspects of efficacy, and methods for assaying the potency of modified live viral vaccines. The pros and cons of parametric versus non-parametric methods for analysis of potency assays are discussed and critical levels of protection, as determined by the target(s) of vaccination, are exemplified. Recommendations are presented for designing potency assays on master virus seeds and vaccine batches.