Borrelia burgdorferi Infection and Lyme Disease in North American Horses: A Consensus Statement.

Borrelia burgdorferi infection is common in horses living in Lyme endemic areas and the geographic range for exposure is increasing. Morbidity after B. burgdorferi infection in horses is unknown. Documented, naturally occurring syndromes attributed to B. burgdorferi infection in horses include neuroborreliosis, uveitis, and cutaneous pseudolymphoma. Although other clinical signs such as lameness and stiffness are reported in horses, these are often not well documented. Diagnosis of Lyme disease is based on exposure to B. burgdorferi, cytology or histopathology of infected fluid or tissue and antigen detection. Treatment of Lyme disease in horses is similar to treatment of humans or small animals but treatment success might not be the same because of species differences in antimicrobial bioavailability and duration of infection before initiation of treatment. There are no approved equine label Lyme vaccines but there is strong evidence that proper vaccination could prevent infection in horses.

Udder development, lactation and ascites in a ewe with an ovarian granulosa cell tumour.

A 20-month-old sexually intact female mixed breed sheep was examined for lameness, unexpected udder development, lactation and anorexia. Tachycardia, tachypnoea, severe abdominal distension and vaginal prolapse were evident upon physical examination. A right hindlimb lameness was present at the walk. The udder was well-developed and milk, normal in appearance, was easily expressed from each teat. Ultrasonographic evaluation revealed a non-pregnant uterus, severe ascites and a large (12 cm diameter) abdominal mass. Although surgical treatment was discussed, the owners elected to euthanase the ewe. Necropsy examination confirmed the presence of severe ascites due to a ruptured ovarian tumour. The tumour was characterised as a granulosa cell tumour histologically. Unexpected udder development and lactation presumably occurred secondary to oestrogen and progesterone production by the tumour. To the authors' knowledge, this is the first report of udder development, lactation and ascites in a ewe secondary to an ovarian granulosa cell tumour.

Vowel quality changes produced by surrounding tone sequences.

In three experiments, we examined whether energy at the same frequency as one of a vowel's harmonics in the F1 region can be captured by a preceding or following sequence of tones. The position of the /I/-/E/ phoneme boundary along an F1 continuum was used to assess the extent of capture. The first two experiments showed that a sequence of tones at 500 Hz (56-msec duration at 10/sec) can perceptually remove added energy at 500 Hz from a steady vowel (F0 = 125 Hz) that forms part of the sequence. The effect is detectable with one preceding tone, asymptotes with four, and is greater when two tones follow the vowel than when none do. Rising and falling sequences of tones (at 62.5-Hz intervals or at whole-tone intervals) differ in their effect. Falling sequences behave much like constant tones at 500 Hz but with less effect, whereas rising sequences show no evidence of removing the added tone. The second experiment replicated the first and also showed that when the vowel is embedded in a rising or a falling sequence of tones that continue after it, the following tones have no effect. The third experiment suggested that the different effects found with rising versus falling sequences are qualitatively predictable on the basis of the additive effects of their constituent tones rather than by virtue of their contour. The experiments indicated that sequences of repeating tones are much more effective at capturing a harmonic from a vowel than are sequences that follow a simple pattern. This result may reflect the operation of a principle of least commitment in auditory grouping.

Mistuning a harmonic of a vowel: grouping and phase effects on vowel quality.

The harmonic sieve has been proposed as a mechanism for excluding extraneous frequency components from the estimate of the pitch of a complex sound. The experiments reported here examine whether a harmonic sieve could also determine whether a particular harmonic contributes to the phonetic quality of a vowel. Mistuning a harmonic in the first formant region of vowels from an /I/-/e/ continuum gave shifts in the phoneme boundary that could be explained by (i) phase effects for small amounts of mistuning and (ii) a harmonic sievelike grouping mechanism for larger amounts of mistuning. Similar grouping criteria to those suggested for pitch may operate for the determination of first formant frequency in voiced speech.

Evidence for direction-specific channels in the processing of frequency modulation.

Evidence is provided for the existence of at least three feature-specific channels in the auditory system. Thresholds for the detection of small repetitive or nonrepetitive frequency changes were measured following various adapting stimuli using a 2IFC procedure in two subjects at 1 kHz. Thresholds for single linear upward frequency sweeps (up sweeps) were increased by a factor of 2 to 3 following exposure to repetitive (8 Hz) up sweeps but not following exposure to down sweeps or tone bursts; correspondingly, thresholds for down-sweep stimuli were increased only by down sweeps. Sinusoidal FM test stimulus thresholds were elevated by both up-sweeps and down-sweeps and to a lesser extent by tone bursts. These results suggest the existence in the auditory system of channels specific to upward FM, downward FM, and probably repetition rate.

A comparison of four methods of predicting arch length.

1. Four arch length prediction equations (Nance, Johnston-Tanaka, Moyers, and Hixon-Oldfather) were compared by examining pretreatment casts, pretreatment intraoral radiographs, and posttreatment casts of forty-one patients of mixed-dentition age. 2. A comparison of correlation coefficients and slopes of the predicted arch length versus the actual arch lengths revealed that the Hixon-Oldfather method conformed closest to the ideal. 3. No combination of the four methods produced a more accurate equation than the single most accurate method. 4. Neither the sex of the patient nor the type of occlusion affected the prediction accuracy of any of the four equations. 5. All methods tend to overpredict the arch length size by 1 to 3 mm., with the exception of the Hixon-Oldfather equation, which underpredicted by approximately 0.5 mm. 6. An analysis of the intrainvestigator error showed a very low standard error of estimate for individual tooth measurements and for the prediction values. 7. A variance analysis showed that most of the variation was due to arch length (85%), a slight amount was due to the prediction method (8%), and 6% of the variation was due to the rater. 8. A low correlation was found between space available versus actual discrepancy and space available versus actual arch length. 9. High correlation coefficients were found for the predicted arch lengths when compared with the actual arch lengths. As expected, the correlation coefficients for the predicted widths of only the canines and premolars compared with the actual widths were not quite as high.