Scintigraphic evaluation of the thoracic spine in the asymptomatic riding horse.

Scintigraphic evaluation of the spinous processes of the equine spine has been done by subjective evaluation of radiotracer uptake in clinically abnormal horses. To determine the range of variation in asymptomatic riding horses, 33 normal horses were examined. Two 60 degrees oblique views of the thoracic and lumbar spine were evaluated subjectively, and a semi quantitative method based on standardized regions of interest in each spinous process in T10-L3 was also applied. A ratio between each spinous process and a reference area (Rib 15 or 16) was calculated. The effects of two different color displays and a smoothing filter were assessed. The results of the subjective evaluation was compared to the calculated ratios, and the associations between age, gender, weight, height, use and increased radiotracer uptake, and ratios were analyzed. No significant association was found between age, gender, weight, height, use and increased radiotracer uptake, or ratio. One or more areas of increased radiotracer uptake between T13 and T18 were common in the asymptomatic riding horse, which may have implications for the interpretation of clinical patients. The blue, green and red color display had a higher sensitivity for detecting increased radiotracer uptake compared to the continuous grayscale. The smoothing filter used in this study had no effect on the detection of areas with increased radiotracer uptake. The association between the results of the subjective evaluation and the semi quantitative method was apparent when analyzed in T13-17. To evaluate if the semi quantitative method can replace the subjective evaluation, studies on clinically affected horses are necessary.

Scintigraphy of the sacroiliac joint region in asymptomatic riding horses: scintigraphic appearance and evaluation of method.

The sacroiliac region in 33 clinically normal riding horses was examined with scintigraphy to determine the normal scintigraphic appearance, to evaluate a semiquantitative method used to calculate a sacroiliac joint (SI joint) ratio, and to identify factors that affect the scintigraphic appearance of the pelvis. The scintigraphic examination included dorsal views of each SI joint region and one lateral view of the urinary bladder. Two predefined areas (the SI joint and the area between the tuber sacrale and the SI joint) were evaluated subjectively by comparing the intensity in each area to the intensity in the tuber sacrale, and a semiquantitative method was applied on the images to calculate an SI joint ratio. The thickness of the muscle mass overlying each SI joint was measured by using ultrasound. A corrected ratio was calculated based on a corrected pixel count for each SI joint. Of 29 evaluated horses, 28 had normal radiotracer uptake in the SI joints and 10 horses had symmetric normal radiotracer uptake in the area between the tuber sacrale and the SI joint. The mean SI joint ratio was 0.53 on both the left and right sides, and the mean corrected SI joint ratio was 2.15 on the left side and 2.13 on the right side. Factors that affect the scintigraphic appearance of the pelvis were identified and included attenuation, radioactive urine, and muscle symmetry. The muscle thickness ranged from 8-11 cm, causing 71-82% attenuation. Radioactive urine in the urinary bladder was located ventral to the SI joint region in 16 horses, and four of these were excluded from further evaluation because of risk of misinterpretation. A visual assessment of symmetry of the horses' gluteal muscle mass was compared with the ultrasound measurements. Fourteen horses (14/33) were regarded symmetric by both techniques. Soft tissue attenuation was found to severely compromise the result and indicated that only lesions in the SI joint with severely increased radiotracer uptake can be detected with scintigraphy. Knowledge about presence of radioactive urine ventral to the SI joint region and assessment of muscle symmetry is essential for a correct subjective evaluation. Any situation with difference in muscle mass between the left and right side of the pelvis will give a false impression of increased radiotracer uptake on the side with lesser muscle mass.

Irradiation-induced expression of hyaluronan (HA) synthase 2 and hyaluronidase 2 genes in rat lung tissue accompanies active turnover of HA and induction of types I and III collagen gene expression.

Hyaluronan (HA) is a linear glycosaminoglycan that accumulates in the interstitium of injured lung and inhibits gas exchange between air and blood. In the present study we investigated the molecular mechanisms behind the local turnover of HA during the early phase of irradiation-evoked lung fibrosis in rats. Irradiation with a single dose of 30 Gy to the lower part of the right lung of rats induced an accumulation of HA in bronchoalveolar lavage fluid 6 wk after irradiation, followed by return to almost normal levels at 10 wk after irradiation. This was parallelled with a transient downregulation of HA receptors on alveolar macrophages (AMs); 4 and 6 wk after irradiation the binding of [(3)H]HA to AMs was decreased to about 50% of that of AMs from nonirradiated control rats, returning to almost normal level at 10 wk after irradiation. Analysis of the expression of rat HA synthase (HAS) isoforms (rHAS1, rHAS2, and rHAS3) and rat hyaluronidases (rHYAL1 and rHYAL2) by Northern blotting revealed an upregulation of rHAS2 messenger RNA at 4, 6, and 10 wk after irradiation, but a progressive decrease in the constitutive expression of rHYAL2 at 6 and 10 wk after irradiation; rHAS1 was undetectable, whereas rHAS3 and rHYAL1 were faintly detectable. Although transforming growth factor-beta1 stimulated HA production by normal lung fibroblasts, it inhibited HYAL activity in lysosomes and HYAL activity released into the culture media. Another interesting observation was that HA fragments, which likely result from the action of HYAL, induced expression of types I and III collagen genes. Our results indicate that rHAS2 and rHYAL2 are involved in the turnover of HA during the early phase of lung injury and that rHAS2 and rHYAL2 as well as HA fragments may play important roles in the pathogenesis of lung fibrosis.

A mechanical study of six digital pulley reconstruction techniques: Part I. Mechanical effectiveness.

A laboratory study on fresh-frozen human cadaver limbs compared six types of flexor tendon pulley reconstruction in the fingers. The reconstructions used were those described by (1) Bunnell, (2) Karev, (3) Weilby, and (4) Lister, and two types developed by us that have not been previously described. The pulleys were studied in specific configurations to determine their effectiveness in transforming tendon excursion into finger flexion. In each finger, comparison was made between the amount of tendon excursion required for full flexion with an intact pulley system versus the various types of reconstructed pulleys. The ratio of these two values was defined as the mechanical effectiveness of the pulley reconstruction. The Karve reconstruction was most effective at 108.2%, which was significantly different from the other five reconstructions (p less than 0.01). The remaining reconstructions ranged in effectiveness from 80.0% to 88.5%.

A mechanical study of six digital pulley reconstruction techniques: Part II. Strength of individual reconstructions.

A laboratory study was done on fresh-frozen human cadaver limbs, using six types of pulley reconstructions about the flexor tendons of the fingers. The reconstructions used were those described by (1) Bunnell, (2) Karev, (3) Weilby, and (4) Lister, and two types developed by us that have not been previously described. The pulleys were tested at constant strain rate to failure with the peak force recorded as the breaking strength. A total of 385 reconstructed pulleys were tested and the results were analyzed statistically. A new "loop and one half" pulley reconstruction was significantly stronger than the other five reconstructions (p less than 0.01) with an average load to failure of 22.5 kilograms-force. The other pulley reconstructions varied in average breaking strength from 2.8 kilograms-force to 18.4 kilograms-force.