[Is ultrasound equal to X-ray in pediatric fracture diagnosis?]

PURPOSE

Ultrasound is currently not established for the diagnosis of fractures. The aim of this study was to compare ultrasound and X-ray beyond their use solely for the identification of fractures, i. e., for the detection of fracture type and dislocation for pediatric fracture diagnosis.

MATERIALS AND METHODS

Limb bones of dead young pigs served as a model for pediatric bones. The fractured bones were examined with ultrasound, X-ray, and CT, which served as the gold standard.

RESULTS

162 of 248 bones were fractured. 130 fractures were identified using ultrasound, and 148 using X-ray. There were some advantages of X-ray over ultrasound in the detection of fracture type (80 correct results using X-ray, 66 correct results using ultrasound). Ultrasound, however, was superior to X-ray for dislocation identification (41 correct results using X-ray, 51 correct results using ultrasound). Both findings were not statistically significant after adjustment for multiple testing.

CONCLUSION

Ultrasound not only has comparable sensitivity to that of X-ray for the identification of limb fractures but is also equally effective for the diagnosis of fracture type and dislocation. Thus, ultrasound can be used as an adequate alternative method to X-ray for pediatric fracture diagnosis.

Recrudescence of spermatogenesis in the dog following downregulation using a slow release GnRH agonist implant

The present study examined the degree to which downregulation with a GnRH agonist impaired spermatogenesis and the time course of morphological and hormonal changes that occurred during recrudescence of spermatogenesis. Using a control group (group 1, n = 5) of dogs, the effect of a removable slow release GnRH-agonist implant was investigated in beagle dogs (group 2, n = 30). The implant was removed after 5 months (week 0) and three to four dogs were castrated at weeks 0, 3, 6, 9, 12, 15, 18, 21 and 24. The degree of downregulation and recrudescence of spermatogenesis was assessed by evaluation of 200 tubular cross-sections, resulting in an assigning of dogs of group 2 to testis developmental groups (DG) according to the most developed germ cell observed: DG A, spermatocytes; DG B, round spermatids; DG C, elongating spermatids and DG D, elongated spermatids. Downregulation led to an arrest of spermatogenesis at the level of spermatogonia/primary spermatocytes. The time course of recrudescence showed high individual variations and the number of dogs falling into DG A, B, C and D was 4, 3, 6 and 17 respectively. Spermatogenesis in group 2, DG D was not different from group 1 (control). In DG A, mean area of Leydig-cell nuclei was lower (p < 0.001) than in the other DG and group 1 and resembled that of juvenile dogs (group 3, n = 3); nuclei of Sertoli cells had changed from more flat/polygonal (group 1, group 2, DG C and D) to round/ovoid and had moved to a more luminal position. As indicated by basal testosterone (T), luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations at implant removal, full downregulation had been obtained. Testosterone, LH and FSH concentrations [X(g) (DF), ng/ml] increased (p < 0.05) from implant removal to DG B [T: 0.1 (1.24) vs 2.12 (2.31); LH: 0.2 (2.15) vs 1.11 (1.7); FSH: 0.37 (3.50) vs 6.37 (1.68)] and were more or less constant thereafter indicating that onset of spermatogenesis was related to an increase of plasma T occurring in a very narrow time window. Following GnRH implantation, the size of the testes and the prostate decreased by approximately 55% (p < 0.001), they increased to sizes similar to pre-treatment values following implant removal.

[Analysis of the statistical value of various commercially available stool tests - a comparison of one stool sample in correlation to colonoscopy]

INTRODUCTION

Guajac based fecal occult blood tests have proven to reduce mortality of colorectal cancer - despite their unsatisfactory statistical values. The potential of newer tests is yet inconclusive. We compared two guajac based, four immunochemical and the M2-PK test with colonoscopic and histological results as a reference.

METHODS

In 1128 stool samples of patients undergoing (screening) colonoscopy the mentioned tests were performed.

RESULTS

Positivity rate was 1.9 to 4.1 % for guajac based and immunochemical tests, M2-PK reached 11.6 %. In case of advanced neoplasias, no significant differences in sensitivity (7.3 - 20 %), specifity (96.6 - 98.4 %), positive predictive value (16.7 - 30.6 %) or accuracy (92.9 - 94.0 %) between guajac based and immunochemical tests were encountered. The slightly higher sensitivity of M2-PK (27.3 %) did not reach statistical significance - however the comparatively low specifity (89.2 %) and accuracy (86.2 %) were clearly lower compared to all other tests. Regarding all neoplasia, immunochemical tests performed better than conventional hemoccult, but the difference did not reach statistical significance. In this group, the sensitivity of M2-PK is clearly better, but specifity is clearly inferior to all other tests.

DISCUSSION

Low sensitivity and low predictive values are explained by the study design with single test and low prevalence of neoplasia. Due to small numbers, there is only a trend, but no significant difference between the performance of conventional hemoccult compared with immunochemical and high senstitive guajac tests. Because of its low specificity, M2-PK is not an appropriate screening test for colorectal neoplasia.

Detection of artificial air space opacities with digital radiography: ex vivo study on enhanced latitude post-processing

PURPOSE

To evaluate in a.-p. digital chest radiograms of an ex vivo system if increased latitude and enhanced image detail contrast (EVP) improve the accuracy of detecting artificial air space opacities in parts of the lung that are superimposed by the diaphragm.

MATERIALS AND METHODS

19 porcine lungs were inflated inside a chest phantom, prepared with 20-50 ml gelatin-stabilized liquid to generate alveolar air space opacities, and examined with direct radiography (3.0 × 2.5 k detector/ 125 kVp/ 4 mAs). 276 a.-p. images with and without EVP of 1.0-3.0 were presented to 6 observers. 8 regions were read for opacities, the reference was defined by CT. Statistics included sensitivity/specificity, interobserver variability, and calculation of Az (area under ROC curve).

RESULTS

Behind the diaphragm (opacities in 32/92 regions), the median sensitivity increased from 0.35 without EVP to 0.53-0.56 at EVP 1.5-3.0 (significant in 5/6 observers). The specificity decreased from 0.96 to 0.90 (significant in 6/6), and the Az value and interobserver correlation increased from 0.66 to 0.74 and 0.39 to 0.48, respectively. Above the diaphragm, the median sensitivity for artificial opacities (136/276 regions) increased from 0.71 to 0.77-0.82 with EVP (significant in 4/6 observers). The specificity and Az value decreased from 0.76 to 0.62 and 0.74 to 0.70, respectively, (significant in 3/6).

CONCLUSION

In this ex vivo experiment, EVP improved the diagnostic accuracy for artificial air space opacities in the superimposed parts of the lung (area under the ROC curve). Above the diaphragm, the accuracy was not affected due to a tradeoff in sensitivity/specificity.

[Rational management of atrial fibrillation in intensive care]

Atrial fibrillation (AF) occurs frequently in intensive care unit (ICU) patients and after coronary bypass graft (CABG) and valve surgery, with the peak incidence on postoperative days 2 and 3. Moreover, AF is one of the most common complications after thoracic surgery, e.g. video-assisted thoracic surgery (VATS), lobectomy or extrapleural pneumonectomy. Prophylaxis with beta-blockers can reduce postoperative incidence of AF. The acute treatment of new-onset AF involves rhythm and frequency control and depends on whether the patient is hemodynamically stable or not. Rate control can be performed with beta-blockers or calcium-channel-blockers. Amiodarone is an effective and safe drug for converting AF to sinus rhythm. Conversion of AF should not be attempted 48 h after onset without anticoagulation or transesophageal echocardiography to rule out intracardiac thrombus formation. In order to avoid thromboembolism after cardioversion, an effective anticoagulation is mandatory.

Lung nodule assessment in computed tomography: precision of attenuation measurement based on computer-aided volumetry

PURPOSE

To compare the reproducibility (r) of CT value measurement of pulmonary nodules using volumetry software (LungCare, LC) and manual ROIs (mROI).

MATERIALS AND METHODS

54 artificial nodules in a chest phantom were scanned three times with CT. CT values were measured with LC and mROI. The intrascan-r was assessed with three measurements in the first scan, and the interscan-r with measurements in three consecutive scans (one observer). Intrascan-r und interobserver-r (two obs.) were assessed in the first scan and in contrast-enhanced CT of 51 nodules from 15 patients (kernels b50f and b80f). Intrascan-r and interscan-r were described as the mean range and interobserver-r as the mean difference of CT values. The significance of differences was tested using t-test and sign test.

RESULTS

Reproducibility was significantly higher for volumetry-based measurements in both artificial and patient nodules (range 0.11 vs. 6.16 HU for intrascan-r, 2.22 vs. 7.03 HU for interscan-r, difference 0.11 vs. 18.42 HU for interobserver-r; patients: 1.78 vs. 13.19 HU (b50f-Kernel) and 1.88 vs. 27.4 HU (b80f-Kernel) for intrascan-r, 3.71 vs. 22.43 HU for interobserver-r). Absolute CT values differed significantly between convolution kernels (pat./mROI: 29.3 [b50f] and 151.9 HU [b80f] pat./LC: 5 [b50f] and 147 HU [b80f]).

CONCLUSION

The reproducibility of volumetry-based measurements of CT values in pulmonary nodules is significantly higher and should therefore be recommended, e. g. in dynamic chest CT protocols. Reproducibility does not depend on absolute CT values.

Investigations on the use of C-21-steroids as precursors for placental oestrogen synthesis in the cow

Cotyledonary homogenates from 220 and 270 day pregnant and term cows were incubated (NADPH- and NAD(+)-regenerating system) with 3H-pregnenolone and 3H-progesterone, respectively. Identification of metabolites was based on separation on HPLC and the respective retention times. On days 220/270 the major metabolite formed after incubation with 3H-pregnenolone was progesterone, followed by 17 alpha-hydroxyprogesterone and dehydroepiandrosterone/17 alpha-hydroxypregnenolone; the formation of estrone was low (up to 6%), while it was the major metabolite after incubation of pregnenolone with term placenta. At all stages of pregnancy investigated, the only metabolite found after incubation with 3H-progesterone was 17 alpha-hydroxyprogesterone. These data provide evidence that 17 alpha-hydroxyprogesterone is the endpoint of steroid biosynthesis in the bovine placenta along the delta 4-route and that oestrogen synthesis follows the delta 5-pathway. Based on the high activity of 3 beta-hydroxysteroiddehydrogenase/delta 5/4-isomerase also found on days 220/270, the key enzyme allowing for placental oestrogen synthesis in the cow seems to be cytochrome P450c17 alpha. Thus the situation in the cow is similar to that in the sheep and the increased turnover of pregnenolone into estrone may explain the decrease of placental progesterone production in the cow towards the end of gestation.

Investigations on hormonal changes around parturition in the dog and the occurrence of pregnancy-specific non conjugated oestrogens

Concentrations of progesterone and estradiol-17 beta were determined throughout pregnancy in 6 to 10 bitches (exp. 1); in experiment 2 peripartal changes of estradiol-17 beta, estrone, progesterone, cortisol, prolactin and growth hormone were determined in 5 bitches; in experiment 3 total unconjugated oestrogens were determined by radioimmunoassay and radioreceptorassay in placental tissue from 25, 53, 60 and 64 days pregnant bitches. No pregnancy specific increase of estradiol-17 beta could be observed; estradiol-17 beta levels decreased prior to parturition concomitant with the decrease of progesterone, suggesting a likewise luteal origin of estradiol-17 beta in the pregnant and non pregnant dog. Cortisol and growth hormone concentrations were elevated at the time of parturition, prolactin concentrations remained unchanged but were higher in pregnant than in non pregnant dogs. No hints in respect to a specific placental oestrogen production were obtained when examining placental tissue. The hypothesis is put forward that the high sensitivity of the haematopoietic system of the dog to oestrogen was an important factor in respect to evolution of endocrine control of pregnancy and parturition in this species which-in respect to placental oestrogen production-seems to be different from most other domestic animal species.

Glutaraldehyde and oxidised dextran as crosslinker reagents for chitosan-based scaffolds for cartilage tissue engineering

Chitosan crosslinked with glutaraldehyde or oxidised dextran was studied as a potential scaffold material in tissue engineering for cartilage regeneration. By mixing two solutions of both components it became a gel, which was frozen. After lyophilization a scaffold was generated with interconnected pores with diameters ranging between 120-350 microm. The mechanical properties (yielding point, elastic and viscous moduli), absolute porosity, pore morphology were determined depending on the ratio of chitosan to crosslinker. ATDC5 (murine cell line) and bovine articular chondrocytes (primary cells) were cultured for 14 days on the scaffolds. Cultivation with ATDC5 cells and bovine chondrocytes showed no negative influence of glutaraldehyde on cell vitality and growth.