Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions

Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established.     

Impact of automatic orders to discontinue vancomycin therapy on vancomycin use in an antimicrobial stewardship program.

We examined the possible unintended consequences of a 72-hour automatic order to discontinue vancomycin therapy in an antimicrobial stewardship program (ASP). Of 120 patients, 11 had vancomycin therapy discontinued at 72 hours without a call to the ASP, and 7 experienced a treatment interruption of 6-36 hours. All discontinuation of therapy was considered appropriate, and the 7 treatment interruptions did not have clear clinical consequences. Only one-third of patients had ASP stickers that warned of impending discontinuation of vancomycin therapy placed appropriately in the medical record.     

Plasma endothelin correlates with the extent of pulmonary hypertension in patients with chronic congestive heart failure.

BACKGROUND. Endothelin is a family of potent vasoconstrictor peptides of vascular endothelial origin. Although it has been proposed that the vasoconstrictor effects of endothelin are produced at the local vascular level, increased plasma concentration of endothelin has been identified in cardiovascular disorders. METHODS AND RESULTS. We tested whether immunoreactive endothelin-1 could be detected by radioimmunoassay in plasma of congestive heart failure patients and whether levels correlated with hemodynamic characteristics. Twenty congestive heart failure patients (New York Heart Association class II-IV) were sampled in the morning after an overnight fast, before medication. Cardiac index was decreased to 2.14 +/- 0.45 l/m/m2, and pulmonary wedge pressure was increased to 22 +/- 7 mm Hg. The ranges of pulmonary pressures were: systolic, 22-100 mm Hg, mean, 13-61 mm Hg, and diastolic, 8-42 mm Hg. The endothelin-1 level was 9.07 +/- 4.13 pg/ml (range, 4-19 pg/ml), which was increased compared with 12 normals (3.7 +/- 0.6 pg/ml; range, 2.8-4.7 pg/ml); the difference was statistically significant (p less than 0.0001). Endothelin-1 significantly correlated with pulmonary pressures (systolic, r = 0.78; mean, r = 0.80; diastolic, r = 0.77; all p less than 0.003) and pulmonary vascular resistance (r = 0.65, p less than 0.01). Endothelin-1 strongly correlated with the resistance ratio (pulmonary vascular resistance/systemic vascular resistance) (r = 0.88, p less than 0.0001). Stepwise multiple regression analysis confirmed the significance of these observations. CONCLUSIONS. Elevated immunoreactive endothelin-1 specifically correlated with the extent of pulmonary hypertension in congestive heart failure patients. Whether endothelin-1 is a regional mediator of pulmonary hypertension or a marker for its occurrence requires additional evaluation.     

Maculopapular eruption with enlarged macrophages in eight patients receiving G-CSF or GM-CSF

In the last years, granulocyte and granulocyte-macrophage colony-stimulating factors (G-CSF and GM-CSF) are being increasingly used and several cutaneous eruptions have been reported in relation to these treatments. In 1991 Horn et al. described three patients with maculopapular eruption that paralleled the time of infusion of GM-CSF. Two of the cases showed an increase in the number and size of macrophages in the biopsy specimen. Since then, several cases have been reported showing this histopathological alteration that has been considered characteristic of reaction to G-CSF or GM-CSF. Although maculopapular eruption with enlarged macrophages can appear after chemotherapy treatment, we have found that the presentation of this eruption after the beginning of cytokine treatment is suggestive of the involvement of G-CSF and GM-CSF in the eruption. We described eight cases of patients treated with G-CSF or GM-CSF that developed maculopapular eruptions with enlarged macrophages.     

Xenopus Tadpole Melanophores Are Controlled by Dark and Light and Melatonin Without Influence of Time of Day

Melanophores were studied in tadpoles of the South African clawed toad, Xenopus laevis , during the first week after hatching (stages 46–49) at 25°C. The tadpoles had melanophores with dispersed melanosomes in the light and punctate melanophores in the dark in LD12:12. The melanophores remained punctate in constant dark and the melanosomes remained dispersed in constant light. Lights-out (in the light-time of LD12:12) caused the melanophores to become punctate, which occurred more quickly than the dispersion of melanosomes, which commenced when the lights were turned on (in the dark-time of LD12:12). Melanophores with dispersed melanosomes in tadpoles (in constant light) became punctate in response to a series of melatonin concentrations (0.2–5 ng/ml) in their bathing water irrespective of the time of day melatonin was administered. An image-analysis technique for assessing melanophore responses was tested.     

Bone loss detection in rats using a mouse densitometer.

Estrogen-depletion bone-loss studies often use ovariectomized (ovx) rats and measure bone mineral density in vivo or ex vivo using DXA. Recently, a portable densitometer (PIXImus) was developed for mouse research; however, its use in rats is unclear. This study compared the ability of PIXImus and a standard densitometer (DPXL) to detect ovx-induced bone loss in rats both in vivo and ex vivo. Additionally, instrument accuracy was assessed by comparing measured bone mass with ash weight. Finally, the use of two distal femur regions of interest (ROI) to detect ovx-induced bone loss was evaluated. Twenty-three 6-month-old nulliparous female Sprague-Dawley rats were randomly assigned to sham or ovx groups. Distal femur bone mineral density was assessed at baseline and at 1 and 2 months postoperatively, using a PIXImus and DPXL densitometer. At 3 months postoperatively, all animals were killed, and ex vivo femur scans obtained. Distal femur bone loss was demonstrable by 1 month post-ovx using either densitometer. With the PIXImus, a 4-mm ROI demonstrated greater bone loss (p < 0.05) than an 8-mm ROI. Using the 4-mm ROI, similar amounts of bone loss were detected by the PIXImus and DPXL: 22.2% and 22.4%, respectively, at 2 months post-ovx. Total femur bone mineral content was overestimated by the PIXImus but highly correlated with the DPXL measurement (r = 0.988) and ash weight (r = 0.998). Given its comparability to standard DXA plus its rapid scan speed and portability, the PIXImus is useful in evaluating ovx-induced osteopenia in rats.     

Oocyte morphology predicts outcome of intracytoplasmic sperm injection

To examine the influence of cytoplasmic morphology on the success rate of intracytoplasmic sperm injection (ICSI), the morphology of 837 metaphase II oocytes was assessed after cumulus stripping. The main abnormalities detected were excessive granularity, cytoplasmic inclusions such as vacuoles, smooth endoplasmic reticulum clustering and refractile bodies. Microinjection was performed in 538 oocytes with normal cytoplasm, 142 out of 161 with excessive granularity and 112 out of 138 with cytoplasmic inclusions. Very poor oocytes were not injected. No difference was found in fertilization rate. The embryos achieved cleaved normally and a similar number of good quality embryos among the three groups was noted. The outcome of transfer of embryos derived solely from normal oocytes (group A: 72 patients, 183 embryos) was compared with those from oocytes with cytoplasmic abnormalities (group B: 34 patients, 85 embryos). In group A, 17 clinical pregnancies (24% per patient, implantation rate 10%) were established. In group B, only one clinical pregnancy (3% per patient, implantation rate 1%) was established, from the transfer of embryos derived from oocytes with homogeneous granularity of the cytoplasm. No pregnancy resulted following the transfer of embryos from eggs with cytoplasmic inclusions. The difference was statistically significant. The outcome of ICSI is dependent on the quality of the oocytes retrieved. Normal fertilization and early embryo development were achieved in oocytes with abnormal cytoplasm morphology, but the resulting embryos failed to demonstrate the same implantation potential as those derived from oocytes with normal cytoplasm.      

Comparison of the structure of human intervertebral discs in the cervical,thoracic and lumbar regions of the spine

Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4-5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3-4, T7-8 and L2-3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65 degrees) than in the thoracic and lumbar discs (about 70 degrees). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.