In utero Exposure to Anesthetics Alters Neuronal Migration Pattern in Developing Cerebral Cortex and Causes Postnatal Behavioral Deficits in Rats.

During fetal development, cerebral cortical neurons are generated in the proliferative zone along the ventricles and then migrate to their final positions. To examine the impact of in utero exposure to anesthetics on neuronal migration, we injected pregnant rats with bromodeoxyuridine to label fetal neurons generated at embryonic Day (E) 17 and then randomized these rats to 9 different groups receiving 3 different means of anesthesia (oxygen/control, propofol, isoflurane) for 3 exposure durations (20, 50, 120 min). Histological analysis of brains from 54 pups revealed that significant number of neurons in anesthetized animals failed to acquire their correct cortical position and remained dispersed within inappropriate cortical layers and/or adjacent white matter. Behavioral testing of 86 littermates pointed to abnormalities that correspond to the aberrations in the brain areas that are specifically developing during the E17. In the second set of experiments, fetal brains exposed to isoflurane at E16 had diminished expression of the reelin and glutamic acid decarboxylase 67, proteins critical for neuronal migration. Together, these results call for cautious use of anesthetics during the neuronal migration period in pregnancy and more comprehensive investigation of neurodevelopmental consequences for the fetus and possible consequences later in life.

Noninvasive assessment of liver fibrosis with acoustic radiation force impulse imaging: increased liver and splenic stiffness in patients with liver fibrosis and cirrhosis.

PURPOSE: To evaluate acoustic radiation force impulse imaging (ARFI) of the liver and spleen as a new method for the noninvasive assessment of liver fibrosis (LF). MATERIALS AND METHODS: Three groups of 58 examinees were studied: (A) 20 healthy volunteers; (B) 18 patients with chronic viral hepatitis (CVH) B or C having liver fibrosis stages F 1 - 4 (assessed by liver biopsy; Ishak classification); and (C) 20 patients with liver cirrhosis (LC). All participants were examined using the Siemens ACUSON S 2000 Ultrasound Virtual Touch Tissue Quantification system. Ten measurements were performed on both liver lobes and three measurements on the spleen, and the obtained mean values (shear wave velocities [SWV] expressed in m/s) were compared between the groups. In 20 patients the splenic artery pulsatility index (SAPI) was also measured and correlated to the liver and splenic ARFI and histological stage of LF. RESULTS: Hepatic ARFI measurements demonstrated a significant correlation to LB results (Spearman's ρ = 0.766; ρ < 0.001) and SWV cut-off values of 1.3 (AUC 0.96) and 1.86 (AUC 0.99) could reliably differentiate between healthy (A) and non-cirrhotic CVH (B), as well as between non-cirrhotic CVH (B) and LC (C). Splenic SWV cut-off value of 2.73 (AUC 0.82) could differentiate between the patients with LC and non-cirrhotic CVH. A significant correlation was also observed between the SAPI and liver ARFI results (ρ = 0.56; p = 0.013). CONCLUSION: The hepatic and splenic SWV measured by ARFI increase with the LF stage, and the hepatic SWV correlate well with SAPI. This new technology enables simultaneous morphological, Doppler and elastometric examinations and might improve the accuracy of noninvasive liver fibrosis assessment.

Activated T lymphocytes suppress osteoclastogenesis by diverting early monocyte/macrophage progenitor lineage commitment towards dendritic cell differentiation through down-regulation of receptor activator of nuclear factor-kappaB and c-Fos.

Activated T lymphocytes either stimulate or inhibit osteoclastogenesis from haematopoietic progenitors in different experimental models. To address this controversy, we used several modes of T lymphocyte activation in osteoclast differentiation--mitogen-pulse, anti-CD3/CD28 stimulation and in vivo and in vitro alloactivation. Osteoclast-like cells were generated from non-adherent immature haematopoietic monocyte/macrophage progenitors in murine bone-marrow in the presence of receptor activator of nuclear factor (NF)-kappaB ligand (RANKL) and monocyte-macrophage colony-stimulating factor (M-CSF). All modes of in vivo and in vitro T lymphocyte activation and both CD4(+) and CD8(+) subpopulations produced similar inhibitory effects on osteoclastogenesis paralleled by enhanced dendritic cell (DC) differentiation. Osteoclast-inhibitory effect was associated with T lymphocyte activation and not proliferation, and could be replaced by their culture supernatants. The stage of osteoclast differentiation was crucial for the inhibitory action of activated T lymphocytes on osteoclastogenesis, because the suppressive effect was visible only on early osteoclast progenitors but not on committed osteoclasts. Inhibition was associated specifically with increased granulocyte-macrophage colony-stimulating factor (GM-CSF) expression by the mechanism of progenitor commitment toward lineages other than osteoclast because activated T lymphocytes down-regulated RANK, CD115, c-Fos and calcitonin receptor expression, and increased differentiation towards CD11c-positive DC. An activated T lymphocyte inhibitory role in osteoclastogenesis, confirmed in vitro and in vivo, mediated through GM-CSF release, may be used to counteract activated bone resorption mediated by T lymphocyte-derived cytokines in inflammatory and immune disorders. We also demonstrated the importance of alloactivation in osteoclast differentiation and the ability of cyclosporin A to abrogate T lymphocyte inhibition of osteoclastogenesis, thereby confirming the functional link between alloreaction and bone metabolism.

Alteration of newly induced endochondral bone formation in adult mice without tumour necrosis factor receptor 1.

Tumour necrosis factor (TNF)-alpha, a major proinflammatory cytokine, exerts its role on bone cells through two receptors (TNFR1 and TNFR2). TNFR1, but not TNFR2, is expressed by osteoblasts and its function in bone formation in vivo is not fully understood. We compared in vivo new bone formation in TNFR1-deficient (TNFR1(-/-)) mice and wild-type mice, using two models of bone formation: intramembranous ossification following tibial marrow ablation and endochondral ossification induced by bone morphogenetic protein (BMP)-2. Intramembranous osteogenesis in TNFR1(-/-) mice did not differ from the wild-type mice either in histomorphometric parameters or mRNA expression of bone-related markers and inflammatory cytokines. During endochondral osteogenesis, TNFR1(-/-) mice formed more cartilage (at post-implantation day 9), followed by more bone and bone marrow (at day 12). mRNAs for BMP-2, -4 and -7 were increased during the endochondral differentiation sequence in TNFR1(-/-) mice. The expression of receptor activator of NF-kappa B ligand (RANKL) and receptor activator of NF-kappa B (RANK), as assessed by quantitative reverse transcription polymerase chain reaction (RT-PCR), was also increased significantly during endochondral ossification in TNFR1(-/-) mice. In conclusion, signalling through the TNFR1 seems to be a negative regulator of new tissue formation during endochondral but not intramembranous osteogenesis in an adult organism. BMPs and RANKL and its receptor RANK may be involved in the change of local environment in the absence of TNFR1 signalling.

Persistent cervical intersegmental artery and aortic arch coarctation.

A 15-year-old girl presented with upper extremity hypertension and continuous precordial murmur. Arteriography revealed aortic coarctation proximal to the origin of the left subclavian artery. An anomalous artery originated from the aortic arch, between the left common carotid artery and the stenosis. It ascended cranially and filled an angiomatous vascular formation on the left side of the neck. The "angioma" drained into the left subclavian artery. The embryological explanation of the described anomaly is difficult, but probably related to hemodynamic alterations following the prestenotic increase in blood pressure. This may have impaired the obliteration of cervical intersegmental arteries, resulting in the persistence of one of the first three intersegmental arteries as the anomalous branch of the aortic arch. The angiomatous vascular formation in the neck could be the consequence of altered development of anastomoses between the muscular twigs of both vertebral and deep cervical artery. The vessel draining the vascular formation was probably the thyrocervical trunk. Since there were no overt collateral channels or signs of left ventricular hypertrophy by electrocardiography and echocardiography, it seems that the aberrant collateral flow was hemodynamically significant and reduced the afterload on the myocardium. Although the pattern of collateral flow in our case might be considered extremely rare, it is important in preoperative planning and interpretation of imaging studies.

Appointment of statistical editor and quality of statistics in a small medical journal.

AIM: To test if the appointment of a statistical editor improves the quality of manuscripts published in a small general medical journal. METHODS: Retrospective review of all manuscripts containing statistical data published in the Croatian Medical Journal between 1992 and 2000 (n=241). Statistical analysis and its presentation were assessed by a single observer. RESULTS: Before the appointment of statistical editor in 1996, 97 manuscripts with statistical data were published. Statistics was not satisfactory in 52 (54%) of them, including 26 definite errors in analysis and 43 in presentation. After the appointment of statistical editor, 144 manuscripts containing statistical data were published. Statistics was not satisfactory in 91 (63%) of them, with 51 definite errors in analysis and 69 in presentation. Out of 144 manuscripts, the editor-in-chief sent out 30 (21%) for statistical review. Statistics was not satisfactory in 25 of them, including 11 definite errors in analysis and 17 in presentation. Statistical editors comments improved three manuscripts. If the authors had acknowledged all statistical editors suggestions, 9 more manuscripts would have been improved. Statistical editor had a total of 195 comments on 30 published manuscripts. Most numerous were the comments concerning the presentation of the statistical analysis (51%), followed by the general comments (26%), comments on analysis (11%), study design (8%), and interpretation (4%). CONCLUSION: Appointment of a statistical editor is not a guarantee of improvement of statistics in small journals. Other measures are necessary, including strict editorial policy on statistical review, monitoring of revised manuscript versions, and enrollment of formally trained biostatisticians.

Cellular and molecular interactions between immune system and bone.

Functional interdependence between immune and bone systems is reflected in a number of regulatory molecules acting on the cells of both systems and common precursors for bone and immune cells. Therefore, the disturbances of the immune system may affect bone metabolism, and vice versa. This review addresses the roles of two major immune cell populations, T and B lymphocytes, in the regulation of bone metabolism. Experimental models and human diseases demonstrated that T lymphocytes may produce many bone cell regulatory cytokines, including two essential stimulators of osteoclastogenesis: receptor for activation of nuclear factor kappa b (NF-kappa B) (RANK) ligand (RANKL) and macrophage colony-stimulating factor. The effect of T lymphocytes on osteoclastogenesis may be both stimulatory and inhibitory, and depends on the activation stage and pattern of cytokine production. We showed that acute removal of T lymphocytes stimulated osteoclast differentiation in vitro and enhanced new cartilage and bone formation at non-osseous sites in vivo. B lymphocytes may be even more closely related to bone cells, as B lymphopoiesis requires an intimate contact with osteoblastic/stromal cells, and estrogens, powerful regulators of bone mass, are also involved in the differentiation of the B lymphocyte lineage. Also, B lymphocyte progenitors may give rise to functional osteoclasts. Both B and T lymphocytes may act through the RANKL/RANK/osteoprotegerin cytokine system, which has been independently discovered within immune and bone systems. These cytokines have crucial roles in the development and function of osteoclasts, dendritic cells, and T and B lymphocytes, as well as in the thymus and lymph node organogenesis. The cytokines produced by immune cells may affect bone cell function and vice versa, but the full complexity of these interactions awaits further investigation.

Weekly quizzes in extended-matching format as a means of monitoring students' progress in gross anatomy.

We compared weekly quizzes in extended-matching format with multiple-choice questions and oral examinations as means of monitoring students' progress in gross anatomy. Students' performance on 19 weekly oral examinations or 10-question quizzes based on extended-matching or multiple-choice formats were correlated with their success on 3 interim examinations and the final comprehensive examination. The Kuder-Richardson formula 20, an estimate of precision of the test, was 0.64 for extended-matching quizzes. Students' performance on interim examinations did not differ significantly. There was a significant correlation between students' mean scores on weekly quizzes and mean scores on interim examinations in both the extended-matching (r = 0.516) and multiple-choice group (r = 0.823). The mean grades (ranging from 2 to 5) on the final exam, based on understanding of anatomical concepts and their application in clinical practice, were significantly higher in extended-matching group (4.8) than in the multiple-choice (4.1) and orally examined groups (3.9) (p < 0.05). We conclude that extended-matching quizzes were at least as effective as multiple-choice quizzes and oral examinations and may be better for acquiring synthetic understanding of anatomical concepts especially in combination with other means of knowledge assessment. We recommend them as a reliable and objective means of monitoring students' performance during a gross anatomy course.

Role of B lymphocytes in new bone formation.

Although there may be a close relationship between B lymphocytes and osteoclasts, or bone resorbing cells, little is known about the role of B lymphocytes in bone formation. We compared in vivo new bone induction in mice homozygous for the B-cell deficient (microMT) gene knockout, which lack functional B lymphocytes, with bone induction in control wild-type (C57BL/6) mice. Our comparison used two models of new bone induction in vivo: endochondral osteoinduction by subcutaneous implantation of recombinant human bone morphogenetic protein (rhBMP-2) and osteogenic regeneration after tibial bone marrow ablation. The expression of bone-specific proteins (bone sialoprotein, osteopontin, and osteocalcin) and inflammatory/immunomodulatory cytokines (interleukin-1alpha and -1beta, interleukin-6, and tumor necrosis factor-alpha) was assessed by Northern blot analysis or reverse transcription-polymerase chain reaction, respectively. Ossicles induced by rhBMP-2 were larger in volume and mass in microMT knockout mice, but relative volumes of the newly induced bone, cartilage, and bone marrow were similar in the two groups. Six days after tibial bone marrow ablation, microMT knockout mice resorbed the initial blood clot faster and formed more trabecular bone, paralleled by greater levels of bone sialoprotein mRNA than in the wild-type mice. microMT knockout and wild-type mice also differed in the expression pattern of inflammatory/immunomodulatory cytokines during the development of the newly induced bone, suggesting that a genetic lack of B lymphocytes may create a change in the immunological milieu at the site of new bone induction, which stimulates the initial accumulation and proliferation of mesenchymal progenitor.

Genetic variability of new bone induction in mice.

We studied differences in ectopic osteoinduction in eight mouse inbred strains and an outbred strain. Antigen-extracted autolyzed rat bone gelatin was implanted under hind limb muscle fascia of 12-week-old males, and new bone formation was morphologically assessed on serial sections. Four weeks after implantation, less than half of the implants from CBA/J, A/J, BALB/cJ, and C3Hf/Bu mice showed induction of only cartilage. New cartilage was observed in all, and bone and bone marrow in 80% of the implants from AKR/J, C57BL/6J, DBA/2J, and RFM/Rij mice. Volume of the newly formed tissue ranged from 1.3% of the old matrix in A/J strain to 74.6% in DBA/2J strain. Outbred CD1 mice showed only weak cartilage induction. The "good" responders differed among themselves in the volume and type of newly induced tissue: DBA/2J, RFM/Rij, and AKR/J mice had a similar ratio of new bone and cartilage and abundant bone marrow, whereas the predominant newly induced tissue in C57Bl/6J mice was cartilage. The pattern of the expression of BMP-2, -4, and -7, alkaline phosphatase, osteocalcin, interferon-gamma, and granulocyte-macrophage colony-stimulating factor, measured by reverse transcriptase polymerase chain reaction, did not correlate with the type and the quantity of the newly induced tissue. Our results show that adult mice of inbred strains differ not only in the peak bone mass and morphology, but also ability to form new bone after an osteoinductive stimulus. Ectopic osteoinduction may be a useful in vivo model to investigate genetic determinants of endochondral osteogenesis, especially its immunological component.