Perthes' disease after the age of twelve years. Role of the remaining growth

In order to define the prognostic factors in Perthes' disease in children older than 12 years, we reviewed 15 patients at the end of growth who were aged 12.1 to 14 years at presentation. The patients with the worst long-term prognosis (Stulberg class V) were compared with the others for age, skeletal maturity and remaining growth (Oxford method), as well as Catterall and Waldenström classifications at presentation. A significant difference (p = 0.001) was found for remaining growth (25% in Stulberg class V and 35% in the others) and also for the results at the end of growth when the remaining growth was over 30%, since this allowed sufficient time for reformation and remodelling of the femoral head.

Perthes’ disease after the age of twelve years

In order to define the prognostic factors in Perthes’ disease in children older than 12 years, we reviewed 15 patients at the end of growth who were aged 12.1 to 14 years at presentation. The patients with the worst long-term prognosis (Stulberg class V) were compared with the others for age, skeletal maturity and remaining growth (Oxford method), as well as Catterall and Waldenström classifications at presentation. A significant difference (p = 0.001) was found for remaining growth (25% in Stulberg class V and 35% in the others) and also for the results at the end of growth when the remaining growth was over 30%, since this allowed sufficient time for reformation and remodelling of the femoral head.

Formin defines a large family of morphoregulatory genes and functions in establishment of the polarising region

Formin was originally isolated as the gene affected by the murine limb deformity (ld) mutations, which disrupt the epithelial-mesenchymal interactions regulating patterning of the vertebrate limb autopod. More recently, a rapidly growing number of genes with similarity to formin have been isolated from many different species including fungi and plants. Genetic and biochemical analysis shows that formin family members function in cellular processes regulating either cytokinesis and/or cell polarisation. Another common feature among formin family members is their requirement in morphogenetic processes such as budding and conjugation of yeast, establishment of Drosophila oocyte polarity and vertebrate limb pattern formation. Vertebrate formins are predominantly nuclear proteins which control polarising activity in limb buds through establishment of the SHH/FGF-4 feedback loop. Formin acts in the limb bud mesenchyme to induce apical ectodermal ridge (AER) differentiation and FGF-4 expression in the posterior AER compartment. Finally, disruption of the epithelial-mesenchymal interactions controlling induction of metanephric kidneys in ld mutant embryos indicates that formin might function more generally in transduction of morphogenetic signals during embryonic pattern formation.

Gli3 (Xt) and formin (ld) participate in the positioning of the polarising region and control of posterior limb-bud identity

During initiation of limb-bud outgrowth in vertebrate embryos, the polarising region (limb-bud organizer) is established upon activation of the Sonic Hedgehog (SHH) signaling molecule at the posterior limb-bud margin. Another hallmark of establishing anteroposterior limb-bud identities is the colinear activation of HoxD genes located at the 5′ end of the cluster (5′HoxD genes). The unique and shared functions of Gli3 and formin in these determinative events were genetically analyzed using single and double homozygous Extra-toes (Xt; disrupting Gli3) and limb deformity (ld; disrupting formin) mouse embryos. Analysis of the limb skeletal phenotypes reveals genetic interaction of the two genes. In addition to loss of digit identity and varying degrees of polydactyly, proximal skeletal elements are severely shortened in Xt;ld double homozygous limbs. The underlying molecular defects affect both establishment of the polarising region and posterior limb-bud identity. In particular, the synergism between Gli3- and formin-mediated mesenchyme-AER interactions positions the SHH signaling center at the posterior limb-bud margin. The present study shows that establishment and positioning of the polarising region is regulated both by restriction of Shh through Gli3 and its positive feedback regulation through formin. Concurrently, Gli3 functions independently of formin during initial posterior nesting of 5′HoxD domains, whereas their subsequent distal restriction and anterior expansion depends on genetic interaction of Gli3 and formin.

[Computer graphic analysis of the three dimensional deformities of scoliotic vertebrae]

GOAL

A computer graphics method that permits the reconstruction, visualization and measure of the vertebral deformities of the scoliotic spine is presented.

MATERIALS

Medical imaging techniques utilizing computerized tomography is at the foundation of the reconstruction technique. The studied morphometric parameters are: 1) vertebral body wedging, 2) transverse and spinous process orientation and dimensions and 3) bilateral variation of pedicular dimensions.

RESULTS

The reconstructed specimen showed the usefulness of this technique for visualizing and measuring vertebral deformities. Preliminary results seem to be in agreement with the literature concerning the deformities of scoliotic vertebrae.

CONCLUSION

This tool will be useful in morphometric investigations for the evaluation of the deformations of scoliotic vertebrae.

Impaired cerebral cortex development and blood pressure regulation in FGF-2-deficient mice

Fibroblast growth factor-2 (FGF-2) has been implicated in various signaling processes which control embryonic growth and differentiation, adult physiology and pathology. To analyze the in vivo functions of this signaling molecule, the FGF-2 gene was inactivated by homologous recombination in mouse embryonic stem cells. FGF-2-deficient mice are viable, but display cerebral cortex defects at birth. Bromodeoxyuridine pulse labeling of embryos showed that proliferation of neuronal progenitors is normal, whereas a fraction of them fail to colonize their target layers in the cerebral cortex. A corresponding reduction in parvalbumin-positive neurons is observed in adult cortical layers. Neuronal defects are not limited to the cerebral cortex, as ectopic parvalbumin-positive neurons are present in the hippocampal commissure and neuronal deficiencies are observed in the cervical spinal cord. Physiological studies showed that FGF-2-deficient adult mice are hypotensive. They respond normally to angiotensin II-induced hypertension, whereas neural regulation of blood pressure by the baroreceptor reflex is impaired. The present genetic study establishes that FGF-2 participates in controlling fates, migration and differentiation of neuronal cells, whereas it is not essential for their proliferation. The observed autonomic dysfunction in FGF-2-deficient adult mice uncovers more general roles in neural development and function.

[A protocol of in vivo 3D experimental evaluation of global posture and motion of the spine]

PURPOSE

The aim of his study was to assess 3D global posture and movement of body segments, especially for scoliotic subjects. As scoliosis is a three-dimensional deformity, it needs three-dimensional evaluation and correction, but there is no mean today to get 3D dynamic examination of the whole body.

MATERIAL AND METHODS

Using opto-electronic methods, an experimental protocol was established to compare the pre- and post-operative results of treatment. Firstly, the reliability of the protocol was tested in healthy adult subject. Secondly, a reference group of 15 healthy teenagers was analysed Besides, first scoliotic subject in pre- and post-operative situations were followed. The markers fixed on the skin allowed us to calculate the position of the head, the pelvic, the shoulders and the spinal axis, during a static trial and motions.

RESULTS

The reliability of the protocol was satisfactory (standard deviation (s) < 5.4 degrees in a flexion movement). The inter-subject variability was greater for the position of the head than for the pelvis, the shoulders or the spinal axis. The scoliotic patient showed a straightening of the whole body in the three anatomic planes. One month after treatment, the range of motion were reduced (+13.8 degrees for the pelvic flexion during a flexion movement), but six months after surgery they were greater than before (+14.7 degrees).

CONCLUSION-DISCUSSION

Many systems have been proposed to measure the motion of the trunk, but they were not three-dimensional. The opto-electronic method is a non invasive, external and dynamic system.

A GR-motif functions in nuclear accumulation of the large FGF-2 isoforms and interferes with mitogenic signalling

Nuclear translocation has been documented for members of the fibroblast growth factor (FGF) family in addition to their roles as extra-cellular signalling molecules. Fusing different parts of the chicken FGF-2 open reading frame to pyruvate kinase shows that direct nuclear accumulation is mediated by the amino-termini of the two leucine initiated FGF-2 isoforms (Leu-isoforms; 21.5 and 20.0 kDa). An evolutionarily conserved glycine-arginine (GR)-motif is present in the 21.5 kDa Leu-isoform and a shorter GR-repeat in the 20.0 kDa Leu-isoform, whereas no such repeats are present in the 18.5 kDa FGF-2 isoform (Met-isoform). Expression in NIH3T3 fibroblasts shows that the 21.5 kDa Leu-isoform is predominantly nuclear, whereas the Met-isoform is predominantly cytoplasmic. Most importantly, insertion of the GR-motif into the Met-isoform results in a protein with characteristics similar to the Leu-isoforms, as shown by nuclear accumulation of the chimeric MGR-protein. Furthermore, only NIH3T3 fibroblasts expressing the Met-isoform proliferate under serum starvation conditions, whereas cells expressing either the MGR- or Leu-isoforms stay growth arrested. These studies show that the GR-signal mediates nuclear translocation of endogenous Leu-isoforms and blocks their mitogenic activity.

Development and testing of a measure of perceived caregiver rewards in adults

Assessment of the rewards of caregiving is pertinent to a holistic view of the caregiving experience and design of health promotion interventions for caregivers. Few measures of caregiver positive appraisals exist. This paper describes the development and pilot testing of the Picot Caregiver Rewards Scale (PCRS) for adult caregivers. Derived from the choice and social exchange theory, caregiver interviews, and literature, 25 items compose the scale. Psychometric testings of the PCRS were conducted in a nonrandom sample of 83 Black female caregivers and a random sample of 256 Black and White female and male caregivers. Alphas of .83 and .88 demonstrated acceptable internal consistency of the revised 16-item PCRS. Construct validity was demonstrated by support of hypothesized relationships with caregiving demands, palliative coping, depression, and caregiver burden, as well as confirmatory factor analysis. Further psychometric study of the PCRS is recommended.

Rearrangements of the cytoskeleton and cell contacts induce process formation during differentiation of conditionally immortalized mouse podocyte cell lines

Mature podocytes are among the most complex differentiated cells and possess a highly branched array of foot processes that are essential to glomerular filtration in the kidney. Such differentiated podocytes are unable to replicate and culturing of primary podocytes results in rapid growth arrest. Therefore, conditionally immortalized mouse podocyte clones (MPC) were established, which are highly proliferative when cultured under permissive conditions. Nonpermissive conditions render the majority of MPC cells growth arrested within 6 days and induce many characteristics of differentiated podocytes. Both proliferating and differentiating MPC cells express the WT-1 protein and an ordered array of actin fibers and microtubules extends into the forming cellular processes during differentiation, reminiscent of podocyte processes in vivo. These cytoskeletal rearrangements and process formation are accompanied by the onset of synaptopodin synthesis, an actin-associated protein marking specifically differentiated podocytes. In addition, focal contacts are rearranged into an ordered pattern in differentiating MPC cells. Most importantly, electrophysiological studies demonstrate that differentiated MPC cells respond to the vasoactive peptide bradykinin by changes in intracellular calcium concentration. These results suggest a regulatory role of podocytes in glomerular filtration. Taken together, these studies establish that conditionally immortalized MPC cells retain a differentiation potential similar to podocytes in vivo. Therefore, the determinative steps of podocyte differentiation and process formation are studied for the first time using an inducible in vitro model.

Dorso-ventral limb polarity and origin of the ridge: on the fringe of independence?

Molecular and developmental studies of limb pattern formation have recently gained widespread attention. The fact that vertebrate limbs are amenable to both genetic and embryological manipulations has established this model system as a valuable paradigm for studying vertebrate development. Limb buds are polarised along all three major axes and the establishment of the dorso-ventral (DV) polarity is dependent upon cues localised in the trunk, where a DV ectodermal interface is produced by confrontation of dorsal and ventral identities. By analogy to Drosophila imaginal disc development, this interface has been proposed to determine and position an ectodermal organising centre, the Apical Ectodermal Ridge (AER), controlling limb bud outgrowth. Recent fate mapping studies and studies of genes regulating DV limb polarity, AER formation and differentiation suggest, however, that DV patterning and AER induction, though coordinately regulated during limb bud outgrowth, may early on be more dissociated than expected.

Molecular interaction between limb deformity proteins (formins) and Src family kinases

Ld proteins (formins) are encoded by the limb deformity (ld) gene and define a family of related gene products regulating establishment of embryonic polarity. In this study we establish that chicken and murine Ld proteins interact directly with Src family kinases (c-Src and c-Fyn). Specific binding is mediated by the proline-rich domain present in Ld proteins and the ligand binding surface of the Src SH3 domain. Co-immunoprecipitation of Ld and c-Src proteins from transfected cells shows that these proteins associate in vivo. Immunolocalization and biochemical fractionation of fibroblasts confirms the predominant nuclear localization of Ld proteins, but unexpectedly identifies a population of Ld proteins associated to cellular membranes. This population of Ld proteins co-localizes with membrane-associated c-Src proteins at both plasma and perinuclear membranes. These studies indicate that the morphoregulatory Ld proteins interact with signal transduction cascades by association to membrane-bound Src family kinases.

AltFGF-2, a novel ER-associated FGF-2 protein isoform: its embryonic distribution and functional analysis during neural tube development

A novel fibroblast growth factor-2 (FGF-2) protein isoform, called altFGF-2, is expressed abundantly during chicken embryogenesis. The amino-terminal domain of the 21.5-kDa altFGF-2 protein diverges completely from the other three FGF-2 proteins due to alternative splicing of their first coding exons. Furthermore, the altFGF-2 protein, in contrast to FGF-2 proteins, is targeted predominantly to the endoplasmic reticulum. In chicken embryos, altFGF-2 and FGF-2 proteins are differentially distributed in several mesodermal structures including developing limbs and kidneys. All four FGF-2 protein isoforms are also expressed in the developing neural tube from early neural plate stages onward. In contrast to FGF-2 proteins, the altFGF-2 isoform is distributed in a dynamic, spatially restricted pattern in notochord and ventral neural tube (floor plate and motor neurons) during specification of neuronal populations. To study the possible shared or differential signaling functions of chicken altFGF-2 and FGF-2 gene products, they were ectopically expressed in the dorsal neural tube aspect of transgenic mouse embryos. Dorsal expression of altFGF-2, but not FGF-2 gene products, induced alteration of neural tube morphology in a significant fraction of mouse embryos (25%). However, no alterations of dorsoventral (d/v) neural tube polarity were detected, indicating that altFGF-2 and FGF-2 gene products either function as permissive cofactors or regulate neural tube growth without affecting establishment of its primary d/v polarity.

[Extra osseous tumors of the spine in children and adolescents. Spinal complications]

PURPOSE OF THE STUDY

The delay in diagnosis of spinal tumors is not rare. The chief complaint may include pain, walking disability, and spinal or limb deformities. The purpose of our study is to analyze the spinal deformities associated with non osseous intraspinal tumors, to assess the complications of treatment, and to set out a preventive protocol.

MATERIALS

We reviewed retrospectively 40 consecutive cases of non osseous intraspinal tumors treated between 1972 and 1991. There were 32 intradural, 2 extradural, and 6 intra and extradural combined tumors. At the first consultation, the age ranged between 4 months and 15 years, and only 16 patients showed neurologic deficit. Spinal deformity existed in 9 patients, 7 of which had no neurologic deficit. All the tumors were treated surgically. Laminectomy was done in 28 cases, and osteoplastic laminotomy in 12 cases. The number of levels included in the laminectomy ranged from 3 to 18. Bilateral arthrectomy at least at one level was undertaken in 15 cases. A postoperative brace was worn in all cases for an average period of 4 months. An adjuvant radiotherapy was undertaken in 12 cases for an incomplete resection.

METHODS

The incidence and pattern of spinal deformity was assessed before tumor treatment and ultimately after laminectomy or osteoplastic laminotomy (or laminoplasty).

RESULTS

Among the 9 cases with preexisting spinal deformity, the curve magnitude increased after laminectomy in 4. A kyphotic, kyphosoliotic or scoliotic deformity developed in 18 cases after surgery for tumor resection. Among these 18 patients, only one had had an adequate osteoplastic laminotomy. The treatment of spinal deformities was surgical in 12 cases, and done by either posterior or anterior and posterior combined arthrodesis.

DISCUSSION

Spinal deformity may be the main complaint of a patient who has intraspinal tumor. Prevention of postlaminectomy spinal deformity is mandatory, and could be done by osteoplastic laminotomy and the use of a brace during a minimum period of 4 to 6 months after surgery.

CONCLUSION

Diagnosis of intraspinal tumors in children and adolescents should be done early, and laminoarthrectomy should be replaced by osteoplastic laminotomy.

Differential effects of retinoic acid and a retinoid antagonist on the spatial distribution of the homeoprotein Hoxb-7 in vertebrate embryos

An antibody raised against the recombinant Xenopus laevis Hoxb-7 protein (López and Carrasco [1992] Mech. Dev. 36:153-164) recognizes the 30 kDa translation product of the Hoxb-7 gene in X. laevis and the cognate nuclear protein in chicken embryos. The X. laevis Hoxb-7 protein was expressed maternally and zygotically. Treatment of X. laevis and chicken embryos with either all-trans retinoic acid (RA) or the retinoid antagonist Ro 41-5253 (Ro; Apfel et al. [1992] Proc. Natl. Acad. Sci. U.S.A. 89:7129-7133) during early development induced malformations of the neural tube and complementary changes in the expression domain of the homeoprotein Hoxb-7. Treatment of X. laevis embryos with retinoic acid during gastrulation induced an anterior shift of the Hoxb-7 expression domain and was correlated with an enlargement of rhombomere r7. In addition to a reduction in rhombomere numbers and of forebrain size, various malformations involving all three germ layers were observed. Treatment of X. laevis embryos with the antagonist Ro before or during gastrulation caused a progressive reduction of the Hoxb-7 domain and also dose-dependent malformations of all three germ layers. RA or Ro treatment of chicken embryos from the beginning of gastrulation caused changes of the Hoxb-7 expression domain very similar to those observed in X. laevis. In particular, either a dose-dependent loss of the Hoxb-7 protein in the neural tube or an ectopic expression in the forebrain region was observed. The results of this study indicate that endogenous retinoids regulate the spatial expression of homeobox-containing genes in vertebrates.