Compressive Strength of Iliac Bone ECM Is Not Reduced in Osteogenesis Imperfecta and Increases With Mineralization

Osteogenesis imperfecta (OI) is an inheritable, genetic, and collagen-related disorder leading to an increase in bone fragility, but the origin of its “brittle behavior” is unclear. Because of its complex hierarchical structure, bone behaves differently at various length scales. This study aims to compare mechanical properties of human OI bone with healthy control bone at the extracellular matrix (ECM) level and to quantify the influence of the degree of mineralization. Degree of mineralization and mechanical properties were analyzed under dry conditions in 12 fixed and embedded transiliac crest biopsies (control n = 6, OI type I n = 3, OI type IV n = 2, and OI type III n = 1). Mean degree of mineralization was measured by microcomputed tomography at the biopsy level and the mineral-to-matrix ratio was assessed by Raman spectroscopy at the ECM level. Both methods revealed that the degree of mineralization is higher for OI bone compared with healthy control. Micropillar compression is a novel technique for quantifying post-yield properties of bone at the ECM level. Micropillars (d = 5 μm, h = 10 μm) were fabricated using focused ion beam milling and quasi-statically compressed to capture key post-yield properties such as ultimate strength. The qualitative inspection of the stress–strain curves showed that both OI and healthy control bone have a ductile response at the ECM level. The quantitative results showed that compressive strength is not reduced in OI bone and is increasing with OI severity. Nanoindentation measurements revealed that OI bone tends to have a higher Young's modulus, hardness, and dissipated energy compared with healthy bone. Micropillar strength and indentation modulus increased linearly and significantly (p < .0001) with mineral-to-matrix ratio. In conclusion, this study indicates that compressive mechanical properties of dry OI bone at the iliac crest are not inferior to healthy control at the ECM level and increase with mineralization. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

The “jerky dystonic unsteady hand”: A delayed motor syndrome in posterior thalamic infarctions

We report the cases of three patients with a thalamic infarct in the territory of the posterior choroidal artery involving the posterior thalamic nuclei. These patients developed delayed complex hyperkinetic motor syndromes, associating ataxia, tremor, dystonia, myoclonus and chorea, which we call the jerky dystonic unsteady hand. One patient had a severe myoclonic and ataxicdystonic choreoathetosis; another showed a so-called rubral tremor (myoclonic ataxia with resting, action, and wing-beating tremor) with dystonia; and the third one had a dystonic and ataxic hand with intermittent mild action myoclonus. All of them had sensory dysfunction; two had also presented with a painful Dejérine-Roussy syndrome. All had CT or MRI-proven infarcts in the territory of the posterior cerebral artery involving the posterior choroidal territory with an abnormal signal in the posterior area of the thalamus (pulvinar nucleus) but sparing the other thalamic, subthalamic and midbrain structures. These delayed myoclonic complex hyperkinetic syndromes have not been reported before, and we did not observe them in other topographic forms of thalamic infarcts. They may thus represent a new entity of movement disorders due to lesions in the posterior thalamic nuclei, with specificity for posterior choroidal artery infarcts.     

Testicular degeneration in three patients with the persistent müllerian duct syndrome

The presistent Müllerian duct syndrome, characterized by the presence of uterus and tubes in males, is a familial disorder due to defects of synthesis or action of anti-Müllerian hormone, a Sertoli cell glycoprotein responsible for the regression of Müllerian derivatives in normal male fetuses. Patients are normally virilized and testicular production of testosterone is normal. Both testes my be cryptorchild; alternatively, one may be descended into the inguinal canal or scrotum, together with the Müllerian derivatives, a condition known as hernia uteri inguinalis. We have recently observed three patients affected by the presistent Müllerian duct syndrome who experienced progressive degeneration of testicular tissue. In two, functional testicular tissue was still present some months after birth, but deteriortated progressively later. In one patient, testicular tissue was already absent at birth, but the normal virilization of external genitalia indicated that testicular degeneration must have occurred lat during fetal life, after the expected time of regression of male Müllerian ducts.Conclusion The high incidence of degeneration of testicular tissue in the presistent Müllerian duct syndrome could be indirectly linked to anatomical abnormalities which could favour testicular torsion, known to induce testicular regression.     

Chain transfer by addition-fragmentation mechanism, 5 Investigation of the chain transfer activity of several ethyl 2-(substituted)cinnamates

A variety of ethyl 2-(substituted)cinnamates

1 Systematic name: ethyl 3-phenyl-2-(substituted)propenoate.

were synthesized and added to vinylic monomer polymerizations. These olefins are activated towards free radical addition and contain a homolytic leaving group in the allylic position. Thus, they exhibit chemical transfer properties in free radical polymerization. The compounds studied include bromide, iodide, sulfone, mercaptan and peroxide derivatives. Cinnamic iodide, however, exhibits degradative chain transfer activity. These compounds have an advantage over simple thiols in that they permit a good control of molar mass by an addition-fragmentation mechanism involving difunctionalization of the resulting telomers. The methods of synthesis of ethyl 2-(substituted)cinnamates are discussed through the nucleophilic substitution of various anions toward the allylic bromo derivative prepared from ethyl 2-(α-hydroxybenzyl)propenoate.     

Cancer mortality among sub-Saharan African migrants in France

Not only are there few data on sub-Saharan migrant populations, but relatively little information is available on cancer patterns in Africa. This report presents cancer mortality patterns among the 290,000 sub-Saharan African migrants in France. Risks of mortality from different cancers in migrants born in West, Central, East, and Other parts of Africa have been compared with that observed in the local-born population, using mortality data from the period 1979–85 and population data from the 1982 French census. Relative risks were adjusted for important confounding factors such as social class and area of residence. Compared with natives, overall mortality from cancer is lower in sub-Saharan African migrants. Higher cancer mortality risks, however, are observed among males for several sites: liver in Central and West Africans; bladder in West Africans; and non-Hodgkin's lymphoma in Other African migrants. For females, risks were elevated for nasopharyngeal cancers in Other African and liver in West African migrants. The results are, for the most part, consistent with the few available data on cancer patterns in Africa, and with the patterns observed in African migrants to England and Wales (UK).This work was undertaken during the tenure of a Research Training Fellowship awarded to Dr Bouchardy by the International Agency for Research on Cancer, Lyon, France.     

Cytogenetic analysis of human oocytes parthenogenetically activated by puromycin

Purpose

Treatment of aged human oocytes by puromycin allows a high rate of parthenogenetic activation and development until the first cleavage division. This technique was used for the study of the chromosome complement of oocytes which remained unfertilized after in vitro fertilization. Three hundred four unfertilized oocytes were treated with 10 Μg/ml puromycin for 6–8 hr and further cultured for 12–15 hr.

Results

Activation occurred in 90.5% of the oocytes. Heterozygous diploids with two pronuclei predominated (61%), which is in contrast to the mouse, where the majority of oocytes activated by puromycin are uniform haploids (89%).

Conclusions

Therefore we conclude that puromycin treatment induces retention of the second polar body in human oocytes, unlike in mouse oocytes treated in the same way. Chromosome analysis performed on 182 oocytes suggested a nondisjunction (ND) rate for the second meiotic division of 12.7%. This is a low figure considering the fact that puromycin itself has been reported to induce nondisjunction. For the first meiotic division a ND rate of only 5.6% was found. This rate is lower than the one found in metaphase II arrested oocytes and we believe that this difference is due to the technical differences between the study of meiotic and that of mitotic chromosomes.