Cortico-muscular coupling in a patient with postural myoclonus

We investigated the cortico-muscular coherence in a patient with posturally induced cortically originating negative myoclonus. We recorded simultaneously 50 channels EEG and EMG from quadriceps and biceps femoris muscles of the left upper leg. Three experimental conditions were investigated with the patient in a seated position: (i) recording during rest (Rest), (ii) recording while the patient had to hold his left leg horizontally stretched out (Postural), and (iii) recording while the patient had to hold his left leg horizontally stretched out against a vertical force (Postural against force). Coherence, phase difference and cumulant density were computed as indicators for cortico-muscular coupling. The cortical component preceding the silent period was shown by averaging and was reconstructed. During postural and postural against force conditions, the EEG over the vertex was significantly coherent with EMG, in alpha (7-15 Hz) and beta range (15-30 Hz). The strongest coherence peak was at 21 Hz. No high-frequency coherence was observed. The phase difference and the cumulant density estimate corresponded to a 32 ms time lag between motor cortex and muscles, with EEG leading. The broadening of the coherence spectrum at which the motor cortex drives the muscles together with the excessive coherence levels and the giant SEP could reflect the hyperexcitability of the sensorimotor cortex. The frequency content of the coherence may be characteristic for this type of myoclonus. The results lend support to the view that the frequency analysis may have some diagnostic potential in cortical myoclonus.     

Murine yolk sac endoderm- and mesoderm-derived cell lines support in vitro growth and differentiation of hematopoietic cells

The mechanisms involved in the induction of yolk sac mesoderm into blood islands and the role of visceral endoderm and mesoderm cells in regulating the restricted differentiation and proliferation of hematopoietic cells in the yolk sac remain largely unexplored. To better define the role of murine yolk sac microenvironment cells in supporting hematopoiesis, we established cell lines from day-9.5 gestation murine yolk sac visceral endoderm and mesoderm layers using a recombinant retrovirus vector containing Simian virus 40 large T- antigen cDNA. Obtained immortalized cell lines expressed morphologic and biosynthetic features characteristic of endoderm and mesoderm cells from freshly isolated yolk sacs. Similar to the differentiation of blood island hematopoietic cells in situ, differentiation of hematopoietic progenitor cells in vitro into neutrophils was restricted and macrophage production increased when bone marrow (BM) progenitor cells were cultured in direct contact with immortalized yolk sac cell lines as compared with culture on adult BM stromal cell lines. Yolk sac- derived cell lines also significantly stimulated the proliferation of hematopoietic progenitor cells compared with the adult BM stromal cell lines. Thus, yolk sac endoderm- and mesoderm-derived cells, expressing many features of normal yolk sac cells, alter the growth and differentiation of hematopoietic progenitor cells. These cells will prove useful in examining the cellular interactions between yolk sac endoderm and mesoderm involved in early hematopoietic stem cell proliferation and differentiation.     

Two populations of self-maintaining monocyte-independent macrophages exist in adult epididymis and testis

Macrophages are the principal immune cells of the epididymis and testis, but their origins, heterogeneity, development, and maintenance are not well understood. Here, we describe distinct populations of epididymal and testicular macrophages that display an organ-specific cellular identity. Combining in vivo fate-mapping, chimeric and parabiotic mouse models with in-depth cellular analyses, we found that CD64^hiMHCII^lo and CD64^loMHCII^hi macrophage populations of epididymis and testis arise sequentially from yolk sac erythro-myeloid progenitors, embryonic hematopoiesis, and nascent neonatal monocytes. While monocytes were the major developmental source of both epididymal and testicular macrophages, both populations self-maintain in the steady-state independent of bone marrow hematopoietic precursors. However, after radiation-induced macrophage ablation or during infection, bone marrow-derived circulating monocytes are recruited to the epididymis and testis, giving rise to inflammatory macrophages that promote tissue damage. These results define the layered ontogeny, maintenance and inflammatory response of macrophage populations in the male reproductive organs.

Macrophages are important effector cells of the innate immune system and play a critical role in host defense. They also contribute to tissue homeostasis, aid tissue repair, and promote the resolution of inflammation. In order to perform these diverse roles, macrophages are composed of different populations with distinct origins, which can change their phenotype and functions in response to the tissue microenvironment or upon encountering inflammatory cues (1, 2).Tissue-resident macrophages arise from three distinct waves of embryonic hematopoiesis and maintain themselves by local self-renewal (3, 4). In mice, the first wave of embryonic hematopoiesis, termed “primitive hematopoiesis,” gives rise to primitive yolk sac (YS) macrophages (5). A second wave of YS hematopoiesis follows, which generates late erythro-myeloid progenitors (EMPs) that then migrate and colonize the fetal liver (FL). There they continue to generate myeloid progenitors, including FL monocytes (MOs), which contribute to most tissue macrophage populations, except microglia (6, 7). The third wave of hematopoiesis starts in the para-aortic splanchnopleural/aorta-gonad-mesonephros region, giving rise to immature hematopoietic stem cells (HSCs), which then migrate, colonize, and differentiate in the FL to establish definitive hematopoiesis (8, 9). Immediately before birth, hematopoiesis switches from the FL to the bone marrow (BM), and after 1 wk of age BM monocytes (BM-MOs) are generated and circulate in the blood, ready for recruitment into tissues in response to inflammatory cues (9). In some organs, such as the intestine, pancreas, and dermis, BM-MOs can contribute to the pool of tissue macrophages in the steady state/under inflammation and replace those derived during embryonic development (10–13), however it is not known whether this occurs in all organs or is restricted to specific situations.Among the male reproductive organs, the epididymis and testis are unique immunological sites where macrophages represent the most prevalent immune cell population (14–16). Recent studies indicate that testicular macrophages have a phenotype and functional profile consistent with a role in maintaining immune tolerance/privilege in the testis (17, 18), but very little is known of the phenotype or function of epididymal macrophages. What we do know is that infection, inflammation, and autoimmunity in the male reproductive tract are common health issues, and also underlie around 15% of all cases of male infertility (19). So far, the possible role of macrophages in these conditions has received little attention. A recent report identified two macrophage populations in adult mouse testes: Interstitial macrophages (CD64^hiMHCII^lo) and peritubular macrophages (CD64^loMHCII^hi) (16). The CD64^hiMHCII^lo population was found to originate from embryonic progenitors, whereas CD64^loMHCII^hi cells appeared only postnatally in the testis and were thought to arise from BM-derived cells (16). However, the relative contributions of the embryonic progenitors to the adult testes-resident macrophages, and how testicular macrophages maintain themselves in adulthood are not yet defined. Furthermore, the origin and maintenance of epididymal macrophages in adulthood is completely lacking.Here, we define the cellular identity, development, and maintenance of macrophage populations that reside in adult mouse testis and epididymis. Using immunophenotyping, fate-mapping analyses, long-term parabiosis, and BM transplantation, we observed that steady-state epididymis and testis contain two self-maintaining adult MO-independent macrophage populations: CD64^hiMHCII^lo and CD64^loMHCII^hi, both arising either embryonically from fetal MOs or immediately after birth from neonatal nascent blood MOs. However, when the macrophage niche was emptied by irradiation, engrafted BM-MOs differentiated into tissue-resident macrophages in both organs. During bacterial infection, the recruitment of BM-MOs was also associated with tissue damage. We provide an alternative view to the current paradigm that testicular CD64^loMHCII^hi macrophages arise from blood monocytes in the steady state, showing instead that fetal/neonatal monocytes give rise to these populations which then self maintain during adulthood.