Telocytes and putative stem cells in ageing human heart

Tradition considers that mammalian heart consists of about 70% non‐myocytes (interstitial cells) and 30% cardiomyocytes (CMs). Anyway, the presence of telocytes (TCs) has been overlooked, since they were described in 2010 (visit www.telocytes.com ). Also, the number of cardiac stem cells (CSCs) has not accurately estimated in humans during ageing. We used electron microscopy to identify and estimate the number of cells in human atrial myocardium (appendages). Three age‐related groups were studied: newborns (17 days–1 year), children (6–17 years) and adults (34–60 years). Morphometry was performed on low‐magnification electron microscope images using computer‐assisted technology. We found that interstitial area gradually increases with age from 31.3 ± 4.9% in newborns to 41 ± 5.2% in adults. Also, the number of blood capillaries (per mm²) increased with several hundreds in children and adults versus newborns. CMs are the most numerous cells, representing 76% in newborns, 88% in children and 86% in adults. Images of CMs mitoses were seen in the 17‐day newborns. Interestingly, no lipofuscin granules were found in CMs of human newborns and children. The percentage of cells that occupy interstitium were (depending on age): endothelial cells 52–62%; vascular smooth muscle cells and pericytes 22–28%, Schwann cells with nerve endings 6–7%, fibroblasts 3–10%, macrophages 1–8%, TCs about 1% and stem cells less than 1%. We cannot confirm the popular belief that cardiac fibroblasts are the most prevalent cell type in the heart and account for about 20% of myocardial volume. Numerically, TCs represent a small fraction of human cardiac interstitial cells, but because of their extensive telopodes, they achieve a 3D network that, for instance, supports CSCs. The myocardial (very) low capability to regenerate may be explained by the number of CSCs, which decreases fivefold by age (from 0.5% to 0.1% in newborns versus adults).     

Integration sites of human papillomavirus 18 DNA sequences on HeLa cell chromosomes

Human papillomaviruses (HPV) 16 and 18 are closely linked with human genital cancer. In most cervical carcinomas, viral sequences are integrated into the host genome. HeLa, a cervical carcinoma cell line, has multiple copies of integrated HPV 18 DNA. In this study, in situ chromosome hybridization was used to assign the integration sites of HPV 18 DNA sequences on HeLa cell chromosomes. Four sites of hybridization were identified at 8q23----q24, 9q31----q34, p11----p13 on an abnormal chromosome 5, and q12----q13 on an abnormal 22. Three of these sites correspond with the locations of MYC, ABL, and SIS protooncogenes, and are at or in close proximity to fragile sites. The chromosomal localization of HPV 18 DNA may be useful in assessing the role of viral integration in the development of this malignancy.     

Two novel reciprocal translocations involving chromosome 6 in the domestic pig]

In the present study 2 new reciprocal translocations are described in two hypoprolific boars. The first one, a Gascon/Meishan boar, has produced a mean value of 7.37 +/- 0.69 piglets, vs 12.41 +/- 0.22 piglets per litter in contemporaries. The second one, a Pietrain/Large-White boar, has produced a mean of 5.42 +/- 0.69 vs 12.41 +/- 0.22 piglets per litter in contemporaries. Each of these animals carries a new chromosome translocation involving chromosomes 6, 8 and 15, respectively. The first translocation seems to be a de novo occurring abnormality. The economic consequences of these abnormalities are discussed. Carrier of the gene HAL, the abnormal chromosomes 6 involved in these translocations are important, and could useful markers in gene mapping and flow cytometry studies in pigs.     

Topological regulation of cell-membrane phosphoinositidase C.

Although the translocation of protein kinase C and phospholipase A2 are well documented, no information is available about the possible down-modulation of transmembrane phospholipase C. We found that TPA induced a dose-dependent (10-200 nM) and time-dependent (15 min-6 h) down-modulation of transmembrane phosphoinositidase C (PLC-PI) on lymphoid cells (CEM-CM3 and WIL2-NS) and epitheloid carcinoma cells (HeLa S3) but not on human fibroblasts (MRC-5). Cell-surface expression of PLC-PI on intact cells was assayed by flow cytometry using saturating concentrations of polyclonal anti-PLC-PI antibodies and phycoerythrin-conjugate. A control phorbol-ester which does not activate protein kinase C (PKC) had no internalization effect on PLC-PI. PKC inhibitors staurosporine (2.5 nM) and H-7 (10 microM) partially inhibited the TPA effect. Cytochalasin B (40 micrograms/ml) did not modify the TPA-induced PLC-PI down-modulation. The effect of TPA on PLC-PI seems quite specific since no internalization was induced by TPA on transmembrane phosphatidylcholine-preferring PLC expression. These results show that TPA can translocate the membrane-bound PLC-PI, probably by PKC activation.     

The Gram Stain after More than a Century

The Gram stain, the most important stain in microbiology, was described more than a century ago. Only within the past decade, however, has an understanding of its mechanism emerged. It now seems clear that the cell wall of Gram-positive microorganisms is responsible for retention of a crystal violet:iodine complex. In Gram-negative cells, the staining procedures damage the cell surface resulting in loss of dye complexes. Gram-positive microorganisms require a relatively thick cell wall, irrespective of composition, to retain the dye. Therefore, Gramstainability is a function of the cell wall and is not related to chemistry of cell constituents. This review provides a chronology of the Gram stain and discusses its recently discovered mechanism.     

A histochemical method for L-amino acid tetrazolium reductase

Summary Some incubation media were elaborated to demonstrate tissue activity of L-amino acid tetrazolium reductase. These media had as substrate a L-amino acid to which a small amount of L-glutamate was added, well below the concentration used to demonstrate glutamic-dehydrogenase.The specifity of the reactions was assessed by incubations in control media and by studying the effects of some inhibitors. The work was concerned both with the actual pattern of the reaction and with changes initiated in the medium by tissue incubation.It became obvious that in this way an actual visualisation of an enzymatic oxido-reductive activity of various degrees in tissues and organs was possible.