The bone marrow constitutes a reservoir of pericyte progenitors

Adult bone marrow is a rich reservoir of hematopoietic and mesenchymal stem and progenitor cells. Mobilization and recruitment of bone marrow-derived cells to injured or ischemic tissue or tumors endorse the initiation and maintenance of angiogenic processes in the adult by incorporating endothelial progenitor cells (EPC) into the developing vasculature and by recruiting accessory hematopoietic cells. Recent data have now revealed that the origin of bone marrow-derived vascular cells is not restricted to endothelial cells but also includes pericytes--the perivascular support cells. Several laboratories have now reported the existence of pericyte progenitor cells, and these cells, like EPC, can be mobilized and recruited to the remodeling vasculature under ischemic conditions and in tumors. This review focuses on pericytes in vessel formation and on recent discoveries about their bone marrow origin in the adult.     

Magnetic resonance imaging of injected silicone: findings in seven male-to-female transsexuals

Our goal was to describe the MR findings of subcutaneously injected silicone in male-to-female transsexuals and to determine the most optimal combination of pulse sequences for discrimination of injected silicone from the surrounding structures. Seven male-to-female transsexuals were referred for MRI in order to detect the injected silicone in the subcutaneous tissues and to visualize distant migration and possible complications. Conventional spin-echo (SE) T1-weighted and turbo SE proton-density/T2-weighted, plain short tau inversion recovery (STIR), and two STIR sequences with, respectively, water and silicone suppression were applied at 1.5 T. Three observers trained in MRI analysed the images separately for the abnormalities and rated the images using a four-level scale. The STIR with water suppression provided the highest contrast between silicone and the surrounding adipose tissue. Silicone-specific STIR pulse sequences provided clear images for the evaluation of the amount and patterns of local and distant spread of injected fluid silicone. Magnetic resonance imaging readily identifies the subcutaneously injected silicone, its distant migration and the amount of tissue disorganization around the silicone deposits. Two silicone-specific STIR sequences are usually sufficient for imaging the spread of silicone.     

The PTEN/Akt pathway dictates the direct alphaVbeta3-dependent growth-inhibitory action of an active fragment of tumstatin in glioma cells in vitro and in vivo

The collagen type IV cleavage fragment tumstatin and its active subfragments bind to integrin alpha(V)beta(3) and inhibit activation of focal adhesion kinase, phophoinositol-3 kinase, Akt, and mammalian target of rapamycin (mTOR) in what is thought to be an endothelial cell-specific manner. The resultant endothelial cell apoptosis accounts for the ability of tumstatin to function as an endogenous inhibitor of angiogenesis and an indirect suppressor of tumor growth. We hypothesized that the inability of tumstatin to directly suppress tumor cell growth might be the result of the constitutive activation of the Akt/mTOR pathway commonly seen in tumors. Consistent with this idea, several integrin alpha(V)beta(3)-expressing glioma cell lines with PTEN mutations and high levels of phospho-Akt (pAkt) were unaffected by exposure to an active fragment of tumstatin (T3), whereas alpha(V)beta(3)-expressing glioma cell lines with a functional PTEN/low levels of pAkt exhibited T3-induced growth suppression that could be bypassed by small interfering RNA-mediated suppression of PTEN, introduction of a constitutively expressed Akt, or introduction of the Akt and mTOR target eukaryotic translation initiation factor 4E. The direct tumor-suppressive actions of T3 were further shown in an alpha(V)beta(3)-deficient in vivo mouse model in which T3, while unable to alter the tumstatin-insensitive vasculature contributed by the alpha(V)beta(3)-deficient host, nonetheless suppressed the growth and proliferative index of i.c. implanted alpha(V)beta(3)-expressing PTEN-proficient glioma cells. These results show that tumstatin, previously considered to be only an endogenous inhibitor of angiogenesis, also directly inhibits the growth of tumors in a manner dependent on Akt/mTOR activation.     

Evaluation of the extent of nursing involvement required with home pentamidine isethionate infusions

A retrospective review of 20 patients was undertaken to evaluate the extent of nursing involvement required in patients receiving daily Pentamidine infusions. The population was divided into two groups: a) nurse-administered infusions, and b) self-administered infusions. Both groups were evaluated for: 1. Incidence and severity of side effects; 2. Prophylactic measures; 3. Length of infusion and/or nursing visit. A protocol was developed for self-administration of Pentamidine and criteria established for patients to qualify for this independent responsibility. With established protocols and comprehensive patient education, select individuals can safely administer Pentamidine at home with less nursing involvement than previously recognized.