Cellular changes in the prostatic stroma of glucocorticoid-treated rats

Glucocorticoid hormones (GCs) have been widely used for the treatment of prostate cancer because of their inhibitory property against tumour growth. However, their mechanism of action in the prostate has received little attention. Excess GCs can lead to peripheral insulin resistance resulting in hyperglycaemia and hyperinsulinaemia. Insulin plays an important role as a cellular stimulant and high levels are related to low levels of androgens. Our objective has been to describe the effects of insulin resistance induced by dexamethasone treatment on the morphology of rat ventral prostate. Male adult Wistar rats received daily intraperitoneal injections of dexamethasone or saline for five consecutive days after which the rats were killed and the ventral prostate was removed, weighed and prepared for conventional and transmission electron microscopy (TEM). Dexamethasone treatment resulted in atrophy and decreased proliferative activity of prostatic epithelial cells. TEM analysis revealed changes in the epithelium-stroma interface, with some interruptions in the basement membrane. Fibroblasts showed a secretory phenotype with dilated endoplasmic reticulum. Smooth muscle cells exhibited a contractile pattern with 50% atrophy, an irregular membrane and twisted nuclei. Mitochondrial alterations, such as enlarged size and high electron density in the mitochondrial matrix, were also detected in smooth muscle cells. Insulin resistance induced by dexamethasone is thus associated with epithelial atrophy similar to that described for diabetic rats. However, GCs are responsible for morphological changes in the stromal cell population suggesting the activation of fibroblasts and atrophy of the smooth muscle cells.     

Origin and function of tumor stroma fibroblasts

Tumor development is critically dependent on the formation of a supporting stroma consisting of neovasculature, inflammatory cells and activated fibroblasts. Activated fibroblasts present a heterogeneous cell population not only in regard to the expression of marker molecules but also to their origin and molecular signaling properties. The plasticity of this cell type is pointed out by the multiple transdifferentiation events that lead to the generation of activated fibroblasts which can arise from resting fibroblasts, epithelial and endothelial cells as well as from mesenchymal stem cells. Cellular in vitro and in vivo experiments have changed the perspective of fibroblasts from passive “bystanders” in the tumor microenvironment to that of important drivers of tumor progression. Here, we describe the multiple origins of fibroblast recruitment to the tumor tissue as well as the function of activated fibroblasts during tumor initiation, progression, metastasis and anti-VEGF resistance. The identification of markers present in activated fibroblasts as well as a better understanding how these cells influence other tumor compartments has led to the clinical development of anti-tumor therapies.     

Cellular renewal in the parenchyma and stroma of the parathyroid glands

By means of autoradiographic, morphometric and cytophotometric methods main parameters, characterizing processes of cellular renewal have been studied in the parathyroid glands of 66 mature white male rats with body mass of 160-230 g. The time of renewal of the parathyrocyte population is 80-100 days, the average daily mitotic index--0.88 +/- 0.09% 0, the average duration of mitosis--1.61 h, the average daily index of dying cells--0.24 +/- 0.03% 0. The greatest mitotic activity of parathyrocytes is revealed in the evening and early in the morning. At night together with decreasing amount of dividing cells, content of dying parathrocytes increases. The glandular cell population is mainly diploid, polyploid cells make no more than 0.1%. The time of renewal of stromal cells makes 82 +/- 9 days. The results obtained demonstrate that the parathyroid cells should be considered as a slowly renewal population.     

Carotenoid composition of spinach chloroplast grana and stroma lamellae

Stroma lamellae and grana stacks prepared by French press rupture of spinach (Spinacia oleracea) chloroplasts contain similar amounts of β-carotene on a protein basis. The grana fraction has considerably more xanthophylls than does the stroma fraction. Total carotenoid to chlorophyll ratios are similar for both fractions.     

Maternal renal insufficiency alters plasma composition and renal function in the fetal sheep

To determine the effects of chronic maternal renal insufficiency on fetal renal function, we studied nine fetuses whose mothers underwent subtotal nephrectomy at least 2 mo before mating (STNxF) and seven fetuses from intact ewes (IntF) (126-128 days of gestation, term 150 days). STNxF had lower hematocrit (P < 0.05), plasma chloride (P < 0.01), and creatinine levels (P < 0.01), and the length-to-width ratio of their kidneys was reduced (P < 0.05). They excreted twice as much urine (P < 0.05) and sodium (P < 0.01). Total (P = 0.01) and proximal fractional sodium reabsorptions (P < 0.05) were lower in STNxF; distal delivery of sodium (P < 0.05) and distal fractional sodium reabsorption (P < 0.05) were higher. They tended to have suppressed renin levels (P = 0.06). Infusions of amino acids (alanine, glycine, proline, and serine at 0.32 mmol/min for 1 h and 0.64 mmol/min for 2 h intravenously), known to stimulate renal blood flow and glomerular filtration rate in fetal sheep, did so in IntF (P < 0.01). Arterial pressure also increased (P < 0.01). These effects were not observed in STNxF. In summary, chronic maternal renal insufficiency was associated with profound alterations in fetal renal excretion of fluid and electrolytes and impaired renal hemodynamic and glomerular responses to amino acid infusion. Whether these marked changes in the renal function of fetuses carried by STNx ewes are associated with alterations in renal function in postnatal or adult life remains to be determined.     

Cellular and developmental properties of fetal hematopoietic stem cells

We have characterized the fetal totipotent hematopoietic stem cell using a novel strategy that integrates physical analysis of cell properties and genetic analysis of in vivo developmental behavior. This approach allows the simultaneous isolation and in vivo characterization of any stem cell population. Using this procedure we demonstrate that a cell surface marker, recognized by monoclonal antibody AA4.1, defines 0.5%-1.0% of fetal liver tissue that contains the entire hierarchy of primitive hematopoietic cells. The AA4.1+ subpopulation includes multipotential in vitro progenitors, CFU-S cells, and lymphoid-myeloid stem cells that function to yield permanent and oligoclonal blood systems. Further fractionation of these cells by analysis of density, fibronectin binding, and surface antigen distribution has defined 0.1%-0.2% of fetal liver that contains the totipotent stem cell.     

Cellular fatty acid composition ofCorallococcus coralloides

The fatty acid composition of five strains ofCorallococcus coralloides and three reference species ofMyxococcus were determined by gas-liquid chromatography. Methyl esters of fatty acid containing from 12 to 22 carbon atoms were identified. The major fatty acids present were C₁₅ and C₁₇ saturated branched chain, and both C₁₆ saturated and unsaturated straight chain acids. The C₁₇ saturated branched and straight chain acids, which were in valuable concentration in species ofMyxococcus, were not, however, detected in all strains ofC. coralloides. The application of these results in the distinction ofC. coralloides from the genusMyxococcus is discussed.     

Cellular fatty acid composition of Leuconostoc oenos

The cellular fatty acid composition of 70 lactic acid bacteria was examined by capillary gas chromatography. Fifty-four Leuconostoc oenos strains, including three reference, type strains from the other Leuconostoc spp., nine Pediococcus spp. and two Lactobacillus spp. were studied. Eighteen fatty acids were determined, of which 10 were identified by gas chromatography-mass spectrometry. The relative percentages of the 18 fatty acids of the Leuconostoc strains were analyzed numerically and grouped using the unweighted pair-group method. Results show that four clusters could be defined at r = 0.920, with five strains unassigned. The major fatty acids of the Leuc. oenos strains were found to be palmitic acid (C16:0), palmitoleic acid (C16:1–9), oleic acid (C18: 1–9), vaccenic acid (C18: 1–11), dihyrosterculic acid (C19-cyclopropane-9) and lactobacillic acid (C19-cyclopropane-11). It was mainly on the basis of the amounts of oleic acid and the C19-cyclopropane fatty acids that the strains of Leuc. oenos could be distinguished from each other. This is the first report of the occurrence of dihydrosterculic acid in lactic acid bacteria. For the majority of Leuc. oenos strains, the result obtained with the cellular fatty acid analysis confirmed the phenotypic relationships.     

Cellular function and molecular structure of ecto-nucleotidases

Ecto-nucleotidases play a pivotal role in purinergic signal transmission. They hydrolyze extracellular nucleotides and thus can control their availability at purinergic P2 receptors. They generate extracellular nucleosides for cellular reuptake and salvage via nucleoside transporters of the plasma membrane. The extracellular adenosine formed acts as an agonist of purinergic P1 receptors. They also can produce and hydrolyze extracellular inorganic pyrophosphate that is of major relevance in the control of bone mineralization. This review discusses and compares four major groups of ecto-nucleotidases: the ecto-nucleoside triphosphate diphosphohydrolases, ecto-5'-nucleotidase, ecto-nucleotide pyrophosphatase/phosphodiesterases, and alkaline phosphatases. Only recently and based on crystal structures, detailed information regarding the spatial structures and catalytic mechanisms has become available for members of these four ecto-nucleotidase families. This permits detailed predictions of their catalytic mechanisms and a comparison between the individual enzyme groups. The review focuses on the principal biochemical, cell biological, catalytic, and structural properties of the enzymes and provides brief reference to tissue distribution, and physiological and pathophysiological functions.     

The function of adipocytes in the bone marrow stroma

The fibroblasts and adipocytes of the bone marrow stroma provide the cytokines and extracellular matrix proteins required for the maturation and proliferation of the circulating blood cells. Due to the complexity of the bone marrow as an organ, the normal physiology of these stromal cells is not well understood. In particular, the role of adipocytes in the bone marrow remains controversial. Cloned bone marrow stromal cell lines provide an in vitro model for analysis of the lympho-hematopoietic microenvironment. These cells may be capable of multiple differentiation pathways, assuming the phenotype of adipocytes, chondrocytes, myocytes, and osteocytes in vitro. Characterization of these cell lines and recent in vivo experiments give new insight into the normal physiology of the bone marrow.     

Obstructive jaundice expands intrahepatic regulatory T cells, which impair liver T lymphocyte function but modulate liver cholestasis and fibrosis

Although obstructive jaundice has been associated with a predisposition toward infections, the effects of bile duct ligation (BDL) on bulk intrahepatic T cells have not been clearly defined. The aim of this study was to determine the consequences of BDL on liver T cell phenotype and function. After BDL in mice, we found that bulk liver T cells were less responsive to allogeneic or syngeneic Ag-loaded dendritic cells. Spleen T cell function was not affected, and the viability of liver T cells was preserved. BDL expanded the number of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg), which were anergic to direct CD3 stimulation and mediated T cell suppression in vitro. Adoptively transferred CD4(+)CD25(-) T cells were converted into Treg within the liver after BDL. In vivo depletion of Treg after BDL restored bulk liver T cell function but exacerbated the degrees of inflammatory cytokine production, cholestasis, and hepatic fibrosis. Thus, BDL expands liver Treg, which reduce the function of bulk intrahepatic T cells yet limit liver injury.     

Troponin: regulatory function and disorders

Study of the molecular biology of the calcium regulation of muscle contraction was initiated by Professor Ebashi’s discovery of a protein factor that sensitized actomyosin to calcium ions. This protein factor was separated into two proteins: tropomyosin and a novel protein named troponin. Troponin is a Ca²⁺-receptive protein for the Ca²⁺-regulation of muscle contraction and, in association with tropomyosin, sensitizes actomyosin to Ca²⁺. Troponin forms an ordered regulatory complex with tropomyosin in the thin filament. Several regulatory properties of troponin, which is composed of three different components, troponins C, I, and T, are discussed in this article. Genetic studies have revealed that many mutations of genes for troponin components, especially troponins T and I, are involved in the three types of inherited cardiomyopathy. Results of functional analyses indicate that changes in the Ca²⁺-sensitivity caused by troponin mutations are the critical functional consequences leading to these disorders. Recent results of this pathophysiological aspect of troponin are also discussed.     

Analysis of the polypeptide composition of grana and stroma thylakoids by two-dimensional gel electrophoresis. Distribution of photosystem II between grana and stroma lamellae

The polypeptide composition of whole thylakoids and membrane subfragments was studied by using a modified two-dimensional gel electrophoresis technique of O'Farrell [J. Biol. Chem. 250, 4007-4021 (1975)]. The modifications were lithium dodecyl sulphate solubilization instead instead of SDS, reverse isofocusing and sensitive silver staining procedure. This high-resolution technique allowed us to separate and identify about 170 polypeptides of thylakoid membranes. After separating grana and stroma thylakoids it was found that both types of lamellae contained nearly equal amounts of polypeptides, but about 70 polypeptides were different in the two preparations. In grana thylakoids, 54 polypeptides out of 95 were found to be mainly present in grana and 31 of them were only present in grana preparations. In stroma membranes, 43 polypeptides out of 99 were mainly present in stroma lamellae and 38 of these polypeptides were exclusively present in stroma lamellae. In a functional photosystem II preparation, 61 individual polypeptides could be distinguished. Most of these polypeptides were present in both grana and stroma lamellae, but 22 of them were more pronounced in grana than in stroma lamellae. 9 polypeptides of photosystem II were distinctly different in grana and stroma lamellae, and these differences may connect closely with the functional differences of photosystem II in the two types of thylakoids.