Role in host cell invasion of Trypanosoma cruzi-induced cytosolic-free Ca2+ transients.

Trypanosoma cruzi enters cells by a unique mechanism, distinct from phagocytosis. Invasion is facilitated by disruption of host cell actin microfilaments, and involves recruitment and fusion of host lysosomes at the site of parasite entry. These findings implied the existence of transmembrane signaling mechanisms triggered by the parasites in the host cells before invasion.

Localization of the type 3 inositol 1,4,5-trisphosphate receptor in the Ca2+ wave trigger zone of pancreatic acinar cells.

Agonist-induced cytosolic Ca2+ (Ca2+i) signals begin as apical-to-basal Ca2+i waves in pancreatic acinar cells and in other polarized epithelia. However, the basis of this polarized Ca2+i signaling pattern is unknown. Here we use immunocytochemistry to demonstrate that the type 3 inositol trisphosphate receptor is localized to the extreme apex of pancreatic acinar cells, the region which corresponds to the trigger zone from which Ca2+i signals originate in this cell type (Kasai, H.

In vitro proteoglycan synthesis in response to extracts of demineralized bone.

Two extracts of bovine bone, bone morphogenetic protein (BMP) supplied by the UCLA Bone Research Laboratory, and osteogenic factor extract (OFE) supplied by the industrial group Celtrix Pharmaceuticals, were tested for the ability to transform embryonic skeletal muscle into cartilage. Skeletal muscle was placed into organ cultures on substrata of Type I collagen and fed with concentrations of the extracts that their originators reported to be effective; however, only BMP was capable of eliciting the morphologic differentiation of cartilage. In contrast, both extracts supported patterns of glycosaminoglycan synthesis that mimicked the biochemical differentiation of cartilage-type extracellular matrix.

Tauroursodeoxycholic acid stimulates hepatocellular exocytosis and mobilizes extracellular Ca++ mechanisms defective in cholestasis.

To assess the effects of tauroursodeoxycholic acid (TUDCA) on bile excretory function, we examined whether TUDCA modulates vesicular exocytosis in the isolated perfused liver of normal rats in the presence of high (1.9 mM) or low (0.19 mM) extracellular Ca++ and in cholestatic rats 24 h after bile duct ligation.

Endothelin-1 induces cholestasis which is mediated by an increase in portal pressure.

Endothelin-1 (ET-1) is a potent vasoactive peptide which generally exerts its effect on target cells by increasing [Ca++]i. Both vasoconstriction (resulting in an increase in perfusion pressure) and increased [Ca++]i are actions of ET-1 that may result in cholestasis. Single-pass isolated perfused rat liver (IPRL) were used, and [Ca++]i was measured in both populations of hepatocytes and single cells.

Effects of tauroursodeoxycholic acid on cytosolic Ca2+ signals in isolated rat hepatocytes.

Background: Tauroursodeoxycholic acid (TUDCA) is of potential benefit in cholestatic disorders. However, the effects of TUDCA on cytosolic free calcium [(Ca2+)i], which regulates hepatocyte secretion, are unknown.

Methods: The effect of TUDCA on (Ca2+)i was investigated in groups of isolated rat hepatocytes by microspectrofluorometry and in single cells by confocal line scanning microscopy.

The fate of Borrelia burgdorferi, the agent for Lyme disease, in mouse macrophages. Destruction, survival, recovery.

The macrophage is a known reservoir for a number of infectious agents, and is therefore a likely candidate site for persistence of Borrelia burgdorferi, the Lyme spirochete. We report that unopsonized B. burgdorferi enter macrophages rapidly, resulting mainly in degradation but occasionally in apparent intracellular persistence.

Immunocytochemical expression and localization of protein kinase C in bovine aortic endothelial cells.

Total PKC activity in BAEC incubated for 24 hrs in either 10% serum (FBS) or serum-deprived media (SDM) was similar. However, most of the activity (69%) in the FBS group was detected in the particulate fraction, while it was mainly in the cytosolic fraction (66%) in the SDM group. By confocal microscopy, there was diffuse cytoplasmic localization of the antibodies to the alpha and beta PKC isoforms.

Mechanisms of subcellular cytosolic Ca2+ signaling evoked by stimulation of the vasopressin V1a receptor.

Receptor activation may result in distinct subcellular patterns of Ca2+ release. To define the subcellular distribution of Ca2+i signals induced by stimulation of the vasopressin V1a receptor, we expressed the cloned receptor in Xenopus oocytes. Oocytes were then loaded with fluo-3 and observed using confocal microscopy.

Mechanism of Ca2+ wave propagation in pancreatic acinar cells.

An increase in cytosolic Ca2+ often begins as a Ca2+ wave, and this wave is thought to result from sequential activation of Ca(2+)-sensitive Ca2+ stores across the cell. We tested that hypothesis in pancreatic acinar cells, and since Ca2+ waves may regulate acinar Cl- secretion, we examined whether such waves also are important for amylase secretion. Ca2+ wave speed and direction was determined in individual cells within rat pancreatic acini using confocal line scanning microscopy.

Miliary tuberculosis with acute respiratory failure and histiocytic hemophagocytosis. Successful treatment with extracorporeal lung support and epipodophyllotoxin VP 16-213.

A 14-year-old girl with high fever, dyspnea and bilateral miliary nodules on chest X-ray, developed a rapidly progressive respiratory failure associated with histiocytic hemophagocytosis. Histologic examination of bone marrow biopsy revealed tuberculous granulomas with caseating necrosis. We report a pediatric case in which treatment with extracorporeal lung support and epipodophyllotoxin VP 16-213 was successful.

Differential effects of the 3',5'-cyclic adenosine monophosphate and protein kinase C pathways on the response of isolated rat osteoclasts to calcitonin.

Calcitonin (CT) activates both the cAMP and the protein kinase C (PKC) pathways in the kidney cell line LLC-PK1. Although CT also activates cAMP in osteoclasts, its effects on PKC in this cell type are unknown. In order to determine whether the response of osteoclasts to CT also involves the PKC pathway, the effects of activators and inhibitors of PKC on bone resorption and cell surface area were analyzed in isolated rat osteoclasts.

Hormonal regulation of paracellular permeability in isolated rat hepatocyte couplets.

Many hormones and drugs exert their effects on cells by increasing cytosolic Ca2+ (Cai2+) and activating protein kinase C (PKC). Each of these actions results in cholestasis in the isolated perfused rat liver, but the responsible mechanisms are unclear. We used isolated rat hepatocyte couplets to observe the direct effects of increased Cai2+ and PKC activation on permeability of the hepatocyte tight junction and canalicular volume, two possible determinants of hepatocyte bile secretion.

[Acute heart insufficiency in an 8-month-old infant presenting with hypocalcemia and Epstein-Barr virus infection: acute myocarditis? Or primary hypokinetic dilated cardiomyopathy?].

An eight-month-old was admitted for acute congestive heart failure with fever. The respective parts played by hypocalcemia (due to vitamin-D deficiency rickets) and acute Epstein-Barr virus infection are discussed. Hypocalcemia was sufficiently marked to induce heart failure per se but replenishment of calcium stores was followed by only partial improvement in cardiac manifestations.

Subcellular distribution of cytosolic Ca2+ in isolated rat hepatocyte couplets: evaluation using confocal microscopy.

Ca2+ agonists induce Ca2+ waves and other non-uniform Ca2+ patterns in the cytosol of epithelial cells. To define subcellular Ca2+ transients in the cytosol of hepatocytes we examined Fluo-3-loaded isolated rat hepatocyte couplets using confocal microscopy. Optical sections of less than 1 micron in thickness were observed in couplets, and fluorescence from cytosolic Ca2+ signals was readily distinguished from nuclear, mitochondrial, and lysosomal fluorescence.

Effects of Ca2+ agonists on cytosolic Ca2+ in isolated hepatocytes and on bile secretion in the isolated perfused rat liver.

The effects of increases in cytosolic Ca2+ on hepatocyte bile secretion are unknown. A number of agents that alter levels of cytosolic Ca2+ in the hepatocyte also produce hepatic vasoconstriction and activate protein kinase C, which complicates interpretations of their effects on bile secretion. To better understand the role of cytosolic Ca2+ in bile secretion, we examined the effect of the Ca2+ ionophore A23187 (0.

Coordination of hormone-induced calcium signals in isolated rat hepatocyte couplets: demonstration with confocal microscopy.

Excitable cells often display rapid coordination of hormone-induced intracellular calcium signals. Calcium elevations that begin in a single epithelial cell also may spread to adjacent cells, but coordination of hormone-induced signals among epithelial cells has not been described. We report the use of confocal microscopy to determine the inter- and intracellular distribution of cytosolic calcium in isolated rat hepatocyte couplets, an isolated epithelial cell system in which functional polarity is maintained.

Juvenile chronic myelocytic leukemia with unusual cytogenetic clonal evolution.

Cytogenetic studies are reported in a case of juvenile chronic myelocytic leukemia with dysmyelopoiesis and skin involvement. The clonal evolution of a 6q-anomaly is described. Hematological and cytogenetic findings suggest a role of hematopoietic stem cell in this patient for whom the outcome was fatal.

The role of SPECT brain imaging in assessing psychopathology in the medically ill.

Cerebral single photon emission computed tomography (SPECT), a method of functional brain imaging, measures cerebral blood flow and metabolism. This paper describes the imaging procedure and several cases where cerebral SPECT was of use in the differential diagnosis of medically ill patients who also presented with psychopathology. SPECT patterns in cerebrovascular disease, dementia, focal epilepsy, and AIDS are at present the best described and seem to be the most specific.

Regulation of intestinal iron absorption and mucosal iron kinetics in hereditary hemochromatosis.

In hereditary hemochromatosis (HH), increased intestinal iron absorption leads to the development of iron overload. To examine the abnormal regulation of iron absorption in this disorder, we analyzed mucosal iron kinetics in six patients with HH and in five normal subjects by using a compartmental model of intestinal iron absorption and systemic ferrokinetics. Subjects were given simultaneous oral and intravenous tracer doses of iron 59-labeled citrate and iron 55-labeled transferrin, respectively.