Isolated right ventricular dysfunction in systemic sclerosis: latent pulmonary hypertension?

Right ventricular function is frequently abnormal in patients with systemic sclerosis, but whether this is related to pulmonary vascular complications of the disease is unclear. Standard echocardiography with tissue Doppler imaging was performed at rest and during exercise for the study of right ventricular function and pulmonary circulation in 25 consecutive systemic sclerosis patients and in 13 age-matched healthy controls. When compared with the controls, the patients had no difference in systolic right ventricular pressure gradient, but a decreased pulmonary flow acceleration time, and increased right ventricular free wall thickness and end-diastolic dimensions. At the tricuspid annulus, the E maximal velocity was decreased (8.9 +/- 4 versus 11.7 +/- 2.3 cm.s(-1)) and the isovolumic relaxation time corrected to RR interval was increased (6.5 +/- 2.9 versus 4.5 +/- 2.5%). The tissue Doppler imaging profile at the mitral annulus was similar in both groups. At exercise, 18 patients had a decreased maximum workload and cardiac output, no change in systolic right ventricular pressure gradient, but an increase in the slope of pulmonary artery pressure/flow relationships. These results suggest that patients with systemic sclerosis may present with latent pulmonary hypertension as a likely cause of right ventricular diastolic dysfunction, as revealed by stress echocardiography and tissue Doppler imaging.     

Radiochemical dates obtained by alpha spectrometry on fossil mollusk shell from the 5e Atlantic shoreline of the High Atlas, Morocco.

The reported radiochemical results obtained on 77 samples collected from Moroccan fossil beaches assumed to be deposited during the above present sea-level high stands corresponding to 5e climatic stage, and on 12 present and Holocene samples, are discussed in order to judge the age validity. Contrary to the Holocene shells where (238)U contents are low and (234)U/(238)U are in agreement with sea-water ratio, the 5e results vary considerably irrespective of species and calcite content of samples. Because of the open-system possibility, the (230)Th/(234)U ages based on shell samples should be interpreted as minima for any studied shoreline discussed in the light of geological data and several shells analyses.     

Regulation of 5-hydroxytryptamine-induced calcium mobilization by cAMP-elevating agents in cultured canine tracheal smooth muscle cells

The effects of increases in cellular adenosine 3′5′-cyclic monophosphate (cAMP) on 5-hydroxytryptamine-(5-HT-) induced generation of inositol phosphates (IPs) and increases in intracellular Ca²⁺ ([Ca²⁺]_i) were investigated using canine cultured tracheal smooth muscle cells (TSMCs). Cholera toxin and forskolin induced concentration- and time-dependent cAMP formation with half-maximal effects (−logEC₅₀) produced at concentrations of 7.0 ± 0.5 and 4.9 ± 0.4  respectively. Pretreatment of TSMCs with either forskolin or dibutyryl cAMP inhibited 5-HT-stimulated responses. Even after treatment for 24h, these agents still inhibited the 5-HT-induced Ca²⁺ mobilization. The inhibitory effects of these agents produced both depression of the maximal response and a shift to the right of the concentration response curves of 5-HT. The water-soluble forskolin analogue L-858051 [7-deacetyl-7β-(γ-N-methylpiperazino)-butyryl forskolin] significantly inhibited the 5-HT-stimulated accumulation of IPs. In contrast, the addition of 1,9-dideoxy forskolin, an inactive forskolin analogue, had little effect on this response. Moreover, SQ-22536 [9-(tetrahydro-2-furanyl)-9-H-purin-6-amine], an inhibitor of adenylate cyclase, and both H-89 [N-(2-aminoethyl)-5-isoquinolinesulphonamide] and HA-1004[N-(2-guanidinoethyl)-5-isoquinolinesulphonamide], inhibitors of cAMP-dependent protein kinase (PKA), attenuated the ability of forskolin to inhibit the 5-HT-stimulated accumulation of IPs. These results suggest that activation of cAMP/PKA was involved in these inhibitory effects of forskolin. The AlF₄ ⁻-induced accumulation of IPs was inhibited by forskolin, suggesting that G protein(s) are directly activated by AlF₄ ⁻- and uncoupled from phospholipase C by forskolin treatment. These results suggest that activation of cAMP/PKA might inhibit the 5-HT-stimulated phosphoinositide breakdown and consequently reduce the [Ca²⁺]_i increase or inhibit both responses independently. Received: 14 March 1996/Accepted: 10 April 1996     

Intrastriatal infusions of methoctramine improve memory in cognitively impaired aged rats

Alterations of striatal cholinergic markers may correlate with cognitive impairments in aged rats. M2 muscarinic receptors were found to be presynaptic inhibitory autoreceptors on striatal cholinergic interneurons. The effect of bilateral intrastriatal infusions of the M2 muscarinic receptor antagonist methoctramine was assessed, in cognitively impaired aged (24-26 months) Long-Evans female rats, on memory performances in a water maze. Compared with vehicle infusions, methoctramine injected bilaterally (1 microg/side) in the dorsolateral striatum, significantly improved procedural memory performance while having no effect on spatial working memory. Our results suggest that, in cognitively impaired aged rats, the blockade of M2 muscarinic receptors in the dorsolateral striatum improves procedural memory probably by enhancing the release of acetylcholine.     

ASK1 associates with troponin T and induces troponin T phosphorylation and contractile dysfunction in cardiomyocytes

There is increasing support for the idea that excessive production of proinflammatory mediators such as tumor necrosis factor (TNF) and reactive oxygen species (ROS) contribute to the pathogenesis of cardiac dysfunction. However, the mechanisms by which cytokine/ROS production mediates cardiac dysfunction have not been established. Given that apoptosis signal-regulating kinase 1 (ASK1) is highly expressed in cardiac muscle and that ASK1 is an important mediator in the signaling pathways induced by tumor necrosis factor, interleukin-1, and ROS, we used the yeast two-hybrid system with ASK1 as bait to identify ASK1 substrates from a human heart cDNA library. The cDNA encoding the cardiac troponin T (cTnT) was isolated. ASK1 specifically interacted with cTnT, but not cTnI, in vitro and in vivo via the C-terminal ASK1 domain. ASK1 specifically phosphorylated cTnT in vitro and in vivo. Mutations in cTnT (T194/S198) at an ASK1-phosphorylation consensus sequence significantly reduced phosphorylation by ASK1. ROS-induced ASK1 activation, cTnT phosphorylation, and contractile dysfunction in cardiomyocytes showed similar kinetics. Moreover, overexpression of constitutively active ASK1 induces cTnT phosphorylation and inhibits shortening and calcium transient in adult cardiomyocytes. We conclude that ASK1 plays an important role in regulation of cardiac contractile function by phosphorylating cTnT and may participate in cytokine/ROS-induced pathogenesis of cardiomyopathy and heart failure.     

Preparation and characterization of Pertussis toxin subunits

Pertussis toxin (PT), a typical A-B oligomer exotoxin of Bordetella pertussis, has been demonstrated to be an essential protective antigen for acellular pertussis vaccine against whooping cough. In order to investigate the associated functionality ascribed to its components, we have purified A and B oligomers for the activity study. The A oligomer (S1 subunit) of PT was expressed in E. coli B834 (DE3) harboring expression vector (pET-20b) with the insert of S1 coding region and purified by metal-chelating column. The B oligomer was isolated by a single-step purification procedure. Individually, recombinant S1 and B oligomer exhibited quite distinct biological activities in vivo. S1 subunit induced leukocytosis-promoting (LP) activity, but did not affect mouse body weight-gain. On the contrary, B oligomer reduced mouse body weight-gain but did not reveal LP activity. In vitro, the combination of S1 subunit and B oligomer could enhance the toxic activities as exhibited by native PT and showed an additive toxicity in CHO cell clustering test and hemagglutination assay.     

Small epithelial cells in human liver cirrhosis exhibit features of hepatic stem-like cells: immunohistochemical,electron microscopic and immunoelectron microscopic findings

AIMS: To investigate whether cells with features similar to those of the oval cells of rodents and the small epithelial cells (SEC) recently described in certain human liver diseases, i.e. hepatic progenitor cells, also occur in human liver cirrhosis. METHODS AND RESULTS: Surgical specimens from 35 cases of hepatitis B virus-positive cirrhosis (30 cases containing hepatocellular carcinoma) were investigated by immunohistochemical staining for cytokeratin 7 and albumin. Electron microscopic investigations, and immunoelectron microscopic investigations using the same antibodies and a double-labelling technique were performed in 15 and seven cases, respectively. SEC were observed in proliferated bile ductules, at the margins of regenerating nodules and in the fibrous septa in all cases of cirrhosis. The SEC were morphologically similar to the SEC described previously, and to the oval cells seen in experimental hepatocarcinogenesis. They were characterized by their small size, oval shape, scanty electron-dense or electron-lucent cytoplasm, a high nucleo-cytoplasmic ratio, tonofilaments and intercellular junctions. Immunoelectron microscopy revealed that the SEC co-expressed cytokeratin 7 and albumin. Both relatively undifferentiated SEC and SEC with morphological and immunophenotypical signs of differentiation towards biliary epithelial cells and hepatocytes were found. CONCLUSIONS: SEC that exhibit morphological and immunophenotypical features of the SEC seen in certain other liver diseases are found in cirrhosis. These findings further support the hypothesis that a bipotent hepatic stem cell that may give rise to biliary epithelial cells and hepatocytes exists in the human liver.