Effects of PACAP on intracellular signaling pathways in human retinal pigment epithelial cells exposed to oxidative stress.

The integrity of retinal pigment epithelial cells is critical for photoreceptor survival and vision. Pituitary adenylate cyclase activating polypeptide (PACAP) exerts retinoprotective effects against several types of injuries in vivo, including optic nerve transection, retinal ischemia, excitotoxic injuries, UVA-induced lesion, and diabetic retinopathy. In a recent study, we have proven that PACAP is also protective in oxidative stress-induced injury in human pigment epithelial cells (ARPE-19 cells). The aim of the present study was to investigate the possible mechanisms of this protection. ARPE cells were exposed to a 24-h hydrogen peroxide treatment. Expressions of kinases and apoptotic markers were studied by complex array kits and Western blot. Oxidative stress induced the activation of several apoptotic markers, including Bad, Bax, HIF-1α, several heat shock proteins, TNF-related apoptosis-inducing ligand, and Fas-associated protein with death domain, while PACAP treatment decreased them. The changes in the expression of MAP kinases showed that PACAP activated the protective ERK1/2 and downstream CREB, and decreased the activation of the pro-apoptotic p38MAPK and c-Jun N-terminal kinase, an effect opposite to that observed with only oxidative stress. Furthermore, PACAP increased the activation of the protective Akt pathway. In addition, the effects of oxidative stress on several other signaling molecules were counteracted by PACAP treatment (Chk2, Yes, Lyn, paxillin, p53, PLC, STAT4, RSK). These play a role in cell death, cell cycle, inflammation, adhesion, differentiation and proliferation. In summary, PACAP, acting at several levels, influences the balance between pro- and anti-apoptotic factors in favor of anti-apoptosis, thereby providing protection in oxidative stress-induced injury of human retinal pigment epithelial cells.

TIP47 protects mitochondrial membrane integrity and inhibits oxidative-stress-induced cell death.

We found that overexpression of tail interacting protein of 47 kDa (TIP47), but not its truncated form (t-TIP47) protected NIH3T3 cells from hydrogen-peroxide-induced cell death, prevented the hydrogen-peroxide-induced mitochondrial depolarization determined by 5,50,6,60-tetrachloro-1,10,3,30-tetraethyl-benzimidazolylcarbocyanine iodide (JC1), while suppression of TIP47 in HeLa cells facilitated oxidative-stress-induced cell death. TIP47 was located to the cytoplasm of untreated cells, but some was associated to mitochondria in oxidative stress. Recombinant TIP47, but not t-TIP47 increased the mitochondrial membrane potential (Deltapsi), and partially prevented Ca2+ induced depolarization. It is assumed that TIP47 can bind to mitochondria in oxidative stress, and inhibit mitochondria mediated cell death by protecting mitochondrial membrane integrity.

Improved pulmonary adaptation in newborn calves with postnatal acidosis.

The adaptation of newborn calves to extra-uterine life was evaluated by measuring arterial blood gases, acid-base values, blood ions and lung mechanical function parameters in normal and acidotic calves during the first 24 h. Twenty-seven Holstein Friesian newborn calves were divided into two groups according to their immediate post partum arterial blood pH values (Group A blood pH > or = 7.2: normal group; Group B blood pH between 7.2 and 7.0: acidotic group). Pulmonary function parameters were measured and arterial blood samples were analysed for blood gases, acid-base variables and ion content immediately post partum (within 2 min) and then 6 and 24 h after calving. Lung resistance and maximal difference between pressure maximum and pressure minimum (max delta Ppl) decreased, while dynamic lung compliance increased significantly in both groups. Immediately post partum the lung resistance and max delta Ppl were significantly higher in the acidotic group than in the normal group. The arterial blood pH progressively compensated with time in both groups during the first 24 h and there was no difference in arterial blood pH values between the two groups 6 h after birth. These results showed that the compensation of acidosis was associated with the improvement in lung mechanics and these changes occurred mainly during the first 6 h of life. Moderate to pronounced acidosis did not affect the pulmonary adaptation negatively, although some respiratory mechanics parameters (max delta Ppl), blood pH and Ca(2+)ion concentrations remained significantly different between the normal and acidotic groups at 24 h. This might be the result of overcompensation of acidosis and the interdependence between blood pH and Ca(2+)concentrations.

Endocrinology of pregnancy: chorionic somatomammotropins and pregnancy-associated glycoproteins: review.

The two main groups of placental proteins of ruminants are discussed in this paper: chorionic somatomammotropins (placental lactogens) and pregnancy-specific (-associated) proteins. Placental lactogens belong to the prolactin and growth hormone family. They stimulate mammogenesis, fetal growth and maternal metabolism. Pregnancy-specific proteins and pregnancy-associated glycoproteins belong to the aspartic proteinase family like pepsin, cathepsin D and E. These two groups of proteins are secreted in the maternal circulation by the binucleate cells after their migration to and fusion with the uterine cells. Their profiles were determined by radioimmunoassay (RIA). Further investigations are in progress to relate secretory profiles with alterations of the trophoblastic function such as those occurring in embryonic mortality, abortion, and fetal distress. The endocrine function of the primate and equine placenta is also discussed.

Differential Electrophysiologic Effects of Chronically Administered Amiodarone on Canine Purkinje Fibers versus Ventricular Muscle.

BACKGROUND: Acute and chronic treatment with amiodarone has been reported to cause different electrocardiographic changes in patients. The cellular electrophysiologic effects of chronic administration (50 mg/kg/day orally for 6 weeks) and acute superfusion (5 µM in the tissue bath) of amiodarone were therefore studied in dog cardiac ventricular muscle and Purkinje fibers using conventional microelectrode techniques. METHODS AND RESULTS: During stimulation at 1 Hz, chronic amiodarone treatment lengthened the ventricular muscle action potential duration (APD) from 227.8 +/- 6.3 ms (n = 20) to 262.3 +/- 5.2 ms (n = 21; P <.01), but shortened that of Purkinje fibers from 337.6 +/- 9.2 (n = 21) to 308.3 +/- 7.1 (n = 19; P <.05). Acute superfusion of 5 µM amiodarone in cardiac tissue obtained from chronically treated dogs did not change ventricular muscle APD but shortened Purkinje fiber AP from 309.7 +/- 13.6 ms to 281.9 +/- 11.9 ms (n = 8; P <.05). Neither the chronic nor the acute amiodarone exposure prevented the APD shortening in ventricular muscle evoked by 10 µM pinacidil, suggesting that amiodarone does not interfere with the ATP-dependent potassium channels. The normal difference in APD between ventricular muscle and Purkinje fibers in untreated, control preparations was 110 ms but decreased to 46 ms in fibers obtained from dogs chronically treated with amiodarone and increased to 185 ms in fibers obtained from dogs chronically treated with amiodarone and increased to 185 ms in the presence of 30 µM sotalol, a class III antiarrhythmic drug used for comparison. Amiodarone (5 µM) applied directly abolished early afterdepolarizations (EADs) (induced by 1 µM dofetilide + 20 µM BaCl(2) + 2 mM CsCl) in 5 of 6 experiments and caused strong use-dependent V(max) block with relatively fast onset kinetics (rate constant = 1.23 +/- 0.13 AP(-1), n = 5) and offset (time constant = 364 +/- 62.5 ms, n = 5). After chronic amiodarone treatment, in contrast with acute sotalol application (30 µM), no reverse use-dependent effect was observed on the APD in Purkinje fibers. CONCLUSIONS: These results provide further evidence that amiodarone differs from other recognized class III antiarrhythmic drugs (ie, it is a mixed type agent with acute fast kinetic class I [type B] and a unique class III antiarrhythmic action characterized by decreased dispersion of APDs between ventricular muscle and Purkinje fibers). Amiodarone can abolish EADs unlike other class III agents that are usually associated to induction of EADs. These features might be responsible not only for the antiarrhythmic efficacy, but also for the relative safety (low incidence of torsade de pointes) of amiodarone in clinical settings.

Effect of deoxyfructoserotonin (DFS) on lepromatous leprosy.

To examine the anti-leprosy effect of deoxyfructoserotonin the drug was given in a dose of 10 mg/kg for 6 months to 6 patients with active lepromatous leprosy, in accordance with the WHO-THELEP protocol. Clinical and histological assessment and mouse foot-pad studies suggest that the drug has some anti-leprosy effect.

Mouse foot-pad studies with M. leprae--effect of desoxy fructo serotonin (DFS) and related compounds.

Mouse foot-pad experiments were carried out to study the effects of DFS and related compounds on the multiplication of M. leprae. Of the 25 cases clinically suspected Dapsone resistance, 8 were found resistant and 14 sensitive to Dapsone by mouse foot-pad experiments. Six were resistant to DFS and 16 were sensitive. Desoxy fructo 5-hydroxy tryptophane as well as Nutrition Antileprosy (NAL) diet were also found effective in suppressing the growth of M. leprae in mouse foot-pad. Of the two liposoluble derivatives of DFS tested (DFS LS-I and DFS LS-II), DFS LS-II was found more effective in suppressing the growth of M. leprae in foot-pads of mice.

A new antagonist of the 5-hydroxytryptamine receptor of blood platelets.

The newly synthesized 1-desoxyfructo-alpha,beta-dehydro-4, 5-dioxotryptamine (M4) inhibited the 5-hydroxytryptamine (5-HT)-induced shape-change reaction of human and rabbit platelets and to a lesser extent the adenosine-3',5'-diphosphate-induced shape-change reaction of rabbit platelets. The 5-HT-antagonism was shown to be of the competitive type in human platelets. In the latter M4 also counteracted the 5-HT-uptake, but was virtually ineffective in releasing 5-HT. Another new derivative of desoxyfructo-5-HT (M5) was a 5-HT-agonist. It is concluded that M4 represents a new class of antagonists of 5-HT-receptors in platelets.

Low serotonin uptake by platelets in leprosy and a new approach to prevent it.

The plasma of leprosy patients contains high levels of mucoproteins which are deficient in sialic acid. However, due to the increased mucoprotein level, the total sialic acid content of leprous plasma, calculated on protein, is increased when compared with normal human plasma. The low serotonin uptake observed with isolated platelets is probably due to their low sialic acid content. The inability of normal human plasma to correct the diminished serotonin uptake by isolated leprous platelets is in favor of a definite structural change in leprous platelets, related to their low sialic acid content. In patients with active disease and in those with lepra reactions, leprous plasma itself can correct the diminished uptake of serotonin by the isolated platelets. In patients with subsided lepra reactions, the leprous plasma is much less effective. In severe cases, where serotonin uptake is decreased even in platelet rich plasma, desoxyfructo-serotonin increased the uptake of serotonin.