Retransplantation of the liver after side-to-side caval anastomosis

Caval reconstruction in orthotopic liver transplantation is generally performed by two end-to-end anastomoses, using a portal and caval-axillary bypass to sustain hemodynamic stability. In the piggyback modification, the donor's suprahepatic inferior vena cava (IVC) is anastomosed end-to-side to the recipient's preserved IVC. We have used a recently described variant of the piggyback in 18 patients in whom both IVCs are anastomosed side-to-side. We report two patients who needed three retransplants after this reconstruction and conclude that regrafting can be performed in a quick and safe manner.     

Cytogenetic analysis of human oocytes parthenogenetically activated by puromycin

Purpose

Treatment of aged human oocytes by puromycin allows a high rate of parthenogenetic activation and development until the first cleavage division. This technique was used for the study of the chromosome complement of oocytes which remained unfertilized after in vitro fertilization. Three hundred four unfertilized oocytes were treated with 10 Μg/ml puromycin for 6–8 hr and further cultured for 12–15 hr.

Results

Activation occurred in 90.5% of the oocytes. Heterozygous diploids with two pronuclei predominated (61%), which is in contrast to the mouse, where the majority of oocytes activated by puromycin are uniform haploids (89%).

Conclusions

Therefore we conclude that puromycin treatment induces retention of the second polar body in human oocytes, unlike in mouse oocytes treated in the same way. Chromosome analysis performed on 182 oocytes suggested a nondisjunction (ND) rate for the second meiotic division of 12.7%. This is a low figure considering the fact that puromycin itself has been reported to induce nondisjunction. For the first meiotic division a ND rate of only 5.6% was found. This rate is lower than the one found in metaphase II arrested oocytes and we believe that this difference is due to the technical differences between the study of meiotic and that of mitotic chromosomes.     

Role of Nr13 in regulation of programmed cell death in the bursa of Fabricius

Apoptotic cell death is developmentally regulated in the chicken bursa of Fabricius. Although apoptosis is low in the embryonic bursa, cell death increases markedly after hatching. The expression of Bcl2 family cell death antagonists was examined to identify the genes that regulate bursal cell apoptosis. The expression of Bcl-xL, A1, and Mcl1 was detected in both embryos and hatched birds, whereas Nr13 was expressed at high levels in embryonic bursa, and decreased significantly after hatching, correlating inversely with apoptosis. The oncogene v-reland phorbol myristate acetate, two known inhibitors of bursal cell apoptosis, induced Nr13 expression. Overexpression of Nr13 in DT40 bursal lymphoma cells protected them from low serum-induced apoptosis. The mechanism of inhibition of apoptosis by Nr13 is likely to involve a critical BH4 domain and interaction with death agonist Bax. Deletion of the BH4 domain converted Nr13 into a death agonist. Bax coimmunoprecipitated with Nr13 and Bax was induced, whereas Nr13 levels diminished when bursal lymphoblasts were induced to apoptosis by dispersion. Bursal transplantation studies demonstrated that Nr13 could prevent the in vivo programmed elimination of bursal stem cells after hatching, suggesting that Nr13 plays a role in maintaining bursal stem cells.     

Nitric Oxide and -Arginine Cause an Accumulation of Utrophin at the Sarcolemma: A Possible Compensation for Dystrophin Loss in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD), a severe X-linked recessive disorder which results in progressive muscle degeneration, is due to a lack of dystrophin, a membrane cytoskeletal protein. An approach to treatment is to compensate for dystrophin loss with utrophin, another cytoskeletal protein with over 80% homology with dystrophin. Utrophin is expressed, at the neuromuscular junction, in normal and DMD muscles and there is evidence that it may perform the same cellular functions as dystrophin. So, the identification of molecules or drugs that could up-regulate utrophin is a very important goal for therapy. We show that in adult normal and mdx mice (an animal model of Duchenne myopathy) treated with -arginine, the substrate of nitric oxide synthase (NOS), a pool of utrophin localized at the membrane appeared and increased, respectively. In normal and mdx myotubes in culture, -arginine, nitric oxide (NO), or hydroxyurea increased utrophin levels and enhanced its membrane localization. This effect did not occur with -arginine, showing the involvement of NOS in this process. The NO-induced increase in utrophin was prevented by oxadiazolo-quinoxalin-1-one, an inhibitor of a soluble guanylate cyclase implicated in NO effects. These results open the way to a potential treatment for Duchenne and Becker dystrophies.     

A method for the follow-up of clusters of adverse reproductive outcomes

Clusters of adverse reproductive outcomes are reported with increasing frequency to public health authorities. Most are random events and only a very small proportion is likely due to identifiable environmental agents. Often, a preliminary study confirms the existence of a spatial and temporal excess but no biologically plausible cause is found. These cases require a follow-up of incidence to identify any continuing excess. A conceptually simple fixed window technique of follow up is proposed. The power of the test is mainly influenced by the magnitude of the increase in rate, the number of adverse outcomes selected for observation and the acceptable false alarm rate. This technique has several advantages compared with other currently used methods. From a public health point of view, two important factors are to be considered in setting the parameters of the test: the delay in providing an answer for the community and the availability of resources for conducting environmental investigations.     

Investigation of clusters of adverse reproductive outcomes, an overview

Clusters of adverse reproductive outcomes are reported with increasing frequency to public health services, but it is likely that only a minority of clusters are caused by a common environmental teratogen or mutagen. Many guidelines and protocols have been developed for the investigation and the management of chronic disease clusters and can be applied to the study of adverse reproductive outcomes. Cluster investigation normally follows four successive phases: (i) the generation of one or more etiologic hypotheses, (ii) the confirmation of the hypotheses, (iii) an intervention aimed at reducing any dangerous exposure, and (iv) the evaluation of the effect of the intervention. However, each situation is unique and there is no standard recipe for conducting the epidemiologic investigation at each successive phase, for choosing the appropriate statistical technique and for communicating with interested parties. In order to minimize both the risk of pursuing a worthless investigation and the risk of ignoring a real excess of cases caused by an adverse environmental factor, it is imperative to rely on a team of specialists with expertise in epidemiology, statistics, toxicology, embryology, and communication.     

Oxolinic acid and diazepam: Their reciprocal antagonism in rodents

The stimulant effects of oxolinic acid were investigated in rats and mice. This drug, given orally, consistantly induced, in doses ranging from 16 to 256 mg·kg^-1, locomotor stimulation and stereotyped behavior.These effects were antagonized by pimozide (1 mg·kg^-1), -methyltyrosine (64 mg·kg^-1) or reserpine (4 mg·kg^-1, 24 h before testing) pretreatment, suggesting a facilitatory role of oxolinic acid on catecholaminergic processes.Diazepam (4–16 mg·kg^-1) reduced the stimulant effects induced by oxolinic acid but not those induced by amphetamine; oxolinic acid (8 mg·kg^-1) markedly reduced the antipunishment effect elicited in rats by diazepam (2 mg·kg^-1). Since benzodiazepines have been reported to enhance GABA functioning, these data suggest that oxolinic acid may impair GABA transmission. However, neither muscimol (0.5–1 mg·kg^-1) or -acetylenic-GABA (16–64 mg·kg^-1) selectively reduced the stimulant effects elicited by oxolinic acid. Therefore, the possible facilitation exerted by this drug on catecholaminergic systems may not derive from the release of an inhibitory GABAergic control.     

The effect of arachidonic acid on the M current of NG108-15 neuroblastoma × glioma hybrid cells

The M current, I _M, a voltage-dependent non-inactivating K⁺ current, was recorded in NG108-15 neuroblastoma × glioma hybrid cells, using the whole-cell mode of the patch-clamp technique. We studied the effect of arachidonic acid, other fatty acids and inhibitors of the arachidonic acid metabolism. In relatively high concentrations (25–50 M) arachidonic acid first increased and later decreased the current, I _h, which holds the membrane potential at –30 mV and mainly flows through open M channels. It shifted the midpoint potential, V _o, of the relation between M conductance, g _M, and membrane potential, V, to more negative values and decreased the maximum conductance ¯g _M and the time constant _M. In smaller concentrations (5–10 M) arachidonic acid merely decreased I _h and ¯g _M with little effect on V _o and _M. Eicosatetraynoic acid and docosa-hexaenoic acid acted similarly to arachidonic acid whereas stearic acid had no effect. Of the three enzyme inhibitors studied, nordihydroguaiaretic acid acted similarly to arachidonic acid. i. e. caused a biphasic change in I _h. Indomethacin and quinacrine caused, respectively, a pure increase and a pure decrease of I _h and ¯g _M. Possible explanations are build-up of internally produced arachidonic acid, depletion of eicosanoid products or an inhibitory effect unrelated to arachidonic acid metabolism.     

Synergistic Regulation of Cytosolic Ca2+ Concentration by Adenosine and alpha1-Adrenergic Agonists in Mouse Striatal Astrocytes

Adenosine has a broad array of actions on neurons but astrocytes also possess adenosine receptors. We have previously shown that adenosine, by acting on astrocytes in the striatum, can modulate neuronal responses mediated by receptors coupled to phospholipase C through an astrocyto - neuronal interaction. In addition, adenosine was found to potentiate the alpha1-adrenergic production of inositol phosphates in astrocytes. The mechanism involved in this potentiation was further investigated by examining the effects of adenosine and alpha1-adrenergic receptor agonists on cytosolic Ca2+ in cultured striatal astrocytes from the embryonic mouse in primary culture. When used alone, methoxamine, a selective agonist of alpha-adrenergic receptors or 2-chloroadenosine, a stable analogue of adenosine, induced a transitory increase in cytosolic Ca2+, but their combined addition led to a sustained increase in cytosolic Ca2+, which seems to be due to a Ca2+ influx, because it was not observed in the absence of external Ca2+. Voltage independent Ca2+ channels contribute to this process and different blockers of voltage-operated calcium channels, such as dihydropyridines, phenylalkylamines, La3+ or Co2+ were ineffective in suppressing the sustained cytosolic Ca2+ elevation. Three observations suggest the implication of arachidonic acid in the observed potentiation: (i) arachidonic acid induced a sustained elevation of cytosolic Ca2+ similar to that evoked by the coapplication of methoxamine and 2-chloroadenosine; (ii) the addition of arachidonic acid during the calcic plateau produced by the combined application of the agonists did not increase further cytosolic Ca2+ levels; (iii) in the presence of methoxamine, 2-chloroadenosine induced a release of arachidonic acid. The stimulation of phospholipase C and the resulting activation of protein kinase C induced by methoxamine seem to be required for the potentiating effect of 2-chloroadenosine on cytosolic Ca2+. In fact, the direct activation of protein kinase C by an exogenous diacylglycerol analogue mimicked the effect of methoxamine because, in this condition, 2-chloroadenosine alone evoked a sustained elevation of cytosolic Ca2+. Therefore, methoxamine, through the successive activation of phospholipase C and protein kinase C, could allow a lipase, probably phospholipase A2, to be stimulated by 2-chloroadenosine. Arachidonic acid has already been shown to trigger the opening of K+ channels and the formation of inositol phosphates in other cell types. Therefore, in striatal astrocytes, 2-chloroadenosine, through an arachidonic acid-mediated hyperpolarization, could increase the Ca2+ driving force and thus improve Ca2+ influx through inositol phosphate-gated channels. This hypothesis is further supported by the suppressing effect of a 50 mM KCI-induced depolarization on the long lasting elevation of cytosolic Ca2+ seen in the combined presence of 2-chloroadenosine and methoxamine.