An unusual clinical presentation of bilateral schizencephaly

Summary We present a case with a characteristic magnetic resonance image (MRI) of bilateral open-lipped schizencephaly and atypical clinical presentation. The patient is still alive and in good health in her forties, she has never presented seizures, and although the motor dysfunction is well correlated with cerebral lobe involvement, neurobehavioral dysfunction is not proportional to the MR image of the cerebral malformation.

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Un cas inhabituel de schizencéphalie bilatérale

Résumé Nous présentons un cas de schizencéphalie bilatérale ouverte caractérisé par une présentation clinique atypique et une imagerie par résonance magnétique nucléaire caractéristique. La patiente est encore vivante, en bonne santé, à plus de 40 ans, elle n'a jamais présenté de crise comitiale et, bien que les troubles moteurs soient bien corrélés aux altérations cérébrales, les troubles neuro-comportementaux ne sont pas proportionnels aux images IRM de cette malformation cérébrale.

     

Age-related changes in adrenergic neuronal function of rabbit vascular smooth muscle

The adrenergic control of vascular smooth muscle was compared in young and adult rabbits using a variety of in vitro techniques. Norepinephrine (NE) content and accumulation of ³H-NE were not different in blood vessels from the two age groups. In contrast, stimulation-evoked release of endogenous NE was reduced by 40–60% in vessels from the aged animals. Functional studies of smooth muscle contractions were carried out using isolated ring segments of the ear artery. There were no differences in the resting force-response relationship between vessels from young and adult rabbits. Maximum contractile responses to nerve stimulation, NE or KCl were not different in vessels from the two age groups, nor was the NE ED₅₀. However, blockade of the neuronal uptake system with desmethylimipramine produced a greater shift in the NE concentration-response curve in vessels from the young animals compared to the shift in vessels from adult animals. This observation reflects a decline in neuronal NE uptake with age. Although maximal contractile responses to transmural nerve stimulation at 16 Hz were unchanged, responses to stimulation at lower frequencies were reduced in vessels from adult rabbits, an effect which was also enhanced when an antagonist of neuronal uptake was present. Thus, there is a decline in function of adrenergic nerves in adult animals, reflected in a decrease in stimulation-evoked NE release and a decrease in norepinephrine uptake revealed by functional studies. These two effects tend to balance each other, so that there is a small decrease in contractile response to adrenergic nerve stimulation which is exacerbated when neuronal uptake mechanisms are blocked.     

Malaria transmission and naturally acquired immunity to PfEMP-1

Why there are so few gametocytes (the transmission stage of malaria) in the blood of humans infected with Plasmodium spp. is intriguing. This may be due either to reproductive restraint by the parasite or to unidentified gametocyte-specific immune-mediated clearance mechanisms. We propose another mechanism, a cross-stage immunity to Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP-1). This molecule is expressed on the surface of the erythrocyte infected with either trophozoite or early gametocyte parasites. Immunoglobulin G antibodies to PfEMP-1, expressed on both life cycle stages, were measured in residents from an area where malaria is endemic, Papua New Guinea. Anti-PfEMP-1 prevalence increased with age, mirroring the decline in both the prevalence and the density of asexual and transmission stages in erythrocytes. These data led us to propose that immunity to PfEMP-1 may influence malaria transmission by regulation of the production of gametocytes. This regulation may be achieved in two ways: (i) by controlling asexual proliferation and density and (ii) by affecting gametocyte maturation.     

Energy deficiency,calcium overload or oxidative stress: Possible causes of irreversible ischemic myocardial injury

Summary After prolonged ischemia or hypoxia myocardial injury is not reversed but exacerbated by a resupply of the tissue with oxygen and substrates. The mechanism by which reversible ischemic or hypoxic myocardial injury becomes irreversible is not yet understood. It has been debated whether reperfusion injury merely uncovers pre-existing irreversible injury, or is indeed caused by the reperfusion/reoxygenation process. In recent years, three theories have been discussed that relate the onset of irreversibility either to: a critical energy loss; a critical accumulation of cellular calcium; or to the deleterious effects of free radical formation. In certain experimental models for each of these theories favourable results have been obtained. Current research suggests that absolute reversibility thresholds in energy depletion or calcium accumulation in the ischemic or hypoxic cell do not exist. A key role of free radical injury for reperfusion injury must also be questioned. There is, however, evidence that in tissue reversibility of ischemic cardiomyocyte injury is limited by conditions that make calcium-induced hypercontracture upon reoxygenation unavoidable. This occurs when, by hypercontracture, mutual mechanical disruption of the cells destroys the tissue. From isolated cardiomyocytes that are able to metabolically survive hypercontracture it has been observed that these metabolic conditions do not represent the last biological possibility to reverse injury.     

Apoptotic cell death in mouse models of GM2 gangliosidosis and observations on human Tay-Sachs and Sandhoff diseases

Tay-Sachs and Sandhoff diseases are autosomal recessive neurodegenerative diseases resulting from the inability to catabolize GM2 ganglioside by beta-hexosaminidase A (Hex A) due to mutations of the alpha subunit (Tay-Sachs disease) or beta subunit (Sandhoff disease) of Hex A. Hex B (beta beta homodimer) is also defective in Sandhoff disease. We previously developed mouse models of both diseases and showed that Hexa-/- (Tay-Sachs) mice remain asymptomatic to at least 1 year of age while Hexb-/- (Sandhoff) mice succumb to a profound neurodegenerative disease by 4-6 months of age. Here we find that neuron death in Hexb-/- mice is associated with apoptosis occurring throughout the CNS, while Hexa-/- mice were minimally involved at the same age. Studies of autopsy samples of brain and spinal cord from human Tay-Sachs and Sandhoff diseases revealed apoptosis in both instances, in keeping with the severe expression of both diseases. We suggest that neuron death is caused by unscheduled apoptosis, implicating accumulated GM2 ganglioside or a derivative in triggering of the apoptotic cascade.      

Low resting potentials in single isolated heart cells due to membrane damage by the recording microelectrode

Single myocytes from adult rat hearts were prepared following the method of Powell and co-workers (9, 10, 11). Low resting potentials (E_m) could be improved by three techniques. (i) Elevation of Ca_o to 7.2 mM which, however, mostly resulted in spontaneity and irreversible contracture. (ii) Pre-incubation in a KB medium (6). (iii) Use of suction pipettes instead of tapered microelectrodes for intracellular recordings (2). It is concluded that low E_m measured previously (11) were due to membrane damage upon microelectrode impalement accopanied by insfufficient healing of the membrane around the electrode insertion.     

Anatomic bases for liver transplantation

Summary This study gathers the anatomic implications for a good liver transplantation. During hepatic removal a left hepatic a.exists in 20% of cases; a right hepatic artery originating from the superior mesenteric a. (SMA) can be the only arterial supply in 9% of cases; the whole lesser omentum has to be removed and the SMA from 6 cm to its origin. The SMA must be freed from the celiac ganglia and its ostium removed with the celiac trunk in an aortic patch cut on the anterior side in order to avoid the renal ostia. During total hepatectomy, dissection of the portal triad is often difficult because of portal hypertension dilating accessory portal veins (parabiliary arcade) and pedicular lymphatics. Nerve plexuses are thick in front of the hepatic artery or behind the portal triad. Transection of triangular ligaments leads to the retrohepatic inferior vena cava (IVC) that must be freed from its posterior tributaries (right suprarenal vein and inferior phrenic veins flowing either into the IVC or into the hepatic veins). One big problem during hepatic replacement is the biliary anastomosis which must be well irrigated. In the recipient, dissection up to the hilum preserves hepatic and pancreatico-duodenal pedicles. The biliary tract of the graft must be cut low, behind the pancreas, and several centimeters of the gastroduodenal artery must be preserved to save hepatic and gastroduodenal pedicles.

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Bases anatomiques de la transplantation hépatique

Résumé Ce travail rassemble les notions anatomiques nécessaires au bon déroulement d'une transplantation hépatique. Le prélèvement du greffon doit enlever tout le petit omentum contenant une éventuelle a. hépatique gauche née de l'a. gastrique gauche (20%) et emporter l'a. mésentérique supérieure jusqu'à 6 cm de son origine pour ne pas oublier une a. hépatique droite née de cette dernière: son ostium est pris avec le tronc clique dans un patch aortique découpé sur la face antérieure. Lors de l'hépatectomie totale, la dissection du pédicule hépatique est rendue délicate par l'hypertension portale qui dilate les veines portes diets accessoires (arcade parabiliaire) et les lymphatiques pédiculaires. Les plexus nerveux sont riches devant l'artère hépatique et derrière le pédicule. La section des ligaments triangulaires droit et gauche amène à la veine cave inférieure (VCI) rétro-hépatique qu'il faut libérer de ses afférences postérieures (en particulier la veine surrénale principale droite toujours haut située et les veines phréniques inférieures qui s'abouchent soit dans la VCI soit dans les veines hépatiques du carrefour). Lors du remplacement, l'anastomose biliaire doit être vascularisée. Chez le receveur la dissection jusqu'au hile permet de conserver les pédicules. La voie biliaire du greffon doit être coupée bas derrière le pancréas et les premiers centimètres de l'artère gastro-duodénale conservés pour préserver les pédicules hépatique et pancréaticoduodénal.

     

The ileoanal J pouch: radiographic evaluation

Endorectal ileoanal pull-through offers an attractive alternative to proctocolectomy and ileostomy for patients with ulcerative colitis, Gardner syndrome, and familial polyposis. To our knowledge, a careful radiographic analysis of the ileum, ileal pouch, and ileoanal anastomosis after ileoanal pull-through has not been reported. Thirty-two patients with ulcerative colitis, Gardner syndrome, and familial polyposis underwent colectomy, mucosal proctectomy, and endorectal ileoanal pull-through of a 15-cm ileal "J" pouch and loop ileostomy. Twenty-five (78%) of 32 of all the pouches radiographically demonstrated spiral folds extending from the middle of the pouch to the pectinate line. Other radiographic features included a mesenteric mass effect, pseudopolyps, and a central lucency that indicated intrapouch sutures. Radiographs provide useful information in the postoperative management of the ileal pull-through.