Dementia and neurodevelopmental predisposition: cognitive dysfunction in presymptomatic subjects precedes dementia by decades in frontotemporal dementia.

Dementia is typically thought of as a disease caused by the process of aging. Few studies have addressed the premorbid neuropsychological alterations in subjects at risk for the disease--an issue of great importance for the understanding and treatment of degenerative dementias. We used knowledge of the mutation carrier status in a family with inherited dementia to address this issue more efficiently than is possible in the general population, or in cases of inherited dementia where the mutational basis is unknown. Standard neuropsychological tests were used to detect evidence of dysfunction in frontal executive systems in 10 presymptomatic subjects with known mutation carrier status in the highly penetrant condition, frontotemporal dementia and parkinsonism linked to chromosome 17. Presymptomatic carriers demonstrated cognitive dysfunction that was not present in 6 nonmutation-carrying relatives. Strikingly, frontal-executive dysfunction was apparent in some of the youngest mutation carriers many decades prior to the predicted onset of dementia. Thus, this dysfunction may reflect the native cognitive capacities of affected subjects. These results suggest a potentially important neurodevelopmental component to a dementing condition that has been predominantly considered to be a disease of aging; accordingly, this issue warrants study in other families to assess the applicability of these findings.

Implication of ATP and sodium in arachidonic acid incorporation by placental syncytiotrophoblast brush border and basal plasma membranes in the human.

The human placental syncytiotrophoblast is the main site of exchange of nutrients and minerals between the mother and her fetus. In order to characterize the placental transport of some fatty acids, we studied the incorporation of arachidonic acid, a fetal primordial fatty acid, in purified bipolar syncytiotrophoblast brush border (BBM) and basal plasma membranes (BPM) from human placenta. The basal arachidonic acid incorporation in BBM and BPM was time dependent and reached maximal values of 0.75+/-0.10 and 0.48+/-0.18 pmol/mg protein, respectively, after 2.5 min. The presence of adenosine triphosphate (ATP) (3 m m) increases significantly the maximal incorporation of arachidonic acid by sixfold (4.75+/-0.35 pmol/mg) and ninefold (4.40+/-0.84 pmol/mg) in BBM and BPM, respectively. Moreover, an increase in the arachidonic acid incorporation was also obtained in the presence of sodium where the values achieved 7.68+/-0.98 (10x) and 6.53 pmol/mg (13.6x) for BBM and BPM, respectively. We also showed that the combination of both Na(+)and ATP increases significantly the maximal incorporation of arachidonic acid in BPM to 7.89+/-0.15 pmol/mg protein, while in BBM it did not modify its incorporation (8.18+/-0.25 pmol/mg protein), as compared to the presence of sodium alone. Our results demonstrate that arachidonic acid is incorporated by both placental syncytiotrophoblast membranes, and is ATP and sodium-linked. However, different mechanisms seem to be involved in this fatty acid incorporation through BBM and BPM, since the presence of Na(+)or ATP increased it, while the association of these two elements increased it only in BPM. We also demonstrated by osmolarity experiments that both membranes bind arachidonic acid, potentially involving one or more fatty acids binding proteins.

Activation of L-type calcium channels induces corticotropin-releasing factor secretion from human placental trophoblasts.

The ultimate outcome of pregnancy, parturition, is a well orchestrated process in which placental corticotropin-releasing factor (CRF) seems to play an important role. The objective of the present study was to investigate the involvement of L-type calcium channels and calcium-dependent signaling in the depolarization-induced CRF release from human syncytiotrophoblast. The basal secretion of CRF by trophoblastic cells, isolated from human term placenta, was maximal after their functional differentiation, which was monitored by hCG measurements. On the fourth day of culture, the basal CRF secretion of the cells in serum-free medium was linear between 2 and 8 h. Incubation of the trophoblasts with KCl, a depolarizing stimulus, or with Bay K8644, an L-type calcium channel agonist, for 3 or 8 h led to an increase in CRF secretion, but was without effect on its synthesis. This stimulated CRF release was calcium dependent, as it could be prevented by loading cells with 1,2-bis(0-Aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (acetoxymethyl) ester. Furthermore, the KCl-induced CRF secretion involved L-type calcium channels activation, as 2 micromol/L nitrendipine, an L-type specific blocker, abolished the stimulation. In trophoblasts, where we have previously shown calcium-dependent protein kinase C (cPKCs) activity, incubation with Bay K8644 also stimulated calcium calmodulin kinase II (CaMKII) and extracellular regulated kinase activities. In the present study we observed that CaMKII and cPKCs were linked to the Bay K8644-induced secretion of CRF, as only the autocamtide-2 related inhibitory peptide, a CaMKII inhibitor, and Gö6976, an inhibitor of mu and cPKCs partially prevented (30-78%) the activation of CRF release by Bay K8644. The use of PD 098056, an inhibitor of the ERKs kinases, showed no effect on CRF release. Taken together, these results support a depolarization-induced and calcium-dependent exocytotic-like secretion of CRF from human placental trophoblasts. In addition, CaMKII and cPKCs seem to be potential modulators or mediators of these calcium effects on CRF secretion.

Characterization of neuropeptide Y-mediated corticotropin-releasing factor synthesis and release from human placental trophoblasts.

Neuropeptide Y (NPY) is a CRF secretagogue for human placental cells in culture. We have studied the involvement of intracellular calcium and calcium-dependent signaling in the NPY-induced CRF release in trophoblastic cells. The incubation of trophoblasts with NPY for 3 and 8 h led to a dose-dependent increase in CRF secretion. Also, NPY stimulated synthesis of this peptide hormone upon an 8-h incubation period. BIBP3226, a selective Y1 receptor antagonist, and pertussis toxin (PTX) eliminated these effects. NPY-stimulated CRF secretion was mostly prevented by loading cells with BAPTA-AM, suggesting that elevation of intracellular calcium is responsible for the increase of CRF secretion. However, this calcium chelator had no effect on CRF synthesis. Furthermore, U-73122, a phospholipase C-betas (PLC) inhibitor or xestospongin C, an inositol triphosphate receptor (InsP3-R) blocker, have partially prevented the effect of NPY on CRF synthesis and secretion. Therefore, the increase in CRF synthesis and secretion rely in part on the release of calcium from intracellular store. Interestingly, SKF 96365, an inhibitor of store operated calcium (SOC) influx, also partially blocked the NPY stimulatory effect on CRF release but not its synthesis, suggesting that calcium influx is also involved in this stimulation. In the syncytiotrophoblast, known to possess a NPY-activated protein kinase C (PKCs) activity, NPY also stimulated calcium calmodulin kinase II (CaMKII) and extracellular regulated kinase (ERK1/2) activities. In the present study, we observed that bisindolylmaleimide (BIM), a nonspecific PKCs inhibitor partially prevented the NPY-induced CRF release. On the other hand, autocamtide-2 related inhibitory peptide (AIP), a CaMKII inhibitor, prevented most of the stimulatory effect of NPY on both CRF synthesis and release. Go6976, an inhibitor of the conventional and mu PKCs and PD 098059, an inhibitor of the ERK cascade, had no effect on neither CRF synthesis nor release. Altogether, these results support a Y1 receptor-mediated PTX-sensitive induction on CRF synthesis and release by NPY from human placental trophoblasts. The stimulation of CRF synthesis by NPY seems to depend mainly on a PLC-beta to InsP3-R axis and on CaMKII activity. Also, the release of CRF depends on the PLC-beta to InsP3-R axis and CaMKII activity but also entails the participation of a calcium-independent PKCs.

Presence of CLA-1 and HDL binding sites on syncytiotrophoblast brush border and basal plasma membranes of human placenta.

It is now known that rapid placental and fetal development is associated with elevated levels of circulating high density lipoprotein (HDL) in pregnant women. The main structure implicated in the maternal-fetal exchange is the syncytiotrophoblast, composed of a brush border membrane (BBM), facing the mother, and a basal plasma membrane (BPM), facing the fetus. In order to understand the mechanisms controlling the placental and fetal supplies of cholesterol, we purified both BBM and BPM and verified the presence of HDL binding sites in these membranes. Binding studies using(125)I-HDL(3)show a single affinity binding site on BPM which has a dissociation constant (K(d)) of 3.45+/-0.43 microg protein/ml and a maximal binding capacity (B(max)) of 5.46+/-1.69 microg protein/mg membrane proteins. In BBM, we observed two affinity binding sites, one with a K(d)of 0.62+/-0.03 microg protein/ml and another one with a K(d)of 6.57+/-0.87 microg protein/ml. Their B(max)values were 0.54+/-0.11 and 2.34+/-0.39 microg of HDL(3)/mg membrane proteins, respectively. CLA-1, a putative HDL-receptor of 85 kDa, was detected on both BPM and BBM, together with two apo A-l binding sites of 110 and 96 kDa on BPM and BBM, respectively. These results provide further evidence that human placenta possesses specific sites for HDL binding, underlining the important role of maternal HDL in the transfer of cholesterol from the maternal circulation to the placenta and the fetus.

Absence of correlation between amobarbital distribution as assessed with SPECT brain perfusion imaging and behavioral manifestations during the intracarotid amobarbital procedure (Wada test).

1. The IAP is used presurgically in patients with temporal lobe epilepsy to predict the effects on LTM and language of the planned temporal lobectomy. This prognosis presumes that a similar pattern of perfusion will result in anesthesia of the same cerebral regions in most patients. 2. Coinjection of Tc-99m HMPAO with the barbiturate during the IAP has been used to ascertain whether this actually is true, with variable results. Moreover, most studies document only unilateral IAPs and do not report on behavioral performance. 3. The authors coinjected Tc-99m HMPAO and amobarbital in 33 IAPs from 18 patients (15 injected bilaterally, 3 unilaterally) to clarify this and to evaluate the relationship of the perfusion pattern to behavioral performance; SPECT results were also compared to angiographic evaluation obtained at the time of catheter placement. 4. SPECT perfusion data was rated for presence/absence and intensity of perfusion to the ACA, MCA, PCA territories and to H, i or c to the injection site. V, STM and LTM were graded according to a standardized protocol. 5. MCAi was perfused in 100% of cases, ACAi in 91%, PCAi in 21% and Hi in only 6%. Cross-over flow was shown in 9 studies; 50% of the patients in whom both sides were injected (on different days) had crossover, involving the ACAc territory in 80% of cases. As expected, injection on the non-ES was associated with a significantly worse LTM performance than on the ES (p = 0.006). There was no relationship between the perfusion pattern and the V level of the patients (a potential confounding variable in memory/language evaluation) during IAP, nor between perfusion pattern and LTM. STM was significantly adversely affected by the presence of crossover perfusion. Angiography in general overestimated the extent of cerebral perfusion demonstrated by SPECT, most probably because of the markedly different injection conditions. 6. Despite the best efforts to standardize injections, the perfusion pattern has been mostly unpredictable in the patients. Moreover, it has little bearing on their behavioral performance, except for the prediction of poor STM performance (the clinical implications of this remaining dubious). Marked LTM alterations after non-ES injections confirm remote hippocampal effects in the presence of only rare direct perfusion of that region. Tc-99m HMPAO/Amobarbital coinjection was unhelpful from a clinical perspective, most probably because a large part of the effects of amobarbital arise from deafferentation of regions not directly perfused by the anesthetic agent.

Human syncytiotrophoblast NPY receptors are located on BBM and activate PLC-to-PKC axis.

Neuropeptide Y (NPY) is abundant in plasma and amniotic fluid of women throughout pregnancy, during which its involvement in placental hormonogenesis has been proposed. In accordance with its putative role, the aim of this study was to characterize the human placental syncytiotrophoblast receptivity to NPY. Thus we performed this study on brush-border membranes (BBM) and basal plasma membranes (BPM). Specific 125I-labeled NPY (125I-NPY) binding to BBM was rapid (20 min), saturable, with a maximum binding capacity of 604 +/- 100 fmol/mg protein, and of high affinity, with a dissociation constant of 11 +/- 3 nM. No saturable binding could be shown in BPM. The rank order of affinity of NPY and related peptides to compete for 125I-NPY binding sites was peptides YY (PYY) > NPY = [Leu31,Pro34]NPY > 13-36NPY >> pancreatic polypeptide (PP). It is noteworthy that PYY displaced only 45% of the binding sites. In BBM, both NPY and PYY were potent phospholipase C (PLC) stimulators, leading to a four- to fivefold increase of control phosphodiesterase activity. The latter effect could be prevented by preincubation of membranes with 5 microM U-73122, a known inhibitor of G protein-linked receptor activation of PLC-beta. Furthermore, 5 microM BIBP-3226, a Y1-receptor antagonist, shifted both dose-response curves to the right in a similar fashion for both peptides. In accordance with the PLC stimulation, both peptides also induced stimulation of protein kinase C (PKC) activity, which could be partially but additively prevented by U-73122 and LY-294002, a selective inhibitor of phosphatidyl-inositol-3 kinase (PI3K). Taken together, these data suggest that placental and blood-derived NPY binds to a mixed population of receptors composed of Y1 and Y3 subtypes on the maternal side of the syncytiotrophoblast, where it can mediate its physiological purposes via PLC-beta and PI3K activation, both of which lead to PKC activation. However, because BIBP-3226 antagonized both effects, the physiological relevance of the apparent Y3 fraction is still unsolved.

Effect of focus lateralization on memory assessment during the intracarotid amobarbital procedure.

Despite the use of stimuli that can be processed by both hemispheres, a number of studies have reported lower memory scores after the left intracarotid amobarbital procedure (IAP) than after the right IAP. Because of that, failure after ipsilateral IAP is observed more often in patients with a left temporal seizure focus (LT) than in right temporal patients (RT), possibly needlessly excluding some LT patients from surgery. In order to overcome the deleterious effects of anesthetizing the dominant hemisphere, we designed an IAP protocol that did not promote verbal encoding of the stimuli. For this purpose, a large number of visual and tactile stimuli (colored pictures and real objects) were presented to be recognized later. The effect of seizure focus lateralization was examined in 82 temporal lobe epileptic patients who underwent IAP as part of their presurgical evaluation. As expected, for both RT and LT patients, long-term recognition of pictures presented under the effect of amobarbital was highly sensitive to the presence of a contralateral epileptic focus. However, contrary to what is generally reported, LT patients performed better than RT patients when their left (ipsilateral) hemisphere was anesthetized. In RT patients, although memory scores were lower after the left contralateral injection, the disparity in memory scores between the right and left injection was not as marked as in LT patients. These results are discussed in terms of the influence of type of processing required during the initial encoding on later recognition during IAP.

Site-specific effects of sympathectomy on the adrenergic control of lipolysis in hamster fat cells.

Regional variations in the response of adipose tissue to lipolytic stimuli have been suggested to be involved in the development of visceral adiposity-related morbidity and mortality. Moreover, studies in humans and in laboratory rodents such as hamsters have shown that the response of adipocytes to catecholamines depends on their anatomical origin. The aim of the present study was to investigate the relative involvement of the adrenal medulla and of the sympathetic nervous system on regional differences in the adrenergic control of lipolysis in isolated adipocytes from inguinal and epididymal adipose tissues. For this purpose, we carried out adrenal demedullation or chemical sympathectomy in hamsters. The results confirmed that epididymal adipocytes were significantly more responsive to to a beta-adrenergic stimulation than inguinal adipocytes (p < or = 0.05). This site specificity could originate at a step distal to receptors since tissues exhibited a similar number of binding sites for [125I]cyanopindolol. No significant regional differences were observed in the alpha2-adrenergic antilipolytic response, with the exception of the clonidine EC50. A 14-day sympathectomy significantly increased the beta-adrenergic lipolytic response only in inguinal adipocytes (p < or = 0.05), and increased the alpha2-adrenergic response only in epididymal adipocytes (p < or = 0.05). On the other hand, adrenal demedullation had no effect on both adrenergic pathways. These results suggest that the sympathetic tone of adipose tissues could be involved in the alpha2- and beta-adrenergic site-specific response in hamster fat cells. The 33% increase of the beta-response in inguinal fat cells and the 38% increase of the alpha2-response in epididymal fat cells also suggest that the sympathetic pathway favors the lipolytic activation of the epididymal adipose tissue.

GABAergic involvement in the acquisition of voluntary ethanol intake in laboratory rats.

Treatment with the GABAA agonist THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) or the GABAB agonist baclofen was shown to enhance the acquisition of voluntary ethanol consumption in laboratory rats. THIP administration resulted in an increased intake of absolute ethanol without an increase in total fluid intake. In contrast, baclofen administration, while increasing ethanol intake in a manner similar to that seen with THIP, also increased total fluid intake, indicating that its effects may not be specific to an interaction with ingested ethanol. The data obtained in the present study support the notion that GABAergic mechanisms, particularly those related to the GABAA receptor, may be involved in the acquisition of voluntary ethanol consumption in laboratory rats.