Detection of Glycosylated Markers From Cancer Stem Cells With ColoSTEM Dx Kit for Earlier Prediction of Colon Cancer Aggressiveness

Nowadays, colon cancer prognosis still difficult to predict, especially in the early stages. Recurrences remain elevated, even in the early stages after curative surgery. Carcidiag Biotechnologies has developed an immunohistochemistry (IHC) kit called ColoSTEM Dx, based on a MIX of biotinylated plant lectins that specifically detects colon cancer stem cells (CSCs) through glycan patterns that they specifically (over)express. A retrospective clinical study was carried out on tumor tissues from 208 non-chemotherapeutic-treated and 21 chemotherapeutic-treated patients with colon cancer, which were stained by IHC with the MIX. Clinical performances of the kit were determined, and prognostic and predictive values were evaluated. With 78.3% and 70.6% of diagnostic sensitivity and specificity respectively, our kit shows great clinical performances. Moreover, patient prognosis is significantly poorer when the MIX staining is “High” compared to “Low”, especially at 5-years of overall survival and for early stages. The ColoSTEM Dx kit allows an earlier and a more precise determination of patients’ outcome. Thus, it affords an innovating clinical tool for predicting tumor aggressiveness earlier and determining prognosis value regarding therapeutic response in colon cancer patients.

[Pneumonitis caused by hydrocarbon inhalation]

INTRODUCTION

Kerosene pneumonitis is rare. It most commonly occurs in children who have ingested a hydrocarbon by accident. In adults, pneumonitis caused by aspiration of incompletely vaporized kerosene may be seen in fire-eaters can cause pneumonitis.

CASE REPORTS

We report six cases of fire-eater's pneumonitis, from our region, due to hydrocarbon inhalation.

CONCLUSIONS

This inhalational pulmonary insult has classical clinical manifestations. The frequency of cases, particularly in tourist areas that host street festivals, is probably underestimated. Its tendency to spontaneously resolve questions the need for antibiotics and corticosteroids.

Expression of insulin-like growth factor-I in rat glioma cells is associated with change in both immunogenicity and apoptosis

Insulin-like growth factor I (IGF-I), has a role in cellular differentiation and is also expressed in neoplastic transformation of glioma cells. We recently demonstrated inhibition in expression of cellular IGF-I after transfection with vectors that incodes a segment of the human IGF-I RNA in antisense orientation. The transfected cells expressed increased levels of both MHC-I and B7 molecules. In this paper we show that IGF-I antisense transfected cells also become apoptotic. Moreover, the phenomenon of programmed cell death is related to the phenomenon that results in increased expression of MHC-I and B7 molecules. Co-transfection of rat glioma cells with the vector expressing IGF-I antisense RNA and with vectors encoding the expression of MHC-I and B7 antisense cDNA suppressed the expression of both of these molecules and was associated with a decrease in apoptosis.

Bacterial toxins modifying the actin cytoskeleton

Numerous bacterial toxins recognize the actin cytoskeleton as a target. The clostridial binary toxins (Iota and C2 families) ADP-ribosylate the actin monomers causing the dissociation of the actin filaments. The large clostridial toxins from Clostridium difficile, Clostridium sordellii and Clostridium novyi inactivate, by glucosylation, proteins from the Rho family that regulate actin polymerization. In contrast, the cytotoxic necrotic factor from Escherichia coli activates Rho by deamidation and increases the formation of actin filaments. The enterotoxin of Bacteroides fragilis is a protease specific for E-cadherin and it promotes the reorganization of the actin cytoskeleton. The bacterial toxins that modify the actin cytoskeleton induce various cell disfunctions including changes in cell barrier permeability and disruption of intercellular junctions.

Seizure-related opening of the blood-brain barrier produced by the anticholinesterase compound, soman: new ultrastructural observations

Previous macroscopic and light microscopic observations established that the organophosphate soman, an irreversible inhibitor of cholinesterases, produces seizure-related opening of the blood-brain barrier (BBB) to proteins. In Wistar rats, this BBB alteration was found to be reversible. This alteration was greatest during the first hour of seizures, and was topographically limited to sensitive areas such as the thalamus. In contrast, the hippocampus remained free of any vascular leakage. The present study is an attempt to elucidate, in rat thalamus, the subcellular mechanisms involved in soman-induced BBB alteration. A combination of three ultrastructural approaches was used: examination of ultra-thin sections, freeze-fracture, and post-embedding protein A-gold immunocytochemistry of the endogenous, normally exclusively blood-borne, albumin. Our findings show that soman-induced seizure activity produced no discernible structural change in the endothelial tight junctions, whereas it unambiguously increased the number of endothelial vesicles. Finally, immunolabelled albumin clearly crossed the endothelium, but was not systematically found inside the endothelial vesicles. Altogether, the present ultrastructural study confirms that soman can alter the integrity of the BBB, and demonstrates that the blood-to-brain passage of proteins does not mainly derive from the opening of tight junctions. Although transcytosis is clearly increased through the cerebral endothelium, there is little evidence that blood-borne proteins penetrate the brain in this way. The actual mechanisms of transport thus remain to be clarified.

Altered gap and tight junctions in human thyroid oncocytic tumors: a study of 8 cases by freeze-fracture

Human oncocytic tumors of the thyroid gland may be either adenomas or carcinomas. The morphology and the ultrastructure of these oncocytes are well-known. Numerous studies have demonstrated the role of gap and tight junctions in experimental and human carcinogenesis; however, the junctional complexes of the oncocytic tumors have never been studied. The aim of this study is to analyze gap and tight junctions in the oncocytic tumors of the thyroid. Because they are morphologically similar, whether benign or malignant, they offer an attractive model for studying the junctional complexes in both benign and malignant lesions. Eight oncocytic human thyroid tumors were collected and studied by freeze-fracture. Four of these cases were benign and four were malignant. Four cases of normal gland were also studied to represent the control group. Normal tight and gap junctions were described for the control group. No gap junctions could be found for the oncocytic tumors. Furthermore, alterations of the tight junctions were described; especially focal tights in the oncocytic adenomas and well organized and labyrinthic tight junctions in the oncocytic carcinomas. The lack of gap junction in the benign as well as in the malignant oncocytomas may suggest that the absence of gap junction is not sufficient for malignancy. The alterations of the tight junctions found in the oncocytic tumors of the thyroid are similar to those observed in poorly differentiated tissues or tumors, and may suggest a cellular regression rather than a tumorogenic factor.

Evidence that gonadotropin-releasing hormone stimulates gene expression and levels of active nitric oxide synthase type I in pituitary gonadotrophs, a process altered by desensitization and, indirectly, by gonadal steroids

To determine the site and mechanism of action of gonadal steroids on pituitary nitric oxide synthase type I (NOS I), present in both gonadotrophs and folliculo-stellate cells, the effects of castration and steroids were examined in male rats, in the presence of a GnRH antagonist (Antarelix). Western analysis showed a rapid and substantial increase with time, after orchidectomy, of NOS I protein, the concentration doubling in 24 h and reaching a maximal 4- to 5-fold increase after 3-7 days, followed by a progressive decline after 2 weeks. Testosterone or estradiol replacement, or administration of GnRH antagonist, totally abolished the effects of castration, demonstrating a mediation of the steroid effects via GnRH. In noncastrated rats, steroids and the GnRH antagonist also caused a reduction in the levels of NOS I (by 50-60%), consistent with inhibition of endogenous GnRH stimulation. In marked contrast, administration of a potent GnRH agonist (Triptorelin) to intact rats increased the levels of NOS I. A time-course study with a long-lasting formulation showed that rise in NOS I developed rapidly after a lag of approximately 5 h, with a 2-fold increase detectable after 8 h and a maximal 4.5-fold after 48 h. The level declined afterwards in a manner consistent with homologous desensitization that may occur in the continuous presence of GnRH; however, the profile was different and delayed compared with those of gonadotropin release. As observed for NOS I protein, NOS I messenger RNA concentration was increased by castration or GnRH agonist and reduced by steroids or GnRH antagonist. Taken together, these data demonstrate that steroids indirectly regulate NOS I messenger RNA and protein levels, through the hypothalamic modulation of GnRH, which represents the primary regulator of NOS I. No effect of steroids on NOS I was seen in the posterior lobe. NADPH-diaphorase histochemistry coupled to immuno-identification of the cells revealed that the treatments affecting the concentration of NOS I concomitantly altered the activity but exclusively in gonadotrophs and not in folliculo-stellate cells (which do not respond to GnRH), reinforcing the idea that GnRH played a major regulatory role. Expression in gonadotrophs of a GnRH-dependent NOS I and the ensuing production of nitric oxide represents a potentially novel signaling pathway for the neuropeptide in the anterior pituitary, consistent with the previously reported GnRH-induced cGMP production, the role of which remains to be evaluated.

Intestinal paracellular permeability during malnutrition in guinea pigs: effect of high dietary zinc

BACKGROUND

Zinc has been shown to have beneficial effects in vitro on epithelial barrier function, and in vivo to reduce intestinal permeability in malnourished children with diarrhoea.

AIMS

To determine whether malnutrition alters intestinal paracellular permeability, and whether zinc prevents such alterations.

METHODS

Guinea pigs were fed a normal protein diet (NP group), a low protein diet (LP group), or a low protein diet enriched with 1800 ppm zinc (LPZn group) for three weeks. Intestinal permeability was measured on jejunal segments mounted in Ussing chambers by measuring ionic conductance and mucosal to serosal fluxes of 14C-mannitol, 22Na, and horseradish peroxidase. Tight junction morphology was assessed on cryofracture replicas.

RESULTS

Mannitol and Na fluxes and ionic conductance increased in the LP group compared with the NP group but remained normal in the LPZn group. Accordingly, jejunal epithelia from the LP group, but not from the LPZn group, showed a small decrease in number of tight junctional strands compared with epithelia from the NP group. Neither malnutrition nor zinc treatment modified horseradish peroxidase fluxes.

CONCLUSIONS

Malnutrition is associated with increased intestinal paracellular permeability to small molecules, and pharmacological doses of zinc prevent such functional abnormality.

Establishment of hepatic cell polarity in the rat hepatoma-human fibroblast hybrid WIF-B9. A biphasic phenomenon going from a simple epithelial polarized phenotype to an hepatic polarized one

By immunofluorescence and freeze fracture methods, we have studied the establishment of hepatic cell polarity in WIF-B9 cells, a subclone of the WIF-B rat hepatoma-derived hybrid cell line. As previously shown (Ihrke et al. (1993) J. Cell Biol. 123, 1761–1775; Shanks et al. (1994) J. Cell Sci. 107, 813–825), these cells are a suitable model for in vitro studies of various hepatic functions, particularly polarity: in confluent cultures, the majority of cells form bile canaliculus-like structures; membrane domains are settled, according to plasma membrane protein localization similar to rat hepatocytes in situ. We here report that the establishment of WIF-B9 cell polarity is a slow progressive biphasic phenomenon. During the first days of culture, the majority of cells do not make bile canaliculus-like structures. However, they display a polarity similar to that of simple epithelial cells: apical membrane proteins and villin are found at the cell apex; basolateral ones, excluded from this area, are expressed in the remaining membrane area; the tight junction-associated protein ZO-1 and actin are concentrated at the boundary of these two poles, whereas E-cadherin is present at the lateral pole just under the apex. With time in culture, the number of cells expressing this simple epithelial polarized phenotype decreases progressively and, after 10–15 days, depending on the plating density, nearly all the cells express the typical hepatic polarized phenotype. The expression of these two phenotypes is mutually exclusive. Freeze-fracture replicas of both types of polarized cells show either macula occludens, fascia occludens (simple epithelial polarity) or zonula occludens (hepatic polarity), associated with gap junctions. In this last case, two or three continuous strands are generally present all around the bile canaliculus-like structures.

Compared effects of extracellular K+ ions and soman, a neurotoxic, on cerebral astrocyte morphology. An in vitro study

One of the roles of astrocytes in the maintenance of perineuronal ionic balance during intense neuronal activity occurring after injection of convulsant agents like soman. Soman is an irreversible cholinesterase inhibitor and induces brain damage with early swelling of astrocytic perivascular processes. Mature astrocytes are easily characterized on freeze-fracture replicas owing to the presence of regular geometric aggregates of intramembranous particles: the 'orthogonal arrays' (OAs). In primary cultures of astrocytes OA distribution is homogeneous throughout the plasma membrane. A present hypothesis (see review in Risau and Wolburg, 1990) considers that these OAs are associated with channels controlling potassium ion concentration in the cerebral parenchyma. We have investigated the effects of extracellular concentrations of K+ ions identical to those observed during neuronal activity on primary cultures of astrocytes and effects induced by soman. High concentrations of K+ ions (60 mM) as well as soman exerted direct effects on astrocytic plasma membranes: K+ ion influx within astrocytes induces a partial disaggregation of OAs and more acutely than soman. Neither K+ ions nor soman induce swelling of astrocytic end-feet.

The supra-ependymal innervation is not responsible for the repression of tight junctions in the rat cerebral ependyma

Classically, the contiguous epithelial cells show intercellular tight junctions (TJ) positioned as a continuous belt of cell-cell contacts at the boundary of apical and basolateral plasma membranes. Among the epithelia, the "typical" cerebral ependyma is very peculiar due to the absence of TJ, in contrast to the ependyma of the circumventricular organs (e.g. choroid plexus and the subcommissural organ) which shows well differentiated TJ. Since the "typical" ependyma is covered in the rat with a plexus of intraventricular nervous fibres not present at the surface of the circumventricular organs, we hypothesized local repression of TJ by molecules (serotonin, GABA, etc.) released by the supra-ependymal varicosities. Neither the denervation of the "typical" ependyma nor the ex vivo activation of protein kinase C (which increases the transepithelial resistance as it has been reported in other epithelia) produced junctional fibrils as shown by freeze-fracture. As the protein ZO-1 was not detectable in the "typical" ependyma by immunocytochemistry, there is probably repression of the genes responsible for TJ biosynthesis by unidentified endogenous factors.

Tumour necrosis factor-alpha induces morphological and functional alterations of intestinal HT29 cl.19A cell monolayers

TNF-alpha is a widely distributed proinflammatory cytokine, involved in many disease states. Although it has widely distributed effects, a precise mechanism of action has never been described, in particular at the epithelial level. Morpho-functional changes of the intestinal epithelial monolayer HT29 cl.19A exposed to TNF-alpha were therefore assessed, using electron microscopy (including freeze-fracture replica analysis), as well as measurement of mannitol, Na+ and horseradish peroxidase fluxes across intestinal HT29 cl.19A cell monolayers using Ussing chambers. TNF-alpha receptors were induced on HT29 cl.19A cells by a small non-toxic dose of IFN-gamma (5 U/ml). After 4 h of the combined presence of TNF-alpha (10 ng/ml) and IFN-gamma (5 U/ml), the tight junction structure was altered as shown by a significant decrease in the average strand number measured in the apico-basal direction (5.50 +/- 2.70 vs 3.73 +/- 1.39 in control and treated cells respectively, P < 0.0001) and by a significant decrease in junctional depth (0.27 +/- 0.14 and 0.17 +/- 0.10 microns in control and treated cells respectively, P < 0.0001). These results are in agreement with a decrease in number of 'kiss' sites between contiguous membranes of TNF-alpha treated cells observed in ultrathin sections.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of nitric oxide in the neuropathology in soman intoxication

Intoxication with organophosphorus (0P) anticholinesterase agents such as soman triggers irreversible lesions in some cerebral areas. Administration of soman at the LD 50 leads to an increased activity of NADPH-diaphorase (= NO-synthase) in the cerebral endothelial cells from the 6th hour after poisoning. This activity culminates after 24 h, whereas variations in this enzymatic activity are not easily detectable in NADPH-diaphorase positive neurons. Since soman triggers astrocytic oedema leading to a possible decrease in the local cerebral blood flow, it is likely that the induction of endothelial NO-synthase exerts an antagonistic effect, since NO is a vasodilator.

Effects of soman on cerebral astrocyte plasma membranes: a freeze-fracture study

Astrocytes are identifiable on freeze-fracture by regular geometric aggregates of uniform intramembranous particles (IMP), the 'orthogonal arrays' (OA). These OAs are considered to be potassium channels that maintain the ionic balance around neurons. After subcutaneous administration of a single near LD50-dose of soman in rats, neurotoxic epileptogenic irreversible cholinesterase inhibitor, replicas showed a significant decrease in OA density in the convulsed animals. This dissociation by soman confirms that OA are a particularly labile membranes specialization. Frequent clumping of IMP and numerous cleavage planes were observed; this could be the result of an interaction between the liposoluble poison and membrane phospholipid fluidity.

Contribution of peripheral macrophages and microglia to the cellular reaction after mechanical or neurotoxin-induced lesions of the rat brain

Lesions of the central nervous system result in invasion of peripheral phagocytes and/or in situ activation and proliferation of microglia, depending on the direct or indirect nature of the injury. Neurotoxins which are widely used to induce neurodegeneration have been reported to elicit a pure microglial reaction when administered intraventricularly. However, the mechanical lesion at the injection site, although remote from the lesioned area, could give access to blood-derived cells. Therefore, this study compares the phagocytic reaction occurring after a traumatic lesion of the brain causing a breakdown of the blood-brain barrier (BBB), or after degeneration of the inferior olivary neurons induced by intraperitoneal administration of 3-acetylpyridine, a process that respects the integrity of the BBB as suggested by the results of intravascular injection of Evans blue. The identification of the macrophages at the lesion site used specific binding of the B4 isolectin from Griffonia simplicifolia, preloading of the peripheral monocytes/macrophages with trypan blue, and characteristic morphological features. In traumatically lesioned rats, the lectin-labeled macrophages were mainly large rounded peripheral cells recruited 1-3 days postlesion, whereas in chemically lesioned rats, the cellular reaction appeared 24-36 h postinjection and peaked between 3 and 12 days before undergoing a slow decline. Lectin binding and morphological characteristics indicated that these small cells were reactive microglia. These results confirm that a brain injury leaving the BBB intact involves essentially the recruitment and/or the proliferation of microglia.

Variation in the expression of c-fos after intoxication by soman. Comparative study using in situ hybridization and immunohistochemistry

A massive and transitory increase in c-fos mRNA and Fos protein occurred in rats intoxicated by a single dose of soman (organophosphate compound and irreversible cholinesterase inhibitor) only in animals that had seizures. Comparison of immunohistochemistry that localizes Fos protein and of in situ hybridization that localizes its mRNA showed that there was an early and explosive expression of mRNA in many cerebral regions followed by transitory immunoreactivity in only some regions (piriform cortex, entorhinal area, hippocampus). The levels of mRNA and c-fos-like immunoreactivity decreased slowly and returned to basal level 24 h after soman administration.

Efficiency of liposomal ATP in cerebral ischemia: bioavailability features

This study was performed to elucidate the mechanism by which adenosine triphosphate (ATP) encapsulated into liposomes was able to protect against experimental brain ischemia in the rat. After intracarotidal administration of liposomally entrapped ATP, the ATP blood level increased dramatically whereas no change was observed after administration of free ATP. This suggested that liposomes may protect ATP from its degradation by endothelial ectonucleotidases. On the other hand, it was observed that after administration of liposomally entrapped carboxyfluorescein (CF) to ischemic rats, the distribution of the brain fluorescence under the form of numerous punctiform structures was completely different from the diffuse fluorescence obtained with free CF injections. These data suggest that under certain hypoxic conditions the blood-brain barrier is open allowing the liposomes to reach the cerebral parenchyma. The mechanism of brain uptake is, however, still unclear: endothelial tight junctions opening or endothelial transcytosis.

Initial process of diffusion of small molecules from blood vessels to the meninges in the young rat

Pathways taken by peripherally administered small molecules when entering the brain were investigated in 6-day-old rats by radioautography and fluorescence microscopy after intravenous administration and rapid freezing. L-[U-14C]Phenylalanine, [U-14C]sucrose and sodium fluorescein reached the brain within less than 5 seconds. These blood-borne molecules were found in the subarachnoid cisterns and the superficial parenchyma. These results suggest a special permeability of the arachnoid layer and/or the pial vessels. Phenylalanine alone reached the deep parenchyma because of the existence of a specific endothelial carrier.

Permeability of the normal rat brain, spinal cord and dorsal root ganglia microcirculations to immunoglobulins G

The distribution of blood-borne immunoglobulins G (IgG) was studied in the cerebral cortex, pineal gland, spinal cord and dorsal root ganglia of normal Lewis rats using the detection of autologous anti-horseradish peroxidase (HRP) antibodies. This detection was performed by means of light and electron microscopy. This study demonstrated that, in the cerebral cortex and the spinal cord microcirculations, endothelial cells are a restrictive barrier against IgG while IgG are able to diffuse into the perivascular parenchyma of the pineal gland and spinal ganglia.

Biodistribution of an anti-interleukin 2 receptor monoclonal antibody in rat recipients of a heart allograft, and its use as a rejection marker in gamma scintigraphy

Anti-interleukin-2 receptor monoclonal antibodies have been shown to prevent allograft rejection. This paper reports on the biodistribution of a mouse MoAb directed at the 55 Kd alpha chain of rat interleukin-2 receptor (IL2-R) during allograft rejection. Only a low percentage (approximately 1%) of intact 125I-labeled MoAb was detected in the rejected graft, and irrelevant control IgG1 was found at a similar level. This suggests that most of the injected intact MoAb bound to graft tissue via its monomorphic Fc segment. In contrast, OX39 F(ab')2 fragments showed a preferential localization in the rejected allograft and did not bind to the LEW-to-LEW syngeneic heart graft. Irrelevant F(ab')2 did not concentrate in the allogeneic graft. Accordingly, F(ab')2 fragments from OX39 or irrelevant MoAb were used for gamma-scintigraphy on allograft recipients together with biodistribution studies. Results show that scintigraphy was able to detect allograft accumulation of 131I OX39 F(ab')2, whereas no imaging was obtained when OX39 F(ab')2 was used in the syngeneic combination or when irrelevant 131-IgG1 F(ab')2 was given to allograft recipients. This method, applied to the clinical situation, could be of interest for detection of early graft rejection episodes by immunoscintigraphy using reagents specific for activation determinants on lymphocyte membranes, such as anti-interleukin-2 receptor MoAb.

Interspecific variations of cerebral endothelial cholinesterases in rodents and carnivores

The cholinesterase equipment of cerebral microvessels was studied in some rodents and carnivores using the Koelle-Friedenwald histochemical method with 3 artificial substrates and specific inhibitors for butyrylcholinesterase or acetylcholinesterase. Our observations reveal a great heterogeneity in cholinesterase types and their distribution in each of the different species studied. Only in the rat, butyrylcholinesterase appears to be a marker for the microvessels provided with a blood-brain barrier.

Localization of acetylcholinesterase activity at synapses of the rat striatum during the stages of recovery after inhibition in vivo

A pharmacohistological method was used to study the ultrastructural localization of acetylcholinesterase in the rat striatum. Five hours after administration of an organophosphorous inhibitor (paraoxon), high activities of this enzyme were selectively found in some neurons and at numerous axo-spinous synapses of the asymmetrical type. The cholinergic nature of these synapses appeared unlikely.

Histamine-induced constriction and dilatation of rabbit middle cerebral arteries in vitro: role of the endothelium

We studied the effects of histamine on perfused rabbit middle cerebral arteries in vitro. Intact and endothelium-denuded preparations were compared. Histamine caused concentration-dependent constrictions in intact vessels which were competitively inhibited by an H1 receptor antagonist. This constriction was potentiated by either H2-receptor blockade or endothelium denudation. The greatest potentiation was observed with intraluminal as opposed to extraluminal administration. The H1 receptor agonist pyridylethylamine induced similar concentration-dependent constriction in intact and denuded preparations. After preconstriction, histamine, in the presence of an H1 receptor antagonist, dilated intact vessels to a maximum of 45.1%, and endothelium-denuded vessels to a maximum of 22% (p less than 0.02). We conclude that rabbit middle cerebral arteries possess H1 constrictory and H2 dilatory receptors, and that many of the H2 dilatory receptors are situated on the endothelial cells.

Formation and maturation of axo-glandular synapses and concomitant changes in the target cells of the rat subcommissural organ

Synapse formation and maturation in the subcommissural organ (SCO) of Wistar rats were studied from birth to the end of the first month. Modifications of the secretory ependyma were analyzed over the same period. On the 1st postnatal day, the large varicosities in contact with the SCO ependymocytes appeared immature (absence or low density of vesicular population, no synaptic membrane differentiation). The synaptic contacts were formed from the 3rd postnatal day, near the glandular cell nuclei (0.1 micron distance); progressively, the content of the axonal boutons and the pre- and post-synaptic specializations became similar to those of adults. From the 21st day on, the axo-glandular innervation was considered analogous to that in the adult. Using immunocytochemistry, it was found that the increase in the serotonin-immunoreactive fiber density in the whole organ was time-dependent. Light and electron microscopy demonstrated changes in the morphology of SCO ependymocytes during the first postnatal weeks, notably in the endoplasmic reticulum and content ot apical protrusions. On postnatal day 14, two types of ependymal cells, neonatal-like and adult-like, coexisted. The evolution of SCO ependymocytes coincided with the progressive onset and maturation of axo-glandular innervation taking place after birth.

Long-term effects of superior cervical ganglionectomy on cortical blood flow of non-anesthetized rabbits in resting and hypertensive conditions

The long-term effects of sympathectomy on cerebral cortical blood flow (CBF) were studied in the conscious rabbit. The quantitative, repeated measurements of blood flow were made by determination of helium clearance by mass spectrometry and were obtained simultaneously with measurements of local tissue pO2 and pCO2. Eight to 10 weeks after unilateral sympathectomy, resting blood flow in the homolateral cortex was decreased by a mean of 17% compared to the heterolateral cortex. In two animals in which blood flow was recorded both before and after the sympathectomy, the same phenomenon was observed from 8 to 30 days after the operation. The response to i.v. infusion of noradrenaline was identical in both hemispheres: doses inducing a 40% rise in blood pressure did not significantly modify CBF. The responses to angiotensin II-induced hypertension were also identical. Histochemical verifications demonstrated the effectiveness of the denervation in the pial arteries and the intraparenchymal arteries in the region studied. Thus the decrease in CBF induced by chronic sympathectomy cannot be attributed to the development of hypersensitivity to catecholamines. This decrease remained stable whatever the value of resting flow and was maintained under anesthesia. It is concluded that, as in the peripheral circulation, chronic sympathectomy affects the equilibrium of the vascular smooth muscle fibers, but that circulating amines play no compensatory role in the cerebral circulation because of the blood-brain barrier.

Electron-microscopic immunohistochemical study of the localization of immunoglobulin G in the choroid plexus of the rat

The localization of autologous antiperoxidase immunoglobulin G (IgG) was studied in the choroid plexus of Lewis rats immunized against horseradish peroxidase (HRP). This experiment was performed to study the permeability of the choroid plexus to intravascular IgG. It was shown that autologous IgG was present in the extravascular spaces. The transendothelial transfer appeared to occur mainly via the fenestrations and some interendothelial junctions. No transfer of IgG at the level of epithelial cells toward the cerebrospinal fluid was demonstrated. Interstitial spaces in contact with the connective-tissue cells of the choroid stroma were strongly labeled. The significance of these spaces remains hypothetical and raises the question of the fate of IgG from the interstitial space.

The ependymal secretion of the fetal and adult rat subcommissural organ. morphological aspects linked to the synthesis, storage and release of the secretory products

Different localizations of secretory material are noted in adult and fetal subcommissural organ (SCO) in light microscopy. At the electron microscope level, the secretory ependymocytes reveal frequent associations among mitochondria and ribosomes of the endoplasmic reticulum (ER). In the SCO ependymocytes of the adult rat, the relationship between mitochondria and ribosomes of the ER is observed in the subgolgian zone, the ER cisternal profiles are smooth except where they face the mitochondria. Here, a constant interval of 40-45 nm separates the ribosome-coated ER membrane from the external membrane of the mitochondria. This association evidences a functional cooperation between mitochondria and ER, at least in some phases of the synthesis of the organ's gliosecretory material. By contrast, in the fetus (17-21 fetal day), the synthetic apparatus displays an entirely granular ER. The secretory products are stored as flocculent material which fills the ER cisternae. In the apical zone of the ependymocytes, as the membrane of the dense secretory granules fuses with the apical plasmalemma, the granules release their contents into the ventricular cavity. A possible link between the releasing process and the coated vesicles is discussed.

Evidence for the effectiveness of the blood--CSF barrier in the fetal rat choroid plexus. A freeze-fracture and peroxidase diffusion study

The blood--cerebrospinal fluid (CSF) barrier in the choroid plexus is principally constituted of apical junctional complexes between epithelial cells. The effectiveness of this barrier was studied during the fetal development in the rat. Choroid plexuses from fetuses (14th and 18th embryonic day) and newborn (1 and 6 day old) rats were examined after intravascular administration of a proteic tracer (horseradish peroxidase) and investigated by freeze-fracture. From the 14th day of fetal life, apical junctions were seen to constitute a barrier that prevents the passage of peroxidase from blood to CSF; the tight junctions were morphologically similar to those of the mature animals; the junctional fibrils appeared continuous on complementary replicas. These data suggest that, from the 14th day of fetal development, the blood--CSF barrier is both morphologically and physiologically mature.

[Immunocytochemical study of serotoninergic supraependymal fibres in the rat. A Golgi-like study (author's transl)]

The supraependymal serotoninergic axons are identified in the Rat by immunocytochemistry. A dense plexus of fibres presenting various calibers is visualized over all the ventricular walls when tangential sections are used. By place, in the lateral ventricles, fibres emerging from an ependymal hollowing are often clustered in small groups. As soon as they penetrate the ventricles, they ramify profusely in various branches.

[Electrocorticograms and the histochemical effects in the rat accompanying the reactivation of cholinesterases after the effects of an organophosphorus inhibitor]

The administration of paraoxon, an organophosphate inhibitor of cholinesterases, elicits theta rhythms, fast rhythms and paroxystical alterations on the electrocorticogram of the Rat. The disappearance of these abnormalities of the cortical activity after administration of aromatic oximes seems to be in good correlation with the restoration of cerebral cholinesterase activity revealed by histochemical method.

The tight junctions of rabbit choroid plexus and ciliary body epithelia. A comparative study using the double replica freeze-fracture technique

The spatial arrangement of tight junctions in choroid plexus and ciliary body rabbit epithelia has been determined by studying freeze-fracture complementary replicas. In the choroid plexus epithelium, the interruptions of the junctional P-face fibrils were measured to be 14% in their total length. In the ciliary body epithelium, where the fibrils were found to be more fragmented than in the choroid plexus, the P-face fibril interruption accounted for 12% of the total length of the zonulae occludentes sealing the non-pigmented cells and 30% in the focal linear tight junctions connecting the non-pigmented cells at their apices. In both epithelia, the interruptions of the ridges are precisely complemented by particles or short bars of similar length found in the E-face furrows. Consequently, it is possible to conclude that the junctional fibrils are continuous in these two epithelia. For the zonulae occludentes, this continuity appears to be inconsistent with the 'leaky' properties of these epithelia shown by some physiological investigations.

Evidence for a multiple innervation of subcommissural ependymocytes in the rat

Glandular ependymocytes of the rat subcommissural organ (SCO) receive a multiple innervation: a serotonergic afference identified by radioautography and at least one other input of a hitherto unknown transmitter content. Both types of terminals make well differentiated axo-glandular synapses with SCO-ependymocytes, but display different morphological characteristics. Serotonergic terminals being considered as inhibitory, it is suggested that the other type of terminal is excitatory.

Penetration of oximes across the blood-brain barrier. A histochemical study of the cerebral cholinesterases reactivation

The comparison of the effects of 4 oximes upon the cerebral cholinesterases reactivation after intoxication with paraoxon shows that the best results are obtained with toxogonine and 1574 [(carbaldoxime-4 pyridinium)-1(methyl-1 imidazolium-3)-3 propane]. The reactivation power of this latter compound seems due to the ease with which it can pass through the blood-brain barrier.

Fine structure of tight junctions between rat choroidal cells after osmotic opening induced by urea and sucrose

After ventriculo-cisternal perfusion of hypertonic urea or sucrose, both the choroid plexus permeability to horseradish peroxidase and the structure of tight junctions between choroidal cells are modified. Intercellular spaces are swollen, continuous ridges are fragmented and intrajunctional spaces are invested by many membranous particles. These morphological alterations appear to be reversible. These ultrastructural data are related to an osmotic maladjustment induced by the introduction of hypertonic solutions into the cerebro-spinal fluid.

[Supra-ependymal "giant"" nerve terminals in rodent brains]

In the lateral ventricles and third ventricle of the Rat and Mouse brain a dense net of supraependymal amyelinic varicose axons is obvious. Moreover, orginating from this was found small quantities of "giant" supra-ependymal nerve endings evoking sometimes the aspect of sensory terminals. These two types of supra-ependymal structures seem to contain 5-hydroxytryptamine.