Cannabis-Associated Psychotic-like Experiences Are Mediated by Developmental Changes in the Parahippocampal Gyrus

OBJECTIVE

Cannabis consumption during adolescence has been reported as a risk factor for psychotic-like experiences (PLEs) and schizophrenia. However, brain developmental processes associated with cannabis-related PLEs are still poorly described.

METHOD

A total of 706 adolescents from the general population who were recruited by the IMAGEN consortium had structural magnetic resonance imaging scans at both 14 and 19 years of age. We used deformation-based morphometry to map voxelwise brain changes between the two time points, using the pairwise algorithm in SPM12b. We used an a priori region-of-interest approach focusing on the hippocampus/parahippocampus to perform voxelwise linear regressions. Lifetime cannabis consumption was assessed using the European School Survey Project on Alcohol and other Drugs (ESPAD), and PLEs were assessed with the Comprehensive Assessment Psychotic-like experiences (CAPE) tool. We first tested whether hippocampus/parahippocampus development was associated with PLEs. Then we formulated and tested an a priori simple mediation model in which uncus development mediates the association between lifetime cannabis consumption and PLEs.

RESULTS

We found that PLEs were associated with reduced expansion within a specific region of the right hippocampus/parahippocampus formation, the uncus (p = .002 at the cluster level, p = .018 at the peak level). The partial simple mediation model revealed a significant total effect from lifetime cannabis consumption to PLEs (b = 0.069, 95% CI = 0.04-0.1, p =2 × 10^-16), as well as a small yet significant, indirect effect of right uncus development (0.004; 95% CI = 0.0004-0.01, p = .026).

CONCLUSION

We show here that the uncus development is involved in the cerebral basis of PLEs in a population-based sample of healthy adolescents.

The symbiotic complex of Dendroctonus simplex: implications in the beetle attack and its life cycle

The eastern larch beetle (Dendroctonus simplex Le Conte) is recognized as a serious destructive forest pest in the upper part of North America. Under epidemic conditions, this beetle can attack healthy trees, causing severe damages to larch stands. Dendroctonus species are considered as holobionts, as they engage in multipartite interactions with microorganisms, such as bacteria, filamentous fungi, and yeasts, which are implicated in physiological processes of the insect, such as nutrition. They also play a key role in the beetle's attack, as they are responsible for the detoxification of the subcortical environment and weaken the tree's defense mechanisms. The eastern larch beetle is associated with bacteria and fungi, but their implication in the success of the beetle remains unknown. Here, we investigated the bacterial and fungal microbiota of this beetle pest throughout its ontogeny (pioneer adults, larvae and pupae) by high-throughput sequencing. A successional microbial assemblage was identified throughout the beetle developmental stages, reflecting the beetle's requirements. These results indicate that a symbiotic association between the eastern larch beetle and some of these microorganisms takes place and that this D. simplex symbiotic complex is helping the insect to colonize its host tree and survive the conditions encountered.

Neural Correlates of Failed Inhibitory Control as an Early Marker of Disordered Eating in Adolescents

BACKGROUND

Binge eating and other forms of disordered eating behavior (DEB) are associated with failed inhibitory control. This study investigated the neural correlates of failed inhibitory control as a potential biomarker for DEB.

METHODS

The study used prospective longitudinal data from the European IMAGEN study adolescent cohort. Participants completed baseline assessments (questionnaires and a brain scan [functional magnetic resonance imaging]) at 14 years of age and a follow-up assessment (questionnaires) at 16 years of age. Self-reported binge eating and/or purging were used to indicate presence of DEB. Neural correlates of failed inhibition were assessed using the stop signal task. Participants were categorized as healthy control subjects (reported no DEB at both time points), maintainers (reported DEB at both time points), recoverers (reported DEB at baseline only), and developers (reported DEB at follow-up only). Forty-three individuals per group with complete scanning data were matched on gender, age, puberty, and intelligence (N = 172).

RESULTS

At baseline, despite similar task performance, incorrectly responding to stop signals (failed inhibitory control) was associated with greater recruitment of the medial prefrontal cortex and anterior cingulate cortex in the developers compared with healthy control subjects and recoverers.

CONCLUSIONS

Greater recruitment of the medial prefrontal and anterior cingulate regions during failed inhibition accords with abnormal evaluation of errors contributing to DEB development. As this precedes symptom onset and is evident despite normal task performance, neural responses during failed inhibition may be a useful biomarker of vulnerability for DEB. This study highlights the potential value of prospective neuroimaging studies for identifying markers of illness before the emergence of behavior changes.

Analysis of the phthiocerol dimycocerosate locus of Mycobacterium tuberculosis. Evidence that this lipid is involved in the cell wall permeability barrier

Among the few characterized genes that have products involved in the pathogenicity of Mycobacterium tuberculosis, the etiological agent of tuberculosis, are those of the phthiocerol dimycocerosate (DIM) locus. Genes involved in biosynthesis of these compounds are grouped on a 50-kilobase fragment of the chromosome containing 13 genes. Analysis of mRNA produced from this 50-kilobase fragment in the wild type strain showed that this region is subdivided into three transcriptional units. Biochemical characterization of five mutants with transposon insertions in this region demonstrated that (i) the complete DIM molecules are synthesized in the cytoplasm of M. tuberculosis before being translocated into the cell wall; (ii) the genes fadD26 and fadD28 are directly involved in their biosynthesis; and (iii) both the drrC and mmpL7 genes are necessary for the proper localization of DIMs. Insertional mutants unable to synthesize or translocate DIMs exhibit higher cell wall permeability and are more sensitive to detergent than the wild type strain, indicating for the first time that, in addition to being important virulence factors, extractable lipids of M. tuberculosis play a role in the cell envelope architecture and permeability. This function may represent one of the molecular mechanisms by which DIMs are involved in the virulence of M. tuberculosis.

PCR-ribotyping of Xenorhabdus and Photorhabdus isolates from the Caribbean region in relation to the taxonomy and geographic distribution of their nematode hosts

The genetic diversity of symbiotic Xenorhabdus and Photorhabdus bacteria associated with entomopathogenic nematodes was examined by a restriction fragment length polymorphism analysis of PCR-amplified 16S rRNA genes (rDNAs). A total of 117 strains were studied, most of which were isolated from the Caribbean basin after an exhaustive soil sampling. The collection consisted of 77 isolates recovered from entomopathogenic nematodes in 14 Caribbean islands and of 40 reference strains belonging to Xenorhabdus and Photorhabdus spp. collected at various localities worldwide. Thirty distinctive 16S rDNA genotypes were identified, and cluster analysis was used to distinguish the genus Xenorhabdus from the genus Photorhabdus. The genus Xenorhabdus appears more diverse than the genus Photorhabdus, and for both genera the bacterial genotype diversity is in congruence with the host-nematode taxonomy. The occurrence of symbiotic bacterial genotypes was related to the ecological distribution of host nematodes.

Phagosomal pH determination by dual fluorescence flow cytometry

Several methods have been developed to measure the pH of phagosomes, using fluorescein derivatives as reporter of pH, and spectrofluorimetry, fluorescence microscopy, or flow cytometry as quantification technique. All have major disadvantages, including either a slow or inaccurate response. In the present study, pH determination was achieved on J774-cell phagosomes containing dual-labeled zymozan particles using dual fluorescence flow cytometry with an argonion laser excitation wavelength at 488 nm. This allowed zymozan-containing macrophages to be distinguished from other cells and their fluorescence to be measured rapidly. The use of a new probe, namely Oregon Green 488 which has a pKa lower than carboxyfluorescein with the same maximum excitation and emission wavelengths, allowed investigation of pH value below 5. The dual labeling with Oregon Green 488 and carboxytetramethylrhodamine as pH-sensitive and pH-insensitive probes, respectively, overcame the absence of an isobestic point in the Oregon Green 488 spectrum. The phagosomal pH was determined using a calibration curve of phagosomal pH established by adding ionophores in phagocyte suspension and measuring the fluorescence intensity ratio (535 nm/585 nm) for different pHs. A phagosomal pH of 4.5 +/- 0.1 can be accurately determined. This method permits pH measurements down to 4, even in the presence of nonengulfed reporter particles.

Mycobacterium smegmatis phosphoinositols-glyceroarabinomannans. Structure and localization of alkali-labile and alkali-stable phosphoinositides

Lipoarabinomannans from fast growing Mycobacterium sp., namely AraLAMs, stimulate the early events of macrophage activation. The immunological activities of all of these AraLAMs drastically decrease with the loss of the mild alkali groups, which were believed to be restricted to the fatty acid residues from the phosphatidyl-myo-inositol anchor. This report reveals the presence and the structure of mild alkali-labile phosphoinositide units linked via the phosphate to the C-5 of the beta-D-Araf in the AraLAMs of Mycobacterium smegmatis, a fast growing mycobacterial species. Their structure was unambiguously established with a strategy based on both one-dimensional 31P and two-dimensional 1H-31P heteronuclear multiple quantum correlation spectroscopy (HMQC) and HMQC-homonuclear Hartmann-Hahn spectroscopy NMR experiments applied to native AraLAMs and to AraLAMs treated in mild alkali conditions. Next to these alkali-labile phosphoinositides estimated at three per molecule, two other mild alkali-stable phosphoinositide units were identified: the expected (myo-inositol-1)-phosphate-(3-glycerol) unit typifying the well known glycosylphosphatidylinositol anchor of the mannan core and, more surprisingly, one (myo-inositol-1)-phosphate-(5-beta-D-Araf) unit having the same structure as the alkali-labile ones. Moreover, these four phosphoinositide units were found capping the arabinan side chains. Thus, their different behavior toward mild alkaline hydrolysis was explained according to their accessibility to the alkali reagent. This novel class of LAMs, namely phosphoinositols-glyceroarabinomannans (PI-GAMs), are characterized by their phosphoinositide units but also by the absence of fatty acid residues. These PI-GAMs were found to elicit the secretion of tumor necrosis factor-alpha, suggesting that phosphoinositides are the major PI-GAM epitope involved in this process.

High-pH anion-exchange chromatographic analysis of phosphorylated compounds: application to isolation and characterization of nonpeptide mycobacterial antigens

A rapid and sensitive high-pH anion-exchange chromatography (HPAEC) method for the separation and quantification of phosphorylated antigens in mycobacterial extracts has been developed. This method provides the separation of mono-, di-, or triphosphonucleotides and of various other phosphorylated molecules. Dual detection by conductimetry and UV absorption downstream of a chemical suppressor constitute nondegradative and highly sensitive tools for the physical detection and the quantification of phosphorylated compounds in biological samples. The lower limit of accurate quantification is around 1 nmol per sample. This method was used for the separation of several phosphorylated antigens activating human gamma delta T lymphocytes from semipurified mycobacterial fractions. Their quantification revealed that the minimal concentration activating a gamma delta T cell clone is between 1 and 5 nM. This approach can be used for more general preparative purposes with samples where minute amounts of biologically active phosphoanions are analyzed.

A novel nucleotide-containing antigen for human blood gamma delta T lymphocytes

The stimulation of human gamma delta T cells by mycobacteria occurs through recognition of four distinct nonpeptide phosphorylated antigens termed TUBag1-4. Among these latter, TUBag4 has already been biochemically characterized as a gamma-X derivative of 5'-deoxythymidine triphosphate (Constant, P., Davodeau, F., Peyrat, M. A., Poquet, Y., Puzo, G., Bonneville, M. and Fournié, J.-J., Science 1994. 264: 267). However, despite chemical synthesis of weakly stimulatory nucleotide-containing analogs, these mycobacterial compounds remained the sole nucleotide-containing antigens actually isolated from natural sources. Here, we present the complete isolation of the TUBag3 antigen from Mycobacterium fortuitum and demonstrate that this nonpeptide molecule contains a 5'-UTP nucleotide moiety. On selected V gamma 9/V delta 2 clones, T cell responses can be triggered with nanomolar concentrations of TUBag3. Like crude mycobacterial extracts, this purified nucleotide conjugate elicits a strong polyclonal response of gamma delta PBL from healthy donors. Furthermore, we present evidence that this compound is distinct from the recently synthesized gamma-isopentenyl 5'-UTP, a nucleotide conjugate of isopentenyl pyrophosphate that was found to be stimulatory for human gamma delta T cells (Tanaka, Y., Morita, C.T., Tanaka, Y., Nieves, E., Brenner, M. B. and Bloom, B. R., Nature 1995. 375: 155). Since it appears that both mycobacterial nucleotide antigens are molecules structurally related to peculiar precursors of nucleic acid synthesis, we propose that TUBag-reactive T cells might be specifically devoted to surveillance of proliferating cells.

Plasmodium falciparum stimuli for human gammadelta T cells are related to phosphorylated antigens of mycobacteria

The presence in Plasmodium falciparum of a mitogenic factor for the major human blood gammadelta T-cell subset has been known for years. These gammadelta T cells bearing T-cell receptor Vgamma9 and Vdelta2 variable regions also respond to Mycobacterium tuberculosis, through recognition of several phosphorylated nonpeptidic antigens. In this study, we undertook a better characterization of the malarial stimulus and show that the polygonal activation of Vgamma9/Vdelta2 gammadelta T cells by P. falciparum schizonts is also and exclusively attributable to two phosphorylated malarial compounds. The finding of such stimuli in eukaryotic cells evidence an antigenic link between intracellular parasites as different as Plasmodium and Mycobacterium species. Hence, phosphorylated antigens could be involved in a common pattern of transdisease T-cell responses against various human pathogens.

The antituberculous Mycobacterium bovis BCG vaccine is an attenuated mycobacterial producer of phosphorylated nonpeptidic antigens for human gamma delta T cells

The mycobacterial antigens stimulating human gamma delta T lymphocytes (R. L. Modlin, C. Permitz, F. M. Hofman, V. Torigian, K. Uemura, T. H. Rea, B. R. Bloom, and M. B. Brenner, Nature (London) 339:544-548, 1989; D. H. Raulet, Annu. Rev. Immunol. 7:175-207, 1989) have been characterized recently in Mycobacterium tuberculosis H37Rv as a group of four structurally related nucleotidic or phosphorylated molecules, termed TUBag1 to -4 (tuberculous antigens 1 to 4) (P. Constant, F. Davodeau, M. A. Peyrat, Y. Poquet, G. Puzo, M. Bonneville, and J. J. Fournie, Science 264:267-270, 1994). Here, we analyzed their distribution in different mycobacterial species of the M. tuberculosis group, with special emphasis on the human vaccine Mycobacterium bovis BCG. We show that the same four TUBag1 to -4 molecules are shared by these mycobacteria. Quantitative comparison reveals, however, that while the pathogen M. bovis and M. tuberculosis species produce rather high amounts of TUBag, all of the BCG strains have a surprisingly reduced production of TUBag. These observations suggest that among tuberculous mycobacteria, the bacterial TUBag load could, to some extent, constitute an immunological determinant of mycobacterial virulence for humans.

Early activation of human V gamma 9V delta 2 T cell broad cytotoxicity and TNF production by nonpeptidic mycobacterial ligands

Human V gamma 9V delta 2 T cells were shown recently to respond to nonpeptidic phosphorylated molecules of mycobacterial origin (previously referred to as TUBag). To investigate the early events of V gamma 9V delta 2 T cell activation, we have analyzed induction of cytotoxicity and TNF production of T cell clones by these molecules. We showed that within minutes after exposure, TUBag induced cytotoxicity of V gamma 9V delta 2 CTL (but not of CTL expressing other TCR V gamma/V delta or V alpha/V beta regions) against a broad set of target cells, including effector cells themselves. Induction of V gamma 9V delta 2 cytotoxicity by TUBag was blocked by anti-TCR mAbs and was abrogated after dephosphorylation of TUBag. Similarly, TUBag, but not dephosphorylated TUBag, induced massive TNF production by V gamma 9V delta 2 T cell clones only, which already was significant 20 min after exposure. Of note, only basal amounts of TNF were produced when cells were maintained in suspension in the presence of TUBag, indicating that efficient activation of TNF production induced by these compounds required a cell-to-cell contact. Finally, preincubation experiments allowed us to demonstrate that activation of V gamma 9V delta 2 T cells was strictly dependent on the presence of TUBag because preincubation of the targets with TUBag followed by a single wash abrogated the activation. Taken together, these results strongly suggest that activation of V gamma 9V delta 2 cells by TUBag occurs after binding of these compounds to (a) yet unidentified, highly conserved, and broadly distributed molecule(s). The results also suggest either that TUBag induces a very rapid and transient expression of a V gamma 9V delta 2 TCR ligand or, more likely, that TUBag is a low affinity component of a complex recognized by the V gamma 9V delta 2 TCR.

Early activation of human V gamma 9V delta 2 T cell broad cytotoxicity and TNF production by nonpeptidic mycobacterial ligands

Human V gamma 9V delta 2 T cells were shown recently to respond to nonpeptidic phosphorylated molecules of mycobacterial origin (previously referred to as TUBag). To investigate the early events of V gamma 9V delta 2 T cell activation, we have analyzed induction of cytotoxicity and TNF production of T cell clones by these molecules. We showed that within minutes after exposure, TUBag induced cytotoxicity of V gamma 9V delta 2 CTL (but not of CTL expressing other TCR V gamma/V delta or V alpha/V beta regions) against a broad set of target cells, including effector cells themselves. Induction of V gamma 9V delta 2 cytotoxicity by TUBag was blocked by anti-TCR mAbs and was abrogated after dephosphorylation of TUBag. Similarly, TUBag, but not dephosphorylated TUBag, induced massive TNF production by V gamma 9V delta 2 T cell clones only, which already was significant 20 min after exposure. Of note, only basal amounts of TNF were produced when cells were maintained in suspension in the presence of TUBag, indicating that efficient activation of TNF production induced by these compounds required a cell-to-cell contact. Finally, preincubation experiments allowed us to demonstrate that activation of V gamma 9V delta 2 T cells was strictly dependent on the presence of TUBag because preincubation of the targets with TUBag followed by a single wash abrogated the activation. Taken together, these results strongly suggest that activation of V gamma 9V delta 2 cells by TUBag occurs after binding of these compounds to (a) yet unidentified, highly conserved, and broadly distributed molecule(s). The results also suggest either that TUBag induces a very rapid and transient expression of a V gamma 9V delta 2 TCR ligand or, more likely, that TUBag is a low affinity component of a complex recognized by the V gamma 9V delta 2 TCR.

Stimulation of human gamma delta T cells by nonpeptidic mycobacterial ligands

Most human peripheral blood gamma delta T lymphocytes respond to hitherto unidentified mycobacterial antigens. Four ligands from Mycobacterium tuberculosis strain H37Rv that stimulated proliferation of a major human gamma delta T cell subset were isolated and partially characterized. One of these ligands, TUBag4, is a 5' triphosphorylated thymidine-containing compound, to which the three other stimulatory molecules are structurally related. These findings support the hypothesis that some gamma delta T cells recognize nonpeptidic ligands.

Validité de l'analyse des sacs fécaux pour l'étude du régime alimentaire des jeunes au nid de la linotte mélodieuse (Carduelis cannabina)

Diet was studied in nestlings of the European Linnet (Carduelis cannabina L.) by analysing fecal sacs, the only method that allows continuous sampling of the diet to the end of the nesting period. The validity of the method was tested by comparing the results of the analysis with the composition of the stomach contents of nestlings that died during nesting. This study was carried out in a moor surrounded by hedges, at Campénéac, in Brittany, France. There is a strong correlation between the mean composition of the fecal sacs and that of the stomach contents, but biases were found. Animal matter, which represents a minimal fraction of the food and is given only occasionally to the chicks during the first days of feeding, leaves practically no traces in fecal sacs. Moreover, a few species of seeds that are almost completely assimilated, e.g. Brassica napus and Euphorbia helioscopia, can be greatly underestimated in the analysis of fecal sacs. As these species may be at certain times the preferred food of the chicks, specific correction factors have been calculated to compensate for the biases. Our results indicate that by analysing the fecal sacs one can quickly identify and quantify the diet of nestlings and that with a relatively small number of samples; it constitutes therefore a reliable and rapid technique.[Journal translation]

[Comparative results of 99mTc scintigraphy and computerized tomography after contrast injection in cerebral pathology (author's transl)]

140 patients have been investigated by means of computerized tomography (CT) after contrast injection and radionuclide scan (RN scan). For patients with stroke (56 cases), RN uptake was more frequent (80%) at the 15th day of evolution, enhancement of hypodense images at CT reaches 100% at the 21st day. For the others pathologies (hematoma, tumors), the main difference between both examinations, was the volume of the lesions detected. RN uptake and CT enhancement both show the same blood brain barrier disturbance.

[Results of brain tomography in acute lymphoblastic leukemia in children]

Computerised axial tomography (CAT scan) was performed in 22 children with acute lymphoblastic leukaemia and in 13 the results were normal. In the other nine, various lesions were observed; namely intra-parenchymal lesions of density of (3 cases, one of which was calcified), intra-parenchymal lesions of decreased density (2 cases) and ventricular dilatation (7 cases). The role of the disease and of the treatment (intra-thecal methotrexate, cranial irradiation) in the development of these lesions is discussed. The CAT scan is an excellent method of monitoring the neurological problems in acute lymphoblastic leukaemia.

[Anatomical and clinical considerations in aphasia: the value of tomodensitometry (author's transl)]

Tomometric tests were carried out in 54 patients with a clinical picture of stabilized or regressive aphasia, some time after the initial episode. The correlation between clinical and topographic findings were satisfactory in 90 p. 100 of the cases. The frequency of lesions extending into several lobes (70 cases) and of multiple lesions is stressed. There is a significant relationship between the severity of the clinical findings during tomometric testing and the volume or multiplicity of the lesions. The progression of the disease after 6 months, as studied in 31 patients, was also related to the volume of the lesion, but was not influenced by the presence of diffuse atrophy, except where the disease was deteriorating. The value of tomometry in the study of aphasia involves 3 factors: precise clinical and lesional correlation, and the effect of the volume of the lesion on its initial severity and progression. In the future, tomometry should enable a correlative symptomatic study of aphasic disorders to be made.

Cerebral blood flow and metabolism during etomidate anaesthesia in man

The effects of etomidate on regional cerebral blood flow (rc.b.f.) and cerebral metabolic rate for oxygen (CMRo2) were studied in seven patients undergoing diagnostic carotid angiography. Following determination of baseline rc.b.f. while awake, the patients were anaesthetized with a single dose of etomidate 15 mg. Thereafter, an infusion of etomidate (2 or 3 mg min-1) was administered. Etomidate decreased both rc.b.f.10 (mean decrease 34%) and CMRo2 (mean decrease 45%). It was concluded that etomidate is a potent cerebral metabolic depressant. Furthermore, the cerebrovascular reactivity to carbon dioxide was maintained under etomidate anaesthesia.

Effects of a diazepam-fentanyl mixture on cerebral blood flow and oxygen consumption in man

The effects of a mixture of diazepam and fentanyl on cerebral blood flow (c.b.f.) and cerebral metabolism of oxygen (CMRo2) were studied in eight normal subjects and 13 patients with organic brain disease. The coupling of flow and metabolism and the carbon dioxide responsiveness of the c.b.f. were studied also. In the normal subjects the injection of the mixture resulted in a significant decrease in c.b.f. (34%), and a similar decrease in CMRo2 (34.5%). The vasoreactivity of the brain to carbon dioxide was maintained. C.b.f. decreased in all patients with intracranial pathology.

Variations in the measurement of regional cerebral blood volume by CAT

The cerebral blood volume (CBV) has been measured by transverse axial tomography. The attenuation coefficient of 100 "pixels" located in a well determined region was measured before and after injection of a contrast material (Telebrix 38). The attenuation coefficient of blood samples was measured by CT in a phantom. Blood samples were drawn before and after injection at the same time as the tomographic section (time: half rotation of the scanner). The volume was calculated by the (formula: see text). The values obtained with very early measurements (1--5 min after injection), were very close to those measured by other methods (3--5 ml/100 ml). For 5 patients, the CBV was measured by the same method at different times: 20 measures between 2 and 50 min after the injection. The CBV seemed to vary in function with time according to the equation: CBV in ML%: ate-bt + Vo (t = time in minutes: a = integration constant, a = 1.94; b = time constant, b = 0.089; Vo = real CBV). The apparent variation of CBV was the result of two factors related to the blood-brain barrier, (1) water movement from the extravascular space towards the intravascular space, related to the hyperosmolarity of the contrast medium. The variations of osmolarity and haematocrit values measured after contrast injection did confirm this hypothesis; and (2) iodine movement from the intravascular space towards the extravascular space, due to the toxicity of the material (hyperosmolarity, Na ions, etc). The measurement of CBV by CT is only possible if the contrast materials do not modify the blood-brain barrier. The use of actual materials allows the study of the blood-brain barrier behaviour and enables to make an estimate of the cerebral extra-cellular space. But CT is not a right method of CBV measurement with the contrast medium in use nowadays.

Vascular thrombosis induced by direct electric current. A new technique for therapeutic embolisation; animal experimentation; first clinical applications

A first series of experiments showed that the passage of a direct current along a positive electrode immersed in heparinised blood caused the formation of an adhering clot whose diameter increased with time and current intensity. A second series of experiments was done on 10 rabbits as follows: under general anaesthesia, a catheter used as a guide to the positive electrode was surgically inserted in the abdominal aorta. The negative electrode was placed on the thigh. A direct current (10 mA, 10V) was applied for 10-20 min. The first two clinical applications in man of this new method of treatment by electric current thrombosis were carried out using catheterisation of branches of the external carotid and cervical arteries.

Cerebral blood volume and water extraction from cerebral parenchyma by hyperosmolar contrast media

The attenuation coefficients of cerebral parenchyma and systemic blood were simultaneously measured at varying times after injection of two contrast agents with differing osmolarities. Cerebral parenchyma was in fact denser than the theory would predict. The osmolarity of the iodinated contrast agents seems to play only a very minor part. However, liposolubility could perhaps explain the leakage of iodine across the BBB and thus the increase in the attenuation coefficient of cerebral parenchyma.

Prognostic value of rCBF measurements and CT in focal cerebral ischemia

CT is the most effective examination technique for studying the evolution of ischemic attacks, but if performed within the first 3 weeks it does not allow prognosis of possible evolution towards necrosis. CBF measurement and vasoreactivity tests under Althesin do allow this prognosis. Thirty patients whose evolution was checked clinically and by repeated CT examinations (89 in all) underwent CBF measurements (intra-arterial xenon 133) and vasoreactivity tests. In all cases (17 patients) where vasoreactivity had completely disappeared (inverse steal), the infarct evolved towards necrosis.

Comparative results of 99mTc-pertechnetate scintigraphy and computerized tomography after contrast injection in cerebral pathology

Fifty-six patients presenting acute cerebral ischemia were investigated by means of 160 CT and 90 RN scans. CT was positive before contrast injection in 90% of cases. A total of 120 CTs were done before and after contrast injection. Only 31% of the ischemic areas were enhanced. Out of 90 RN scans, 50 showed localized uptake. The peak of scintigraphic detection was found on the 15th day of evolution, while enhancement at CT was more frequent between the 15th and 21st days. For the hematomas (13 cases) detection by RN scan depends on the size of the lesion. Among the 47 patients presenting cerebral tumor, the RN uptake depends above all on the intensity of the BBB lesion. RN uptake and CT enhancement both show the same blood-brain barrier disturbance.

[Transverse axial computerised tomography of the brain in partial epilepsy]

Two hundred epileptics presenting with partial epileptic attacks were subjected to investigation by Acta-Scanner. Results were normal in 100 cases. Also found were 20 tumours (13 of them astrocytomas), 7 epileptogenic softenings, 41 cerebral atrophies, 8 of which were porencephalies, 5 calcifications (3 isolated, 2 multiple, connected with Bourneville's disease), 5 post-operative lesions and 22 dubious conditions. Various correlations between the results of scanning, the clinical findings and the E.E.G. are considered. The value of scanning in screening for tumours developing under the cloak of isolated epilepsy is emphasized and attention is drawn to certain difficulties of interpretation.

Cerebral ischemia with CT

One hundred fifty-eight patients with cerebral ischemia, and divided into four clinical groups were studied with CT. The results were correlated with those of angiography, scintigraphy and regional cerebral blood flow measurement. CT evolution was closely correlated with clinical and anatomical evolution. Changes in cerebral parenchyma density, in relation to the ischemic lesion, are the result of two phenomena: first, edema showing a fairly stable peak of intensity in the 2nd week and disappearing totally before the 20th day; and second, necrosis, variable in extent from patient to patient at the onset with subsequent evolution towards cavitation and thus a density similar to that of cerebro-spinal fluid.

Cerebral metastasis--a study of computerized tomography

Sixty-eight cases of metastases affecting 34 patients were studied by computerized tomography (CT) before and after the injection of an iodinated contrast medium. CT data provided a diagnosis in most cases. After injection of the contrast medium, a ring aspect was found in half the cases. This morphological feature is a sign of blood-brain barrier impairment crossed by the contrast medium. The low density area inside the ring is not caused by central necrosis, nor is it caused by too little contrast medium. The increase in density is a sign of extra-vascular loss of iodinated molecules in the peritumoral cerebral tissue. Performance of CT should be improved using specific tracers of the tumoral cells.

CT studies of tumors of the skull base, facial skeleton and nasopharynx

Fifty cases of tumors of the base of the skull, facial skeleton and nasopharynx were studied by CT. The tumoral densities were measured and compared to the pterygoid muscle density which was used as reference. Results showed no relationship between tumoral density and histology, and intravenous contrast medium injection was not useful. CT, however, does offer many advantages in the diagnosis of nasopharynx tumors, (5 cases) and in the determination of the extension of facial skeleton tumors.

[Evolutive aspects of cerebral vascular complications. Tomodensitometric study]

Seventy patients with clinical evidence of cerebral vascular accidents were studied by tomodensitometry. Forty-eight had clinical signs of acute ischaemia and, by means of 64 investigations, it was possible to follow the development of focal softening. Diagnostic difficulties encountered in the course of the first fortnight of development are described. Twenty-two patients exhibited clinical symptoms of meningeal or cerebro-meningeal haemorrhage. Eighteen haematomas were diagnosed and their development studied in 34 investigations.