Occupational pesticide exposure, cancer and chronic neurological disorders: A systematic review of epidemiological studies in greenspace workers.

CONTEXT: The greenspace sector includes a broad range of occupations: gardeners, landscapers, municipal workers, maintenance operators of public facilities, golf-course employees and other sports facilities, horticulturists, plant and tree nursery workers etc. The health impact of occupational pesticide exposure has mainly been studied among farmers. Other professionals such as greenspace workers are also extremely exposed, presenting specific exposure features (practices, types of pesticide used). The aim of this review was to summarize epidemiological literature that examine the relationship between pesticide exposure and the risk of cancer and long-term health effects in greenspace workers. METHOD: Six main groups of greenspace workers were identified and examined through a systematic literature review based on PubMed and Scopus. The studies were then grouped according to their design, health outcomes and the type of population studied. RESULTS: Forty-four articles were selected among the 1679 identified. Fifteen studies were conducted exclusively among greenspace workers, while ten also studied these workers with other pesticide applicators. Six were cohorts from the general population in which greenspace workers were identified. Elevated risks were found in several studies for leukaemia, soft-tissue sarcoma, multiple myeloma, non-Hodgkin lymphoma and Parkinson's disease. DISCUSSION: The majority of studies used rough parameters for defining exposure such as job titles which could lead to the misclassification of exposure, with the risk of false or positive negative conclusions. Health outcomes were mainly collected through registries or death certificates, and information regarding potential confounders was often missing. CONCLUSION: The review identified only 15 studies conducted exclusively among greenspace workers. Elevated risk was found for several sites of cancer and Parkinson's diseases. Further epidemiological research is needed, conducted specifically on these workers, to better characterize this population, its exposure to pesticides and the related health effects.

Pesticides Exposure by Air in Vineyard Rural Area and Respiratory Health in Children: A pilot study.

RATIONALE: Asthma, frequently associated with rhinitis, is the most common chronic disease in children, and a significant role is played by a range of environmental exposures. Among them, air pollution is of foremost concern. However, little is known about the impact of airborne pesticide exposure on children's respiratory health in rural areas. The objective of this study was to analyze the association between airborne pesticide exposure and asthma and rhinitis in children. METHODS: In a French vineyard rural area, children (3-10 years old) from 4 selected schools were invited to participate in this study over two periods: winter, with no or low air pesticide levels, and summer when fields are frequently treated with pesticides. Two health outcomes were considered: asthma and rhinitis symptoms (ISAAC questionnaire), and peak expiratory flow (PEF). A quantitative score of symptoms was built. Exposure to pesticides was evaluated 1) by measuring 56 pesticides in the ambient outdoor air around schools in the two periods and building a cumulative exposure index, and 2) by measuring ethylenethiourea (ETU) concentrations in urine in a subsample of children (n = 96), ETU being a urine biomarker of exposure to dithiocarbamates fungicides. Next, the association between pesticide exposure and respiratory health was studied using a logistic regression model, adjusted for confounders and respiratory status at baseline. RESULTS: 281 children participated in the study (47% girls, mean age: 7.5 yrs). 25% of the children were living on a farm. 22% had experienced wheezing at least once. 15.8% had asthma diagnosed by a doctor, 12% had current asthma and 35% had allergic rhinitis. The main pesticides detected in the ambient outdoor air around schools were fungicides (89,3%; mainly folpet and dithiocarbamates) and insecticides (10.6%). No association was found between the symptom score and pesticides in the outdoor air around schools during summer, when pesticides were applied to vineyards. However, an association was found between ETU urinary concentration (>0.974 µg/g creatinine) and asthma and rhinitis symptoms (OR=3.56; IC 95% 1.04-12.12). This result could be explained by extracurricular exposure, which was not considered in our air measurements in the schools. No association was found between peak expiratory flow and exposure to pesticides in the air. CONCLUSIONS: Children living in vineyard rural areas are at a higher risk of airborne dithiocarbamates exposure during the summer period. Despite the limited size of our sample, our results suggest possible links between some pesticide measurements and respiratory and allergic symptoms such as rhinitis.

Levels and determinants of pesticide exposure in re-entry workers in vineyards: results of the PESTEXPO study.

Physical contact with branches, leaves, fruit or vegetables in previously treated crops is responsible for the transfer of pesticides to the worker's skin in agricultural tasks such as harvesting, pruning, thinning, cutting or sorting. Few studies have documented workers' exposure during re-entry in vineyards. In the PESTEXPO study, we described levels of exposure and analyzed their determinants during re-entry and harvesting in vineyards in the Bordeaux area, France. Between 2002 and 2007, volunteers performing re-entry tasks (N=46 days) or harvesting (N=48 days) after dithiocarbamate or folpet treatment were observed. Detailed information on the tasks was collected and dermal contamination was assessed using patches placed on the skin and hand-washing at the end of each working phase. Daily median contamination was 1 967.7 µl of mixture during re-entry (90(e) percentile: 5 045.3 µl) and 18.7 µl during harvesting (90(e) percentile: 911.4 µl). The type of task was the parameter found to be the most strongly associated with contamination. For re-entry, the highest contaminations were observed during raising of wires and cutting of branches. During the harvest, the contamination was maximal for grape-picking. The delay since the last treatment and the rate of active ingredient per hectare played a role, together with other factors such as meteorological factors, crop and farm characteristics, gloves and clothes. Our results underline the necessity to take into account exposures during re-entry and harvest when considering pesticide exposure, both for epidemiological research and preventive action.

[Chronic central nervous system effects of pesticides: state-of-the-art]. / Effets chroniques des pesticides sur le système nerveux central : état des connaissances épidémiologiques.

BACKGROUND: Given the neurotoxic properties of pesticides, suggested by experimental results and clinical observations, many epidemiological studies have investigated neurological effects following acute or chronic exposure to pesticides. This review provides an overview of current knowledge about pesticide effects on the central nervous system: neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis), cognitive disorders, and psychiatric disorders (mood disorders, anxiety, depression and suicide). RESULTS: Parkinson's disease, the most widely studied in relation with pesticide exposure, particularly with insecticides and herbicides, was observed to be a risk factor of the disease. Evidence is scarce for Alzheimer's disease and amyotrophic lateral sclerosis, but quite consistent. Cognitive and psychiatric disorders were often observed in relation with organophosphate insecticide exposure. Cognitive disorders were found associated with acute and chronic exposures, and psychiatric disorders mostly with poisonings. These epidemiologic studies were limited by a lack of detailed and reliable exposure assessment. The role of genetic susceptibilities has been recently observed, but must be further investigated.

Maternal occupational exposures to nanoscale particles and small for gestational age outcome in the French Longitudinal Study of Children.

OBJECTIVES: To investigate the association between maternal occupational exposures to nanoscale particles (NPs) during pregnancy and small for gestational age (SGA). METHODS: This study included 11,224 mothers and singleton birth pairs from the French Longitudinal Study of Children (ELFE cohort), which included infants born after 33 weeks of gestation or more in continental France in 2011. Mothers who did not work during pregnancy were excluded from the analyses. Maternal occupational exposures to NPs was estimated using a job-exposure matrix for the probability (>50%: occupationally exposed group, n = 569; 0%: occupationally non-exposed group, n = 9113; between these two thresholds: uncertain group, n = 1542) and frequency of exposure. Associations were estimated from multivariate logistic regression models for occupationally exposed vs occupationally unexposed groups in a first analysis, and with the frequency-weighted duration of work for the occupationally exposed group only in a second analysis. RESULTS: Among working mothers, 5.1% were occupationally exposed to NPs. Maternal occupational exposures to NPs was associated with SGA (ORa = 1.63, 95% CI: 1.22, 2.18). The frequency-weighted duration of work for the occupationally exposed group (n = 569) was not associated with SGA (ORa = 1.02, 95% CI: 0.97, 1.08) in adjusted analyses. CONCLUSIONS: These results, showing a significant association between occupational exposures to NPs and SGA, should encourage further studies to examine the adverse effect of NPs exposure on fetal development.

Maternal cumulative exposure to extremely low frequency electromagnetic fields and pregnancy outcomes in the Elfe cohort.

OBJECTIVES: To study the relations between maternal cumulative exposure to extremely low frequency electromagnetic fields (ELF EMF) and the risk of moderate prematurity and small for gestational age within the Elfe cohort. METHODS: The Elfe study included 18,329 infants born at 33weeks of gestation or more in France in 2011 and was designed to follow the children until 20years of age. Gestational age and anthropometric data at birth were collected in medical records and small for gestational age was defined according to a French customized growth standard. During interviews, mothers were asked to report their job status during pregnancy. If employed, their occupation was coded according to the International Standard Classification of Occupations 1988 and the date on which they stopped their work was recorded. Cumulative exposure to ELF EMF during pregnancy was assessed, for both mothers who worked and those who did not during pregnancy, using a recently-updated job-exposure matrix (JEM). Cumulative exposure was considered as a categorical variable (<17.5, 17.5-23.8, 23.8-36.2, 36.2-61.6 or ≥61.6µT-days), a binary variable (<44.1 and ≥44.1µT-days) and a continuous variable. Associations were analyzed by logistic regression, adjusting for the mother's lifestyle factors, sociodemographic characteristics and some mother's medical history during and before pregnancy. Analyses were restricted to single births and to complete values for the pregnancy outcomes (n=16,733). RESULTS: Cumulative exposure was obtained for 96.0% of the mothers. Among them, 37.5% were classified in the 23.8-36.2µT-days category, but high exposures were rare: 1.3% in the ≥61.6µT-days category and 5.5% in the ≥44.1µT-days category. No significant association was observed between maternal cumulative exposure and moderate prematurity and small for gestational age in this exposure range. CONCLUSION: This large population-based study does not suggest that maternal exposure to ELF EMF during pregnancy is highly associated with risks of moderate prematurity or small for gestational age.

Definition of a T-cell receptor beta gene core enhancer of V(D)J recombination by transgenic mapping.

V(D)J recombination in differentiating lymphocytes is a highly regulated process in terms of both cell lineage and the stage of cell development. Transgenic and knockout mouse studies have demonstrated that transcriptional enhancers from antigen receptor genes play an important role in this regulation by activating cis-recombination events. A striking example is the T-cell receptor beta-chain (TCRbeta) gene enhancer (Ebeta), which in the mouse consists of at least seven nuclear factor binding motifs (betaE1 to betaE7). Here, using a well-characterized transgenic recombination substrate approach, we define the sequences within Ebeta required for recombination enhancer activity. The Ebeta core is comprised of a limited set of motifs (betaE3 and betaE4) and an additional previously uncharacterized 20-bp sequence 3' of the betaE4 motif. This core element confers cell lineage- and stage-specific recombination within the transgenic substrates, although it cannot bypass the suppressive effects resulting from transgene integration in heterochromatic centromeres. Strikingly, the core enhancer is heavily occupied by nuclear factors in immature thymocytes, as shown by in vivo footprinting analyses. A larger enhancer fragment including the betaE1 through betaE4 motifs but not the 3' sequences, although active in inducing germ line transcription within the transgenic array, did not retain the Ebeta recombinational activity. Our results emphasize the multifunctionality of the TCRbeta enhancer and shed some light on the molecular mechanisms by which transcriptional enhancers and associated nuclear factors may impact on cis recombination, gene expression, and lymphoid cell differentiation.

Pesticide exposure of non-occupationally exposed subjects compared to some occupational exposure: a French pilot study.

Data about non-dietary exposure to different chemical classes of pesticides are scarce, especially in France. Our objective was to assess residential pesticide exposure of non-occupationally exposed adults, and to compare it with occupational exposure of subjects working indoors. Twenty unexposed persons, five gardeners, seven florists and nine veterinary workers living in Paris area were recruited. Nineteen residences, two greenhouses, three florist shops and three veterinary departments were then sampled. Thirty-eight insecticides, herbicides and fungicides were measured in indoor air with an air sampler for 24 h, and on hands by wiping them with isopropanol-wetted swabs. After extraction, samples were analysed by gas and high-performance liquid chromatography. Seventeen different pesticides were detected at least once in indoor air and twenty-one on the hands. An average of 4.2+/-1.7 different pesticides was detected per indoor air sample. The organochlorines lindane, alpha-endosulfan and alpha-HCH were the most frequently detected compounds, in 97%, 69% and 38% of the samples, respectively. The organophosphates dichlorvos and fenthion, the carbamate propoxur and the herbicides atrazine and alachlor were detected in more than 20% of the air samples. Indoor air concentrations were often low, but could reach 200-300 ng/m(3) in residences for atrazine and propoxur. Propoxur levels significantly differed between the air of veterinary places and other places (Kruskal-Wallis test, p<0.05) and dieldrin levels between residences and workplaces (p<0.05). There was a greater number of pesticides on hands than in air, with an average of 6.3+/-3.3 different pesticides detected per sample, the most frequently detected being malathion, lindane and trifluralin, in more than 60% of the subjects. Maximal levels (up to 1000-3000 ng/hands) were observed either in the general population or in workers, depending on the pesticide. However, no significant difference was observed between workers and general population handwipe pesticide levels. As expected, gardeners were exposed to pesticides sprayed in greenhouses. Florists and veterinary workers, whose pesticide exposure had not been described until now, were also indirectly exposed to pesticides used for former pest control operations. Overall, general population was exposed to more various pesticides and at levels sometimes higher than in occupational places. The most frequent pesticides in residences were not the same as in US studies but levels were similar. These preliminary results need to be confirmed in a greater number of residences from different parts of the country, in order to better assess pesticide exposure of the general population and its influencing factors.

Relationship between phagosome acidification, phagosome-lysosome fusion, and mechanism of particle ingestion.

The fate of pathogens ingested by macrophages is dependent on phagosome acidification and fusion with different intracellular vesicles. Whereas the mode of particle recognition by the phagocyte seems the main determinant of phagosome-lysosome fusion, the influence of membrane reorganization, fusion events, and cell activation in phagosome acidification is not well known. We looked for a relationship between the nature of receptors involved in phagocytosis, phagosome acidification, and phagosome-lysosome fusion. Murine macrophage-like P388D1 cells were made to ingest sheep erythrocytes coated with immunoglobulin G (EIgG) or IgM and complement (EIgMC) or treated with glutaraldehyde and periodate (EGP). The following results were obtained: (1) As expected, the adhesion of the three particle types was differentially inhibited by monoclonal antibodies specific for Fc gamma RII and CD11b/CD18. (2) The phagosomes containing all three particle types displayed similar acidification kinetics with a pH decrease to 6 within the first 10 min after ingestion. (3) Only phagosomes containing EIgG or EIgMC were fused with peroxidase-loaded secondary lysosomes. (4) Coating EGP with IgG only partially restored fusion, even when the surface density of IgG was markedly higher than found on EIgG. It is concluded that phagosome acidification and fusion are regulated by different mechanisms. Also, the lack of fusion observed with EGP is not entirely accounted for by the absence of stimulation of suitable receptors on the phagocyte membrane, because it cannot be restored by providing such a stimulus.

Presynaptic NMDA receptors: Roles and rules.

NMDA receptors (NMDARs) are glutamate-gated ion channels widely expressed in the central nervous system (CNS) and endowed with unique biophysical, pharmacological and signaling properties. These receptors are best known for their critical roles in synaptic plasticity and their implications in a variety of neurological and psychiatric disorders. Since their discovery three decades ago, NMDARs have been thoroughly studied as components of postsynaptic excitatory potentials. Early on, however, both anatomical and physiological evidence pointed out to the existence of NMDARs away from the postsynaptic density. Some were found to be extrasynaptic, while others seemed to be specifically present at presynaptic (i.e. axonal) elements. Although presynaptic NMDARs (preNMDARs) were at first thought to be exceptional, there is now strong evidence that these receptors are relatively widespread in the CNS and regulate synaptic strength in specific sets of synapses. In this review, we compile our current knowledge on preNMDARs, presenting their anatomical distribution, developmental regulation, subunit composition, activation mechanisms as well as their downstream effects on synapse function. Contentious issues that animate the field are also discussed. Finally, particular emphasis is put on the molecular and cellular diversity of preNMDARs which translates into a variety of effects, both short- and long-term, on synaptic efficacy. Overshadowed by their postsynaptic counterparts, preNMDARs are progressively emerging as important regulators of neuronal signaling.

High benzo[a]pyrene diol-epoxide DNA adduct levels in lung and blood cells from individuals with combined CYP1A1 MspI/Msp-GSTM1*0/*0 genotypes.

Levels of anti-benzo[a]pyrene diol-epoxide DNA adducts were analysed by high-pressure liquid chromatography/fluorimetric detection in non-tumorous lung tissues from 20 lung cancer patients and in white blood cells from 20 polycyclic aromatic hydrocarbon exposed coke oven workers. All were current tobacco smokers. CYP1A1 mutations (MspI at 6235 nt, Ile-Val462) and GSTM1 deletion polymorphisms in each individual were analysed in genomic DNA by PCR/restriction fragment length polymorphism. Independently of the CYP1A1 genotype (1) all 23 samples in the two groups with non-detectable adducts (< 0.2 per 10(8) nt) were of GSTM1 active genotype; (2) the 17 samples with detectable adducts (> or = 0.2 per 10(8) nt) in the two groups were GSTM1*0/*0. The difference in adduct levels between GSTM1*0/*0 and GSTM1 active genotype was highly significant (p < 0.00005). Among GSTM1-deficient individuals (n = 17), a subgroup of 14 individuals with CYP1A1*1/*1 (wild-type, n = 7) or heterozygous genotype (*1/*2A or *1/*2B, n = 7) showed low levels of BPDE DNA-adducts (range: 0.2-1.3 per 10(8) nt). (3) Three individuals with the rare combination CYP1A1*2A/*2A or *2A/*B and GSTM1*0/*0 showed significantly higher adduct levels (median: 17.4 adducts/10(8) nt, range 1.9-44; p = 0.017). Therefore, combination of homozygous mutated CYP1A1 and GSTM1*0/*0 genotypes lead, at a similar or even lower smoking dose, to a stronger increase of anti-benzo[a]pyrene diol-epoxide DNA adduct levels than found in individuals with CYP1A1 and GSTM1 wild-type. These data provide a mechanistic understanding of epidemiological studies that correlated these 'at risk' genotypes with increased smoking-related lung cancers.

Biochemical analysis of interleukin-2 receptor beta chain phosphorylation by p56(lck).

Tyrosine phosphorylation of multiple proteins, including the receptor itself, is an initial event in IL-2 signaling and leads to recruitment of SH2 or PTB domain-containing proteins to the receptor. In this study, we have used subdomains of the IL-2 receptor beta chain (IL-2Rbeta) expressed in Escherichia coli as GST fusion proteins to identify the tyrosine residues that could be phosphorylated by p56(lck), one of the critical tyrosine kinases activated by IL-2. We report that recombinant p56(lck) phosphorylates in vitro tyrosine residues within the IL-2Rbeta chain but not those within the IL-2Rgamma chain. p56(lck) phosphorylates tyrosine residues 355, 358 and 361 but not 338 of the IL-2Rbeta chain acidic subdomain. Interestingly, phosphorylation of Tyr-358 appears to require the presence of either Tyr-355 or Tyr-361. p56(lck) also phosphorylates very efficiently the two tyrosines present in the IL-2Rbeta chain C-terminal region, Tyr-392 and Tyr-510. We also investigated the association of p56(lck) with the IL-2Rbeta chain which was found to depend on a short stretch of the IL-2Rbeta chain acidic subdomain, and to be independent of the presence of its tyrosine residues.

Urinary excretion of nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for nasopharyngeal carcinoma in southern China.

The hypothesis that endogenous synthesis of nitrosamines from dietary precursors is a risk factor for nasopharyngeal carcinoma (NPC) in China was tested by applying the nitrosoproline (NPRO) test to subjects living in high- and low-risk districts for NPC in Zangwu county, Guangxi region, in southern China. Samples of 12-h urine were collected from 77 subjects: (a) before any treatment; (b) after ingestion of proline; and (c) after ingestion of proline together with vitamin C. NPRO, other nitrosamino acids, and nitrate were measured as indices of exposure to preformed and endogenously formed nitrosamines or their precursors. The NPRO level after proline intake was significantly increased in subjects from the high-risk area (P = 0.012) and markedly reduced after ingestion of ascorbic acid (P = 0.007), but such an effect was not seen in subjects from the low-risk area. Levels of N-nitrosothiazolidine-4-carboxylic acid and the sum of nitrosamino acids in subjects in the high-risk area were significantly reduced by ascorbic acid (P < 0.01) but were not reduced in subjects from the low-risk area. The urinary nitrate level was about twice as high in subjects from the high-risk area. In subjects from high- and low-risk areas combined, NPRO levels in any of the three dose groups were highly correlated with nitrate levels (P = 0.0001). These results demonstrate a higher potential for endogenous nitrosation in subjects living in the high-risk area of NPC and suggest the occurrence of nitrosation inhibitors in the diet consumed in the low-risk area.(ABSTRACT TRUNCATED AT 250 WORDS)

Headache as an epileptic manifestation.

In two cases, depth electrode studies and behavioral recordings indicated that headache was a clinical manifestation of ictal activity. The epileptogenic focus was found in the right limbic system, and right temporal lobectomy relieved the headaches.

The lateralizing and localizing value of adversion in epileptic seizures.

We studied 24 patients who had adversion as the first clinical manifestation of seizures. Seizures were recorded with depth electrodes as part of the evaluation for possible surgery for epilepsy. Head rotation did not help to lateralize the epileptic focus clinically, because deviations occurred ipsilaterally to the EEG focus in some patients, and because some patients had head rotation in either direction despite a unifocal epileptogenic abnormality. Furthermore, no cortical localization was consistently linked to either direction or degree of adversion. Adversion has no consistent lateralizing or localizing value.

Naloxone and focal epilepsy: a study with depth electrodes.

Intravenous injections of naloxone (0.8 to 2.4 mg) were given to patients with focal epilepsy who had had electrodes implanted in cortical and subcortical structures. There were no changes in interictal spike activity, responses to electrical stimulation, of frequency of spontaneous seizures. These data do not support the hypothesis that opiate peptides are involved in human focal epilepsy.

Sleep and temporal lobe epilepsy: a case study with depth electrodes.

We studied a patient with hippocampal epilepsy who had frequent nocturnal and diurnal seizures. Depth electrode recording showed that focal seizure discharges in the right hippocampus were of shorter duration in REM and non-REM sleep. However, awakening, especially from REM sleep or shortly after a REM period, facilitated the occurrence of a generalized seizure. There was no ultradian fluctuation in frequency or duration of seizure during diurnal recording. Night terrors (but not nightmares) disappeared after right temporal lobectomy, suggesting that pavor nocturnus was an ictal manifestation in this case.

Localization of NADPH-protochlorophyllide reductase in plastids of barley at different greening stages.

The localization of protochorophyllide (Pchlide) and of NADPH-protochlorophyllide oxidoreductase (POR, EC 1.6.99.1) within (etio)chloroplasts has been investigated at selected stages of greening of barley seedlings. Pchlide pigment and POR protein contents were evaluated in different plastid membrane fractions by fluorescence spectroscopy and immunoblot analysis using a monospecific polyclonal antibody raised against the purified enzyme. Fluorescence analysis showed the presence of Pchlide in both the envelope and thylakoid membranes. During greening, the Pchlide content, expressed on a total protein basis, decreased in thylakoid membranes, whereas it increased in the envelope membranes. POR proteins were detected mainly in thylakoid membranes at early greening stages. In contrast, the weak amount of POR proteins was associated more specifically with envelope membranes of mature chloroplasts. Whatever the greening stage, thylakoid-bound Pchlide and POR proteins were more abundant in the thylakoid regions which remained unsolubilized after mild Triton treatment used as standard procedure to prepare PS II particles. This suggests the preferential association of Pchlide and POR to the appressed regions of thylakoids.

In vivo localization of brain sulci by arteriography: a stereotactic anatomoradiological study.

The authors studied the course of the cortical arteries using the Talairach stereotactic system (orthogonal 4.8 m teleradiography, with rigid fixation of the skull in the stereotactic frame) in both anatomical specimens and normal bilateral carotid angiographies of epileptic patients. Anatomoradiological correlations between arterial patterns and underlying brain surface were identified by detailed 3-dimensional analysis of brain-skull preparations, where gyri and injected arteries were dissected progressively with stereotactic X-ray and photographic pictures taken at each step. The vascular landmarks so identified were studied in stereoscopic arteriographies that give a direct visualization of the spatial relationships of the arterial tree moulding the cortical surface thus allowing the recognition of the localization of the principal gyri and sulci. The latter were drawn on stereotactic diagrams. The basic sulcal pattern as shown by the arteries is strikingly symmetrical in both hemispheres of the same individual, in spite of variability in branching of the arterial tree. The disposition of the vascular landmarks in the retroinsular region reflects the left-right asymmetry of the planum temporale that can be recognized in vivo. This can give a clue to the study of anatomofunctional correlations with regard to speech dominance. A limited first series studied in this respect strongly suggests a close relationship between anatomical and functional asymmetry of the human cerebral hemispheres. Generally speaking, the authors feel that 3- dimensional, anatomical interpretation of angiography permits a direct localization of brain structures including the cortex, that can be used instead of indirect localization landmarks in stereotactic explorations, and further, that the wealth of anatomical information that can be drawn from angiography with their method may be helpful in diagnosis or for planning surgery.

A fixation procedure for ultrastructural investigation of synaptic connections in resected human cortex.

Electron microscopic investigations of the fine circuitry of human central nervous system require a well-preserved tissue ultrastructure. Because the deterioration of subcellular structures occurs rapidly in postmortem human brain, the use of a fixation by immersion of surgically resected human nervous tissue would be advantageous to investigate directly its synaptic circuitry. To obtain an optimal preservation of subcellular elements in immersion-fixed brain tissue, different conditions of fixation were first tested on 400 microns-thick sections of rat neocortex. Parameters tested were temperature of the fixative solution, concentrations of glutaraldehyde and of cacodylate buffer with or without microwave irradiation, and finally, the presence of dimethyl sulfoxide. The best ultrastructural preservation was obtained by immersing the tissue in 0.1 M cacodylate buffer, 3.0 mM CaCl2, 2% paraformaldehyde, 2.5% glutaraldehyde, and 2.5% dimethyl sulfoxide at 37 degrees C for 5 min and then at 4 degrees C for 4 h. This procedure of fixation was then applied to human neocortical tissue resected to alleviate temporal lobe epilepsy. This method led to good tissue preservation in addition to retaining the antigenicity to the inhibitory amino acid neurotransmitter, gamma-aminobutyric acid (GABA). Therefore, the tissue preservation obtained would permit these chemically defined connections to be investigated quantitatively at the electron microscopic level in resected human cortex.