Digestive symptoms in daily life of chronic adrenal insufficiency patients are similar to irritable bowel syndrome symptoms

Gastrointestinal symptoms are frequent in acute adrenal insufficiency. Although digestive symptoms can significantly reduce quality of life, they are rarely described in patients with treated chronic adrenal insufficiency (CAI). We aimed to characterize digestive symptoms in CAI patients. We used the section pertaining functional bowel disorders of the Rome IV questionnaire. A questionnaire was published on the website of the non-profit patient association "Adrenals" (NPPA of CAI patients) for five months. Information on demographics, characteristics of adrenal insufficiency, digestive symptoms and quality of life was collected. The relatives of CAI patients served as a control group. We analyzed responses of 33 control subjects and 119 patients (68 primary adrenal insufficiency (PAI), 30 secondary adrenal insufficiency (SAI) and 21 congenital adrenal hyperplasia (CAH)). Abdominal pain at least once a week over the past 3 months was reported by 40%, 47% and 33% of patients with PAI, SAI and CAH respectively versus 15% for the controls (p = 0.01). Symptoms were consistent with the Rome IV criteria for irritable bowel syndrome in 27%, 33% and 33% of patients respectively versus 6% for the controls (p < 0.0001). Quality of life was described as poor or very poor in 35%, 57% and 24% of patients respectively versus 5% for the controls (p < 0.0001). In conclusion, digestive symptoms are frequent and incapacitating in CAI patients and similar to symptoms of irritable bowel syndrome in 30% of CAI patients. Assessment and management of digestive symptoms should be considered a priority for physicians treating patients with CAI.

Mutant Huntingtin stalls ribosomes and represses protein synthesis in a cellular model of Huntington disease

The polyglutamine expansion of huntingtin (mHTT) causes Huntington disease (HD) and neurodegeneration, but the mechanisms remain unclear. Here, we found that mHtt promotes ribosome stalling and suppresses protein synthesis in mouse HD striatal neuronal cells. Depletion of mHtt enhances protein synthesis and increases the speed of ribosomal translocation, while mHtt directly inhibits protein synthesis in vitro. Fmrp, a known regulator of ribosome stalling, is upregulated in HD, but its depletion has no discernible effect on protein synthesis or ribosome stalling in HD cells. We found interactions of ribosomal proteins and translating ribosomes with mHtt. High-resolution global ribosome footprint profiling (Ribo-Seq) and mRNA-Seq indicates a widespread shift in ribosome occupancy toward the 5' and 3' end and unique single-codon pauses on selected mRNA targets in HD cells, compared to controls. Thus, mHtt impedes ribosomal translocation during translation elongation, a mechanistic defect that can be exploited for HD therapeutics.

A Mitochondrial Micropeptide Is Required for Activation of the Nlrp3 Inflammasome

Functional peptides encoded by short open reading frames are emerging as important mediators of fundamental biological processes. In this study, we identified a micropeptide produced from a putative long noncoding RNA (lncRNAs) that is important in controlling innate immunity. By studying lncRNAs in mice macrophages, we identified lncRNA 1810058I24Rik, which was downregulated in both human and murine myeloid cells exposed to LPS as well as other TLR ligands and inflammatory cytokines. Analysis of lncRNA 1810058I24Rik subcellular localization revealed that this transcript was localized in the cytosol, prompting us to evaluate its coding potential. In vitro translation with ³⁵S-labeled methionine resulted in translation of a 47 aa micropeptide. Microscopy and subcellular fractionation studies in macrophages demonstrated endogenous expression of this peptide on the mitochondrion. We thus named this gene mitochondrial micropeptide-47 (Mm47). Crispr-Cas9-mediated deletion of Mm47, as well as small interfering RNA studies in mice primary macrophages, showed that the transcriptional response downstream of TLR4 was intact in cells lacking Mm47. In contrast, Mm47-deficient or knockdown cells were compromised for Nlrp3 inflammasome responses. Activation of Nlrc4 or Aim2 inflammasomes were intact in cells lacking Mm47. This study therefore identifies, to our knowledge, a novel mitochondrial micropeptide Mm47 that is required for the activation of the Nlrp3 inflammasome. This work further highlights the functional activity of short open reading frame-encoded peptides and underscores their importance in innate immunity.

Genome editing in primary cells and in vivo using viral-derived Nanoblades loaded with Cas9-sgRNA ribonucleoproteins

Programmable nucleases have enabled rapid and accessible genome engineering in eukaryotic cells and living organisms. However, their delivery into target cells can be technically challenging when working with primary cells or in vivo. Here, we use engineered murine leukemia virus-like particles loaded with Cas9-sgRNA ribonucleoproteins (Nanoblades) to induce efficient genome-editing in cell lines and primary cells including human induced pluripotent stem cells, human hematopoietic stem cells and mouse bone-marrow cells. Transgene-free Nanoblades are also capable of in vivo genome-editing in mouse embryos and in the liver of injected mice. Nanoblades can be complexed with donor DNA for "all-in-one" homology-directed repair or programmed with modified Cas9 variants to mediate transcriptional up-regulation of target genes. Nanoblades preparation process is simple, relatively inexpensive and can be easily implemented in any laboratory equipped for cellular biology.

PDZ domain-binding motif of Tax sustains T-cell proliferation in HTLV-1-infected humanized mice

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATLL), an aggressive malignant proliferation of activated CD4+ T lymphocytes. The viral Tax oncoprotein is critically involved in both HTLV-1-replication and T-cell proliferation, a prerequisite to the development of ATLL. In this study, we investigated the in vivo contribution of the Tax PDZ domain-binding motif (PBM) to the lymphoproliferative process. To that aim, we examined T-cell proliferation in humanized mice (hu-mice) carrying a human hemato-lymphoid system infected with either a wild type (WT) or a Tax PBM-deleted (ΔPBM) provirus. We observed that the frequency of CD4+ activated T-cells in the peripheral blood and in the spleen was significantly higher in WT than in ΔPBM hu-mice. Likewise, human T-cells collected from WT hu-mice and cultivated in vitro in presence of interleukin-2 were proliferating at a higher level than those from ΔPBM animals. We next examined the association of Tax with the Scribble PDZ protein, a prominent regulator of T-cell polarity, in human T-cells analyzed either after ex vivo isolation or after in vitro culture. We confirmed the interaction of Tax with Scribble only in T-cells from the WT hu-mice. This association correlated with the presence of both proteins in aggregates at the leading edge of the cells and with the formation of long actin filopods. Finally, data from a comparative genome-wide transcriptomic analysis suggested that the PBM-PDZ association is implicated in the expression of genes regulating proliferation, apoptosis and cytoskeletal organization. Collectively, our findings suggest that the Tax PBM is an auxiliary motif that contributes to the sustained growth of HTLV-1 infected T-cells in vivo and in vitro and is essential to T-cell immortalization.

The viral Tax oncoprotein is a critical contributor to the development of adult T-cell leukemia/lymphoma, an aggressive malignant proliferation of T lymphocytes. Tax contains a PDZ domain-binding motif (PBM) that favors the interaction with several cellular PDZ proteins. Here, we compare the in vivo involvement of the Tax PBM in humanized mice infected with either a full-length provirus or a Tax PBM-deleted provirus. We observe that the establishment of the sustained lymphoproliferation in the peripheral blood of infected mice is dependent on the Tax PBM. Furthermore, binding of the Tax PBM to the PDZ Scribble protein correlated with perturbations of cytoskeletal organization and cell polarity. In addition, genome-wide transcriptomic analyses strongly suggest that the association of Tax PBM with cellular PDZ proteins results in the expression of several genes involved in proliferation, apoptosis and cytoskeletal organization. Collectively, these results indicate that the Tax PBM is an auxiliary motif that contributes to the growth of HTLV-1 infected T-cells. As a consequence, targeting the PBM/PDZ nodes using small peptides may have the potential to antagonize the Tax-induced lymphoproliferation, offering a novel strategy for the treatment of this disease.

A Long Noncoding RNA lincRNA-EPS Acts as a Transcriptional Brake to Restrain Inflammation

Long intergenic noncoding RNAs (lincRNAs) are important regulators of gene expression. Although lincRNAs are expressed in immune cells, their functions in immunity are largely unexplored. Here, we identify an immunoregulatory lincRNA, lincRNA-EPS, that is precisely regulated in macrophages to control the expression of immune response genes (IRGs). Transcriptome analysis of macrophages from lincRNA-EPS-deficient mice, combined with gain-of-function and rescue experiments, revealed a specific role for this lincRNA in restraining IRG expression. Consistently, lincRNA-EPS-deficient mice manifest enhanced inflammation and lethality following endotoxin challenge in vivo. lincRNA-EPS localizes at regulatory regions of IRGs to control nucleosome positioning and repress transcription. Further, lincRNA-EPS mediates these effects by interacting with heterogeneous nuclear ribonucleoprotein L via a CANACA motif located in its 3' end. Together, these findings identify lincRNA-EPS as a repressor of inflammatory responses, highlighting the importance of lincRNAs in the immune system.

[An intimate look at the viral replication cycle through ribosome profiling]

Next Generation Sequencing (NGS) techniques have revolutionized most biomedical research fields over the past decade by allowing a broader vision on biological processes that occur at the molecular level. Among these, ribosome profiling or footprinting is a powerful tool to study mRNA translation in a transcriptome-wide manner. Ribosome profiling has been used to study the impact of translational control of gene expression under many different cellular conditions including viral infections. Indeed, translation is a critical step during the viral replication cycle in which the infected cell is embezzled to produce viral proteins. Ribosome profiling tools can provide new insights on viral translation by monitoring ribosome binding to viral and cellular RNAs with a high definition during the time course of an infection. Here, we describe the potential uses of ribosome profiling for the understanding of viral translational control and the impact of viral infection on host gene expression. We also discuss the main limitations and biases related to the technique that need to be taken into account for its use.

Lack of referral for genetic counseling and testing in BRCA1/2 and Lynch syndromes: a nationwide study based on 240,134 consultations and 134,652 genetic tests

Based on nationwide data from the French national cancer institute (INCa), we analyzed the evolution of cancer genetics consultations and testing over time, and the uptake of targeted tests in relatives of families with BRCA1/2 or MMR genes mutation. Genetic testing and consultations for familial high-risk individuals are exclusively funded and monitored by the INCa in France. All nationwide cancer genetics centers reported annually standardized parameters of activity from 2003 to 2011. The analysis included a total of 240,134 consultations and 134,652 genetic tests enabling to identify 32,494 mutation carriers. Referral for hereditary breast and ovarian cancer (HBOC) or colorectal cancer predisposition syndromes represented 59 % (141,639) and 23.2 % (55,698) consultations, respectively. From 2003 to 2011, we found a dramatic and steady increase of tests performed for BRCA1/2 (from 2,095 to 7,393 tests/year, P < 0.0001) but not for MMR genes (from 1,144 to 1,635/year, P = NS). The overall percentage of deleterious mutations identified in the probands tested was 13.8 and 20.9 % in HBOC and Lynch syndromes, respectively. Pooled analysis for BRCA1/2 and Lynch syndrome tests showed an inverse relationship between the percentage of mutation detected and the absolute number of tests performed over the time (overall Cochran-Armitage test for trend: P < 0.001). In families with BRCA1/2 or MMR identified mutations, there was an average number of 2.94 and 3.28 relatives performing targeted tests, respectively. This nationwide study shows a lack of referral and genetic testing in Lynch as compared to HBOC syndromes. Only a third of relatives of a proband with a predisposing mutation performed a targeted test. Enhanced information about benefit of genetic testing should be given to clinicians and patients for Lynch syndrome and relatives of a proband carrying an identified predisposing mutation.

Nerve cell death in degenerative diseases of the central nervous system: clinical aspects

The origin of degenerative diseases of the central nervous system lies in genetic and acquired disorders. Analysis of the clinical characteristics of diseases affecting specific neuronal systems may help us to understand their pathogenesis. The stereotyped symptomatology characteristic of most degenerative diseases results from neuronal death in specific pathways: pyramidal tract and motor neurons in amyotrophic lateral sclerosis, nigrostriatal dopamine system in Parkinson's disease, posterior and lateral columns of the spinal cord in Friedreich's ataxia, etc. This suggests that these neurons are sensitive to pathological processes that are still unknown. Progression of the disease, whether linear or not, is slow, but it is more rapid than similar effects due to ageing. This indicates either that the environmental cause of degeneration (if it exists) is continuously present or that a vital process has been once and for all disrupted, perhaps at the level of the genome, causing insufficient production of essential proteins, or accumulation of eventually toxic metabolites. Symptoms generally appear during adulthood, i.e. after normal differentiation has taken place, and after a considerable number of neurons have already been damaged. The initiation of neuronal death precedes the appearance of the first symptoms.

The cortical serotonin2 receptors studied with positron-emission tomography and [18F]-setoperone during depressive illness and antidepressant treatment with clomipramine

BACKGROUND

Changes in serotonin (5-HT)2 receptor densities were reported in depression by postmortem studies and following treatment with tricyclic antidepressants in animal studies. Here, 5-HT2 receptors were studied in vivo in depressed patients.

METHODS

Cortical 5-HT2 receptors were investigated prospectively using positron-emission tomography and [18F]-setoperone in 7 depressed patients, before and after at least 3 weeks of clomipramine (CMI), 150 mg daily. They were compared to 7 age-matched controls.

RESULTS

There was no significant difference between the untreated patients and the controls, except in the frontal region, where the [18F]-setoperone specific binding was slightly lower in patients. After CMI treatment, depression scores significantly improved and [18F]-setoperone specific binding decreased in cortical regions, suggesting receptor occupancy and/or receptor regulation, by CMI; however, no clinical score correlated with the 5-HT2 receptor measurements either in the untreated or in the treated conditions.

CONCLUSIONS

These data substantiate the view that tricyclic antidepressants such as clomipramine significantly interact with cortical 5-HT2 serotoninergic receptors in actual therapeutic situations.

No serotonin 5-HT2A receptor density abnormality in the cortex of schizophrenic patients studied with PET

To investigate putative abnormalities of cortical 5-HT2A receptor density in schizophrenia, we used positron emission tomography and [18F]setoperone, a high-affinity 5-HT2A receptor radioligand, in 14 neuroleptic-free or -naive schizophrenic patients and in 15 normal controls. No significant difference between the groups was observed in the whole or regional cortical binding potential of [18F]setoperone, indicating an absence of major 5-HT2A receptor cortical density abnormalities in schizophrenics.

Physostigmine results in an increased decrement in brain glucose consumption in Alzheimer's disease

The responsibility of cerebral cholinergic lesions for the weak clinical response to cholinergic neurotransmission enhancement of Alzheimer's disease (AD) was studied by measuring the effects of physostigmine on glucose consumption and neuropsychological tests. Ten AD and ten aged normals (AN) were examined twice, under placebo and under maximal tolerated dose of physostigmine, in randomized order and blind fashion. Under physostigmine, both groups showed better performances in tests measuring attention (P < 0.05-0.001) but not long-term memory, and cerebral glucose consumption was regionally modified (P < 0.0001). We observed a regional decrease in AD and in AN which was larger in AD, where each patient exhibited a mean metabolic decrease. With normalized values, AD and AN showed a similar decrease in the metabolic values of prefrontal cortex and striatum (P = 0.0003). These findings suggest that cholinergic neurotransmission enhancement depresses glucose consumption and increases selective attention in similar ways in both groups, but to a larger extent in AD. This suggests that brain metabolism in AD over-responds to enhancement of cholinergic neurotransmission. The observed weak response of clinical symptomatology to anticholinesterase agents does not appear to be due to the failure to enhance the activity of the cholinergic system in AD.

Cholinergic neurotransmission has different effects on cerebral glucose consumption and blood flow in young normals, aged normals, and Alzheimer's disease patients

Cerebral blood flow (CBF) and glucose consumption (GC) are both tracers of brain metabolic activity used to image the human brain in vivo. To know if both tracers reacted in the same manner when brain cholinergic neurotransmission was activated, CBF and GC were measured in young normals (YN), aged normals (AN), and Alzheimer's Disease patients (AD) using positron emission tomography (PET), H2 15O, and 18F-FDG. Each subject was studied twice, under placebo and physostigmine, in randomized order and blind fashion using the maximal tolerated dose of physostigmine individually determined. Under physostigmine CBF increased significantly (P = 0.0007) in posterior regions of the cerebral cortex and in the subcortical structures. Inversely, GC was decreased significantly in most regions. The largest decrease was seen in the prefrontal region of the cerebral cortex (P < 0.0001). Significant regional decreases were registered in all three groups of subjects, but were larger in AD than in controls. Looking at the absolute values of prefrontal cortex metabolism we found no correlation (r = 0.04) between the responses of CBF and GC. After normalization of the regional values for the mean we found a significant positive correlation between the responses of CBF and GC (r = 0.71, P < 0.0001). These findings suggest two components in the CBF response to physostigmine: one metabolic, depressive, and regional which follows the GC response; and one vascular, larger, diffuse, and opposite in direction to the metabolic component. These results have implications for the interpretation of CBF values as tracer of brain metabolic activity when brain cholinergic neurotransmission is manipulated.

Evidence for lateral premotor and parietal overactivity in Parkinson's disease during sequential and bimanual movements. A PET study

Patients with Parkinson's disease have great difficulty in performing sequential and bimanual movements. We used H2(15)O PET to study the regional cerebral blood flow associated with performance of sequential finger movements made unimanually and bimanually in a group of Parkinson's disease patients and a group of control volunteers. In controls, sequential finger movements led to activation of the contralateral motor cortex and inferior parietal cortex (Brodmann area 40), the lateral premotor cortex and bilateral supplementary motor area. No prefrontal activation was seen. Sequential finger movements in the Parkinson's disease group were associated with a similar pattern of activation but there was relative impairment of activation in the mesial frontal and prefrontal areas. A novel finding was the presence of relative overactivity in the lateral premotor and inferolateral parietal regions. We conclude that in Parkinson's disease there is a switch from the use of striato-mesial frontal to parietal-lateral premotor circuits in order to facilitate performance of complex finger movements.

Brain energy metabolism in early blind subjects: neural activity in the visual cortex

As an attempt to better understand the metabolic basis for the previously reported increases in glucose metabolism in the visual cortex of congenitally blind subjects, cerebral blood flow, oxygen consumption and glucose utilization were investigated with multitracer positron emission tomography. Measurements were carried out in three subjects who became blind early in life and in three age-matched blindfolded controls. Regional analysis of cerebral blood flow, metabolic rates for oxygen and glucose utilization revealed that these parameters were relatively higher in the visual cortex in case of early blindness (109.7 +/- 2.4%; 114.3 +/- 1.5%; 118.0 +/- 5.5%, respectively) than in controls (98.1 +/- 3.9%; 108.6 +/- 3.6%; 105.2 +/- 4.8%). There were slight differences, albeit statistically not significant, between early blind and control subjects in terms of oxygen-to-glucose metabolic ratios. The relatively preserved stoichiometry in the visual areas of blind subjects points to the lack of variation in the yield of glucose oxidation in this cortex. Those observations suggest that the high level of energy metabolism disclosed in early blind visual cortex is related to neural activity.

Does the enhancement of cholinergic neurotransmission influence brain glucose kinetics and clinical symptomatology in progressive supranuclear palsy?

Cholinergic systems are markedly affected both in cortical and subcortical cerebral areas of patients with progressive supranuclear palsy (PSP). To determine whether it is possible to modify the clinical picture of PSP through the enhancement of brain cholinergic neurotransmission, we studied the effects of physostigmine, an anticholinesterase reference drug, on symptoms and brain glucose metabolism using [18F]fluorodeoxyglucose (FDG) and PET. Patients were evaluated blind in a randomized order with both placebo and physostigmine infusions after an individual determination of maximal tolerated dose. Under steady-state physostigmine infusions, although glucose consumption was not significantly modified, the entry of glucose from blood to brain was regionally increased from 8 to 32% of placebo values suggesting an increase in cerebral blood flow (CBF) or an increase in the activity of brain glucose transporter. Following physostigmine administration in the same patients: the errors in antisaccades during ocular movement testing were significantly reduced, a significant reduction in errors or performance was found in four out of seven neuropsychological tests, and motor disability was not significantly altered. Although the precise pathophysiology of these physostigmine-induced effects needs further investigations, our study suggests that part of the clinical symptomatology in PSP could be relieved by the enhancement of brain cholinergic neurotransmission.

Levodopa-induced dyskinesias are improved by fluoxetine

We evaluated the severity of motor disability and dyskinesias in seven levodopa-responsive patients with Parkinson's disease after an acute challenge with the mixed dopamine agonist, apomorphine, before and after the administration of fluoxetine (20 mg twice per day) for 11 +/- 1 days. After fluoxetine treatment, there was a significant 47% improvement (p < 0.05) of apomorphine-induced dyskinesias without modification of parkinsonian motor disability. The dyskinesias were reduced predominantly in the lower limbs during the onset and disappearance of dystonic dyskinesias (onset- and end-of-dose dyskinesias) and in the upper limbs during choreic mid-dose dyskinesias. The results suggest that increased brain serotoninergic transmission with fluoxetine may reduce levodopa- or dopamine agonist-induced dyskinesias without aggravating parkinsonian motor disability.

The neuropsychological pattern of corticobasal degeneration: comparison with progressive supranuclear palsy and Alzheimer's disease

The pattern of cortical and subcortical neuropathologic lesions in corticobasal degeneration (CBD) should predict a specific cognitive profile in this disease. To characterize this profile and to determine its specificity by comparison with progressive supranuclear palsy (PSP) and senile dementia of the Alzheimer's type (SDAT), we used an extensive neuropsychological battery assessing global efficiency, executive functions, various tests of encoding and retrieval, dynamic motor organization, and upper limb praxis. We compared the performance of patients with CBD (n = 15) with that of controls (n = 19) matched for age and education, and with that of patients with PSP and SDAT (15 in each group), matched for severity of dementia and depression. Patients with CBD showed: (1) a moderate global deterioration; (2) a dysexecutive syndrome similar to that of patients with PSP and more severe than in SDAT; (3) explicit learning deficits, without retention difficulties and easily compensated by using the same semantic cues at encoding and retrieval as in PSP; this was in contrast with SDAT where cued recall and recognition were also impaired; (4) disorders of dynamic motor execution (temporal organization, bimanual coordination, control, and inhibition) similar to those of patients with PSP and not in SDAT; (5) asymmetric praxis disorders (posture imitation, symbolic gesture execution, and object utilization) that were not observed in PSP or SDAT. Patients with CBD show a specific neuropsychological pattern associating a dysexecutive syndrome, likely due to degeneration of the basal ganglia and prefrontal cortex, and asymmetric praxis disorders, which might be related to premotor and parietal lobe lesions. This neuropsychological profile may help to distinguish this condition clinically from other neurodegenerative diseases.

Metabolic effects of scopolamine and physostigmine in human brain measured by positron emission tomography

Two of the more consistent findings in Alzheimer's disease are depressions in frontal and temporoparietal glucose metabolism and a loss of cholinergic neurons in the nucleus basalis of Meynert. Nonetheless, cholinergic replacement strategies have had only minimal therapeutic successes. Whether this situation reflects the limited contribution of cholinergic deafferentation to the intellectual decline or the meager ability of the pharmaceuticals tested to exert their intended pharmacologic action remains unclear. To address this question, the distribution of cerebral abnormalities found in untreated Alzheimer patients, as revealed by positron emission tomography following 18F-fluorodeoxyglucose, were compared with the pattern of functional changes produced by drugs that block or stimulate cholinergic function. Physostigmine was administered to 6 Alzheimer patients to increase brain cholinergic neurotransmission. The anticholinergic scopolamine, given to normal volunteers, was administered to 6 age-matched controls. These data were compared to those obtained from the same subjects while receiving placebo. Amnestic doses of the anticholinergic, scopolamine increased glucose metabolism by up to 20% (p < 0.001) in all brain regions studied, except thalamus. This response contrasted with the metabolic reductions of up to 17% (p < 0.01), especially in parietal and frontal association cortices, occurring in unmedicated Alzheimer patients. Maximum tolerated doses of the anti-cholinesterase, physostigmine, rather than tending to normalize abnormalities in these patients, further reduced cerebral metabolism (p < 0.01) and increased metabolism in thalamus in a pattern inversely correlated (p < 0.001) with that produced by scopolamine. These results fail to support a cholinergic basis for the abnormal metabolic pattern in Alzheimer's disease.

Comparison of cholinergic drug effects on regional brain glucose consumption in rats and humans by means of autoradiography and position emission tomography

Cholinergic mechanisms have been extensively studied in animals and have been implicated in the pathogenesis of human disorders such as Alzheimer's disease. However, few investigations have directly evaluated the validity of extrapolating the results of animal studies to humans. As a component of a continuing examination of the contribution of cholinergic deficits to the alterations in brain metabolism that occur in Alzheimer's disease, we have compared the effects of scopolamine and physostigmine on regional brain energy metabolism in both rats and humans, using a common region of interest atlas. In Alzheimer's patients and in rodents, physostigmine increased glucose metabolism in several regions (e.g. thalamus) and decreased it in others. Overall, there was a significant positive correlation for the effects of physostigmine in the nineteen brain regions studied in both species (r = 0.51, P < 0.05). In normal humans, scopolamine induced a metabolic increase in most brain regions except in the thalamus. Outside this structure, the regional effects of scopolamine were significantly and negatively correlated (r = 0.58, P < 0.01) between rat and human. These results suggest that: (1) cholinergic mechanisms have a similar anatomic distribution in both species, (2) muscarinic receptor-mediated cholinergic effects could predominate outside the thalamus, (3) muscarinic mechanisms are inhibitory in humans but are more complex and possibly excitatory in rats, (4) nicotinic stimulatory effects are found in the thalamus of both species, and (5) physostigmine, but not scopolamine, alters glucose consumption similarly in both species.

Loss of brain 5-HT2 receptors in Alzheimer's disease. In vivo assessment with positron emission tomography and [18F]setoperone

Using [18F]setoperone and positron emission tomography (PET), alterations in serotonergic 5-HT2 receptor binding were studied in cerebral cortex of nine unmedicated patients with probable Alzheimer's disease and 37 healthy controls. The kinetics of unchanged radioligand in plasma and 18F-radioactivity in blood and brain were obtained for 90 min following tracer injection. The specific binding of [18F]setoperone to 5-HT2 receptors in the cerebral cortex was quantitated by subtraction using cerebellum as reference. In controls, a significant reduction in specific binding was associated with age and similar linear regression slopes were obtained in all the cortical regions studied. No significant difference was observed between patients with Alzheimer's disease and age-matched controls in the injected mass of setoperone, percentage of unmetabolized [18F]setoperone in plasma, 18F-radioactivity in blood fractions and cerebellar 18F-radioactivity concentration, indicating similar non-specific brain kinetics and metabolism of the radioligand. In contrast, there was a significant reduction in specific [18F]setoperone binding in the cerebral cortex in patients with Alzheimer's disease relative to control values (temporal, 69%; frontal, 69%; parietal, 55%; temporo-parietal, 54%; occipital cortex, 35%). The results demonstrate that the loss in 5-HT2 receptor binding in the cerebral cortex of patients with Alzheimer's disease, long documented by post-mortem studies, can now be assessed in vivo using PET.

Effects of cholinergic agonists on regional brain energy metabolism in the scopolamine-treated rat

The effects of scopolamine, physostigmine, RS86 and U-80816B on regional energy metabolism were studied in rodents by means of the 2-deoxyglucose autoradiographic technique. Scopolamine depressed metabolism in an area of cerebral cortex, focused around the parietal region. Rats treated with cholinergic direct agonists (U-80816B, RS86) as well as with the indirect agonist (physostigmine) all showed decreases in cortical energy metabolism, similar to scopolamine. They also induced an increase in thalamic metabolism. When these drugs were given in conjunction with scopolamine, metabolism tended to change in the opposite direction from the values obtained with the drug alone. These results suggest that there are complex interactions between pre- and post-synaptic muscarinic receptors. Additionally, nicotinic receptors could also be involved in some of the effects of physostigmine.

Corticobasal degeneration: decreased and asymmetrical glucose consumption as studied with PET

Cerebral energy metabolism was studied by positron emission tomography and [18F]fluorodeoxyglucose in five patients with clinical diagnoses of probable corticobasal degeneration. A reduction in glucose consumption was observed in most cortical and subcortical structures compared to age-matched controls. The reduction was greatest on the side of the brain contralateral to the most affected limbs, as shown by the significantly lower ratios of contralateral to homolateral metabolic rates, in the temporal and sensorimotor cortex of patients compared to controls. A distinct asymmetry between the two hemispheres could be observed in a patient who was examined twice in the course of his illness. Detection of this asymmetrical decrease in brain cortical and subcortical glucose metabolism may prove useful as additional evidence supporting clinical diagnoses of the disease.

Blood-cerebrospinal fluid and blood-brain barriers imaged by 18F-labeled metabolites of 18F-setoperone studied in humans using positron emission tomography

18F-Setoperone, a sensitive radioligand for brain serotonin 5-HT2 receptor positron emission tomography studies, is metabolized into 18F-labeled metabolites, which participate in blood 18F radioactivity. Its main metabolite, identified as reduced 18F-setoperone, was synthesized and studied in humans to determine if 18F-labeled metabolites of 18F-setoperone (a) enter into the brain, (b) bind to the 5-HT2 receptor, and (c) explain the increase of 18F radioactivity in the free fraction in blood measured following 18F-setoperone injection. After reduced 18F-setoperone injection, the brain-to-blood 18F radioactivity concentration ratio (a) was low, at the beginning, indicating that this metabolite did not cross the blood-brain barrier; (b) was increased thereafter, with a higher radioactivity level in the choroid plexus than in brain tissue, suggesting a blood-CSF barrier crossing due to radioligand hydrophilicity; and (c) showed similar kinetics for cerebellum and frontal cortex, indicating that radioactive metabolites of 18F-setoperone did not bind to the 5-HT2 receptor. Because hydrophilic 18F-labeled metabolites of 18F-setoperone increased 18F radioactivity in the free fraction in blood, we quantified the relation between 18F-setoperone metabolism and free fraction kinetics in blood. A significant negative correlation was found between metabolism and free fraction rate constants in blood, showing it was possible to predict the 18F-setoperone metabolism rate using free fraction kinetics in blood. This will allow us to avoid the use of radio-TLC, a reference method that is difficult to use when multiple samples must be analyzed. A hydrophilic positron-emitter radioligand could also be used to study the blood-CSF barrier.

Decreased cerebral glucose utilization in myotonic dystrophy

To test the hypothesis that cerebral metabolism is altered in myotonic dystrophy (MyD), we investigated cerebral glucose kinetics and utilization in 11 adult patients with MyD and 14 healthy controls, using 18F-labeled 2-fluoro-2-deoxy-D-glucose (FDG) and dynamic positron emission tomography. Estimation of rate constants in MyD revealed a reduction of FDG delivery to the brain. Cortical glucose utilization rate was reduced by about 20% in MyD. These findings may be related to the presence of neurologic impairment in MyD and prompt further investigations on the metabolic and clinical features of brain dysfunction in this disease.

Regional cerebral glucose metabolism compared in rodents and humans

In order to compare regional brain glucose metabolism in rats and humans, this parameter was measured using Sokoloff's deoxyglucose method in rats, and positron emission tomography with magnetic resonance imaging in humans. An atlas of cerebral regions of interest common to both species was developed to facilitate the evaluation of the relationship in regional values. We found among the regions studied a significant positive correlation in their metabolic values (r = 0.72, P less than 0.001) and coefficients of variation (r = 0.59, P less than 0.01) suggesting that regional brain glucose consumption is comparable between rat and human. Results of this study support the view that rat and human brain may be phylogenetically linked functionally as well as anatomically.

Somatostatin replacement therapy for Alzheimer dementia

Somatostatin is consistently diminished in brains of patients with Alzheimer's disease. To evaluate whether pharmacological restoration of this transmitter deficit has therapeutic value, the synthetic analogue octreotide was administered intravenously to 14 Alzheimer patients under double-blind, placebo-controlled conditions. At the highest dose administered, spinal fluid concentrations approximated those found in brains of experimental animals receiving behaviorally effective amounts of the drug. Neuropsychological testing, however, showed no clinically significant improvement. Coadministration of octreotide and physostigmine to 1 patient also failed to improve cognition. Positron emission tomographic studies in 6 patients revealed a generalized decrease in glucose metabolism as a result of octreotide infusion. These findings suggest that stimulation of the somatostatin system has no value in the symptomatic treatment of Alzheimer dementia.

Does ageing aggravate parkinsonian disability?

The influence of age of onset of Parkinson's disease on the severity and the pattern of motor symptoms was investigated by comparing the motor scores with and without levodopa therapy in two groups of patients divided according to age of onset (early less than 50, late greater than 60 years) and matched for disease duration (n = 69 in each group, Study I). The baseline score, that is, the motor disability of patients when off levodopa, was similar in the early- and late- onset groups. In contrast, the residual motor score, assessed when the effect of levodopa treatment was maximum and stable, was significantly higher in the late onset group. When the two groups of patients were matched, in addition, for their residual motor score, (n = 54 in each group, Study II), no difference was observed between the early and late onset groups, except for gait disorder which was more severe in older patients. These results suggest that age of onset mainly affects the response to levodopa therapy, because it may increase the prevalence of non-dopaminergic lesions of the brain, including those responsible for gait disorders.

PET studies of cortical diaschisis in patients with motor hemi-neglect

Six patients presenting with multimodal, predominantly motor hemi-neglect, were investigated by 15O2 or 18F-DG and PET to study the local cerebral metabolism in intact regions. All had suffered from an acute right-sided (n = 5) or left-sided (n = 1) focal hemispheric lesion (cortico-subcortical and purely subcortical in three patients each). Frontal and parietal cortices on the side of the lesion were significantly hypometabolic relative to the other side in each case, presumably as a result of diaschisis, whereas thalamic hypometabolism was significant in only 4 patients. Compared to absolute metabolic rates for controls, the uninjured hemisphere showed a trend towards hypometabolism. Hence, true hyperactivity of the contralateral hemisphere with respect to the ipsilateral cerebral cortex was not associated with motor hemineglect in this series. On the contrary, hemineglect was associated with a widespread hypometabolism of the entire ipsilateral cerebral cortex in the context of a moderately reduced metabolism of the ipsilateral thalamus and contralateral cerebral cortex. These findings are consistent with the implication of a cortico-subcortical network serving attention.

Nootropic drugs in Alzheimer's disease: symptomatic treatment with pramiracetam

The cognitive-enhancing effects of pramiracetam in animal models of learning and memory are characterized by an inverted U-shaped dose-response curve. We evaluated antidementia efficacy of this drug in 10 patients with probable Alzheimer's disease employing a 2-phase, placebo-controlled, enrichment-type trial design. Eight patients evidenced a best dose in the dose-finding phase, but in the subsequent replication phase only two again improved to a similar degree. PETs with fluorodeoxyglucose obtained in two individuals showed no definite change. Doses up to 4,000 mg pramiracetam are unlikely to confer symptomatic benefit to Alzheimer's disease patients.

PET studies of [18F]methyl-MK-801, a potential NMDA receptor complex radioligand

Using positron emission tomography (PET), the potential of 18F-labelled fluoro-methyl-MK-801([18F]FMM) as a radioligand for in vivo studies of the NMDA receptor complex was investigated in baboons. In baseline conditions, there was a slight differential retention of [18F]FMM in cerebral cortex and striatum relative to cerebellum, compatible with specific binding. However, neither pretreatment with pharmacological doses of MK-801 or phencyclidine, nor severe, transient brain hypoxia, were able to clearly alter [18]FMM brain regional kinetics, indicating limited usefulness of this radioligand for in vivo PET investigations of the NMDA receptor.

Positron emission tomography study in progressive supranuclear palsy. Brain hypometabolic pattern and clinicometabolic correlations

In 41 patients with progressive supranuclear palsy (PSP) that was diagnosed on the basis of eight clinical criteria (25 patients with all eight criteria [probable PSP] and 16 with six or seven criteria [possible PSP]), we studied cerebral energy metabolism by using positron emission tomography and the fludeoxyglucose F 18 or the oxygen 15 method. Compared with age-matched controls, each of the cortical and subcortical metabolic values was significantly reduced, with a predominance in the frontal cortex, in both groups of patients with probable and possible PSP, without a difference between these two groups, suggesting similar underlying disease. The frontal metabolic value decreased with disease duration, but the relative frontal hypometabolism (expressed as the fronto-occipital metabolic ratio) was apparently already present in the early stages of the disease. The parkinsonian motor score was correlated with the caudate and thalamic metabolic values. The intellectual deterioration index was significantly correlated with both the frontal and the nonfrontal metabolic values. Finally, the frontal neuropsychological score was significantly correlated with only the fronto-occipital metabolic ratio. Hence, in PSP, a degenerative brain disease with subcortical lesions, the prominent frontal lobe-like syndrome essentially depends on the relative hypometabolism of the frontal cortex.

A method for the in vivo investigation of the serotonergic 5-HT2 receptors in the human cerebral cortex using positron emission tomography and 18F-labeled setoperone

Following previous validation in baboons, we have studied the characteristics of [18F]setoperone as a radioligand for investigating serotonergic 5-hydroxytryptamine2 (5-HT2) receptors in the normal, unmedicated human brain with positron emission tomography (PET); subjects orally pretreated with therapeutic amounts of ketanserin, sulpiride, or prazosin were also studied to evaluate the specificity and sensitivity of [18F]setoperone brain specific binding. In controls (n = 10), the tracer showed a clear-cut retention in both frontal cortex and striatum (known to contain a high density of 5-HT2 receptors) relative to cerebellum (known to be devoid of 5-HT2 receptors). In the seven young controls (20-39 years old), the frontal cortex/cerebellum and striatum/cerebellum ratios increased during the first hour to reach similar values of 2.53 +/- 0.12 and 2.38 +/- 0.11 (mean +/- SEM), respectively, and were essentially stable during the second hour. Pretreatment with ketanserin (a 5-HT2 blocker) significantly reduced the frontal cortex/cerebellum ratio to 0.7-1.0 at 65 min, whereas the striatum/cerebellum ratio was significantly, but only partially, reduced. During sulpiride treatment (a D2 blocker), the frontal cortex/cerebellum ratio was not altered, whereas the striatum/cerebellum ratio was significantly, but only partially, reduced. With prazosin pretreatment (an alpha 1-adrenergic blocker), neither the frontal cortex/cerebellum nor the striatum/cerebellum ratio was modified. These data in humans with PET demonstrate that [18F]setoperone labels with high sensitivity and selectivity 5-HT2 receptors in the frontal cortex; in striata, however, binding is to both 5-HT2 and D2 receptors. The deproteinated-to-whole plasma radio-activity concentration ratio increased with time following injection. The mean percentage of intact [18F]setoperone, in deproteinated plasma, was 82, 74, 53, 45, 30, and 22% at 5, 10, 20, 30, 60, and 110 min following injection, respectively. These data indicate that [18F]setoperone (a) is significantly bound to plasma proteins and (b) is significantly metabolized into several labeled metabolites that are much more hydrophilic than setoperone and, hence, presumably do not cross the blood-brain barrier. These results suggest the suitability of [18F]setoperone data for modeling of 5-HT2 receptor binding in brain.

Striatal dopamine D2 receptors in tardive dyskinesia: PET study

The dopamine D2 receptors were investigated in vivo in eight neuroleptic-free patients with persistent tardive dyskinesia using positron emission tomography and 76Br-bromospiperone. The striatal receptor density, estimated by the striatum/cerebellum radioligand concentration ratio, was not elevated in patients as compared with age-matched controls but was positively correlated with the severity of orofacial dyskinesia assessed with the Abnormal Involuntary Movement Rating Scale. These results indicate that tardive dyskinesia is associated with normal levels of striatal D2 receptors but the severity of orofacial movements may depend on the relative density of striatal D2 receptors.

Striatal dopamine receptor occupancy during and following withdrawal from neuroleptic treatment: correlative evaluation by positron emission tomography and plasma prolactin levels

The percentage occupation of striatal dopamine D2 receptors has been evaluated in 25 patients using 76Br-bromospiperone positron emission tomography (PET) and prolactin plasma levels (PRL) during oral neuroleptic treatment (11 studies), 1-90 days following discontinuation of such treatment (16 studies), and 1-120 days after last intramuscular administration of depot neuroleptics (nine studies). The PET-estimated occupation was highly significantly correlated in a sigmoid-like fashion to the logarithm of the chlorpromazine-equivalent dose of oral neuroleptics (suggesting a strict dose-occupation relationship during oral neuroleptic treatment and supporting the D2-mediated hypothesis of neuroleptic action), while PRL was weakly related to daily dosage. Following withdrawal, return to normal receptor availability, as estimated by PET, occurred within 5-15 days (suggesting that protracted effects of neuroleptics after withdrawal are not due to sustained D2 receptor occupation), but PRL values fell even more rapidly. Efficient treatment with depot neuroleptics resulted in marked PET-estimated D2 receptor occupation, stable over the whole 4-week drug-administration interval, suggesting that longer intervals could be appropriate; PRL values bore no relationship to PET-estimated occupation, indicating variable intersubject tolerance to neuro-endocrine dopamine blockade. Overall, PET was much more sensitive than PRL to estimate striatal D2 receptor occupation in vivo.

D1 and D2-type dopamine receptors in patients with Parkinson's disease and progressive supranuclear palsy

The densities of D1- and D2-type dopamine receptors were measured with [3H]SCH23390 and [3H]spiperone, in the caudate nucleus and putamen of a large series of patients with Parkinson's disease or progressive supranuclear palsy, in relation to markers of dopaminergic and cholinergic innervation of the striatum ([3H]dihydrotetrabenazine binding and choline acetyltransferase activity). Correlations were sought between these parameters and clinical characteristics of the patients (abnormal involuntary movements, dementia, confusional syndrome or treatment). In Parkinson's disease, the densities of both types of receptors were unchanged, whereas in PSP, the density of D2, but not D1-type dopamine receptors, was decreased in the caudate nucleus and the putamen. No correlations between the biochemical and clinical data were found.

Does levodopa aggravate Parkinson's disease?

We studied the possible deleterious effect of levodopa therapy on 185 patients with Parkinson's disease and concluded that the time when levodopa is introduced, the daily dose, and the duration of treatment do not aggravate Parkinson's disease. We also studied 72 parkinsonian patients with levodopa-induced abnormal involuntary movements to see whether early initiation of levodopa therapy affected the time of onset of abnormal involuntary movements. The results suggested that it did not, and that levodopa was started early in these patients because of the severity of their motor disability.

[18F]setoperone: a new high-affinity ligand for positron emission tomography study of the serotonin-2 receptors in baboon brain in vivo

The potential usefulness of 18F-labelled setoperone, a high-affinity antagonist of the serotonin-2 (S2) receptors, to study the S2 receptors in vivo with positron emission tomography (PET) was investigated in four baboons. In the control state, there was a rapid wash-out of intravenously injected tracer from the cerebellum, a structure essentially devoid of S2, receptors, and marked retention in both the cerebral cortex and the striatum (region/cerebellum ratios up to 3 and 3.5 after 60 min in cortex and striatum, respectively). The retention of radioligand in the cerebral cortex was abolished after pretreatment with spiperone or ketanserin at saturating doses. In striatum, however, radioligand retention was fully prevented by spiperone but only partly by ketanserin. These results demonstrate that [18F]setoperone was bound to the S2 receptors in the cerebral cortex, whereas the radioligand was bound to both the S2 and the dopamine D2 receptors in the striatum. The high cortex/cerebellum ratio achieved indicates that [18F]setoperone should be a useful radiotracer for PET studies of the S2 receptors.