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P Lantos

Publications and source records attributed to P Lantos.

At least 19 recordsLinked to original sources
PubMed2005

Radiation doses potentially received on-board aeroplanes during recent solar particle events.

Because the doses received on-board aeroplanes are now monitored to fulfil legal requirements in some countries, including the European Community, the models to calculate doses received during solar events have left their purely academic status to become a part of operational systems as well. The present work considers parameters of importance to determine the doses received during solar events: spectral characteristics of the solar particles and anisotropy of primary particles and their variations in the course of the Ground Level Enhancement (GLE). Precise determination of both, using all the information available from the worldwide neutron monitor network, being a long process, simpler methods are proposed to calculate rigidity spectrum exponent and to correct the models for anisotropy. A recent GLE of large intensity, having occurred on 20 January 2005, is used both as an example of an important event and because the necessary data were collected within a few days, showing that the above methods, in addition to their own interest, have also an operational potential.

Aircraft↗
PubMed2005

Forbush decrease effects on radiation dose received on-board aeroplanes.

Doses received on-board aeroplanes during deep Forbush decreases (FDs) have been recently measured and published. Using an operational model of dose calculation, the effects on aviation dose of the FDs observed from 1981 to 2003 using neutron monitors are studied and a simplified method to estimate dose variations from galactic cosmic ray variations during FDs is derived.

Aerospace Medicine↗
PubMed2003

Phenotypic variability in the brains of a family with a prion disease characterized by a 144-base pair insertion in the prion protein gene.

The use of prion protein (PrP) immunohistochemistry in neuropathology has allowed identification of prion diseases with otherwise atypical histological features. The brains from family members with familial prion diseases can show marked histological variation. A histological and immunohistochemical study was performed on 10 brains of patients with a familial prion disease caused by a 144-base pair (bp) insertion in the prion protein gene. The histology from the cases showed variability in the severity of spongiform change and astrocytosis in both the cerebellum and the cerebrum. There was also variability in the density of microglial cells. The PrP immunohistochemistry revealed that in nine cases there was a similar patch-like deposition of PrP within the molecular layer of the cerebellum. Although in the cerebellum there did seem to be some correlation between the severity of spongiform change, astrocytosis and the density of microglial cells, there was no such correlation between any of these three parameters and the density of PrP staining. There was deposition of beta-amyloid precursor protein (beta-APP) in the cerebellum, suggesting that disrupted axonal transport had a possible role in the evolution of the disease. The cases illustrate the histological variability that can occur in familial prion diseases despite similarity in PrP staining. They also reveal that the relationship between PrP deposition and cerebral or cerebellar damage might be complex.

Adult↗
PubMed2003

History of the solar particle event radiation doses on-board aeroplanes using a semi-empirical model and Concorde measurements.

Measurements during solar particle events with dosemeters flying permanently on-board Concorde are used to develop a semi-empirical model, called SiGLE. The model is intended to calculate, for a given flight plan, the dose equivalent received during a solar particle event observed with ground-based neutron monitors. It is successfully in operation in the SIEVERT computerised system intended to improve monitoring of radiation dose received by aircrews, in application to a European Directive. The semi-empirical model is applied to evaluate, for most exposed routes, the radiation doses corresponding to the GLEs observed since 1942 with ion chambers or neutron monitors. The results for the largest GLEs observed in the past are discussed in terms of radiation risk, and guidelines are suggested concerning possible alerts to the aeroplanes in case of events of exceptional magnitude.

Aircraft↗
PubMed2002

Clinical features of frontotemporal dementia due to the intronic tau 10(+16) mutation.

OBJECTIVE: To describe the clinical features of nine British families with neuropathologically verified frontotemporal dementia (FTD) due to the intronic tau exon 10(+16) mutation. METHODS: Retrospective chart reviews of family members with FTD belonging to nine tau 10(+16) mutation pedigrees in whom neuropathologic examination had been carried out. APOE genotype was determined for those patients for whom DNA was available. RESULTS: The median age at onset was 50 years (range 37 to 59 years; n = 30). The median age at death was 61 years (range 42 to 72 years; n = 33). The median duration of the disease was 11 years (range 3 to 22 years; n = 25) for those who have died and is 17 years (range 15 to 23 years; n = 3) for those living. The most common presenting symptom was disinhibition (n = 23). A minority presented with frontal dysexecutive symptoms, apathy, impairment of episodic memory, or depression. All of these patients subsequently developed personality and behavioral change. Memory impairment, language deficits, ritualistic behavior, hyperphagia, and hyperorality were frequent symptoms. Parkinsonism, neuroleptic sensitivity, or primitive reflexes were present in half of the patients, where these data were available. The clinical features of ALS were absent. Neuropathologic examination of 12 patients demonstrated the hallmark tau-positive neuronal and glial inclusions. APOE genotype did not account for the considerable variation in age at onset, age at death, duration of disease, or severity of estimated brain atrophy. CONCLUSIONS: All cases fulfilled the clinical criteria for a diagnosis of FTD. Despite similar clinical phenotypes, there was considerable variation in age at onset and duration of disease both between and within families, suggesting the presence of an effect due to other genetic or environmental factors.

Adult↗
PubMed2001

The genetic and pathological classification of familial frontotemporal dementia.

BACKGROUND: Frontotemporal dementia (FTD) is an important cause of neurodegenerative dementia, particularly in younger patients. TAU has been identified as the gene responsible for FTD linked to chromosome 17, but it is likely that there is pathological and genetic heterogeneity among families with FTD. OBJECTIVE: To explore the genetic and pathological basis of familial FTD. DESIGN: Clinical case series with genetic analysis of each family, and pathological confirmation of diagnosis where possible. SETTING: Specialist dementia research group, particularly recruiting patients with young-onset dementia. PATIENTS: Twenty-two families with an index member with FTD, meeting Lund-Manchester criteria, and a family history of other affected members with dementia were ascertained. RESULTS: Half of the families had mutations in the TAU gene (TAU exon 10 +14, +16, and P301S), and pathological diagnoses were available in 17 of 22 families. Three main pathological diagnoses were made: FTD with neuronal and glial tau deposition, FTD with ubiquitin inclusions, and FTD with neuronal loss and spongiosis but without intracellular inclusions. No cases of familial Pick disease were identified. With the use of the pathological diagnoses, each family with FTD with neuronal and glial tau deposition had a TAU mutation, whereas TAU mutations were not identified in families in the other 2 diagnostic groups. CONCLUSIONS: This study illustrates the value of TAU sequencing in FTD and suggests that around one half of individuals with familial FTD have TAU mutations and dementia with tau pathological findings. Furthermore, these data suggest that there are at least 2 additional genes to be identified among families with autosomal dominant FTD.

Adult↗
PubMed2001

[Mid-face distraction after LeFort III osteotomy in craniofacial dysmorphism].

BACKGROUND: The success of LeFort III-osteotomy with concurrent advancement of the midface in cases of severe, midfacial hypoplasia is limited by the soft covering tissue of the facial skeleton. There appear to be significant advantages in using distraction osteogenesis of the midface after surgery. CASE REPORT: We discuss the use of an extraoral distraction device after the osteotomy of a 10-year-old girl with Crouzon's disease. and the use of an internal device for a 6-year-old boy with severe midface hypoplasia following Apert's syndrome. RESULTS: In both patients a significant improvement of function, as well as harmonisation of the facial proportions, could be observed and the preoperatively planned distances of midface advancement of 18 and 15 mm respectively could be achieved. DISCUSSION: Distraction osteogenesis is an established procedure for the treatment of mandibular hypoplasia but few reports dealing with complex midface distraction are available outside of the specialist English language literature. We report on both external and internal distraction techniques with which good functional and aesthetic results were achieved.

Acrocephalosyndactylia↗
PubMed2001

Visual hallucinations are associated with lower alpha bungarotoxin binding in dementia with Lewy bodies.

Patients with dementia with Lewy bodies (DLB) commonly experience psychotic symptoms, most notably visual hallucinations. Previously, it has been shown that visual hallucinations in DLB are associated with reduced cortical choline acetyltransferase activity, a marker of cholinergic innervation, but not with predominantly postsynaptic muscarinic M1 receptor binding. In the present investigation, nicotinic acetylcholine receptor (nAChR) levels in the temporal cortex (Brodmann's areas [BA] 20 and 36) were measured in a group of 24 prospectively assessed DLB patients; comparisons were made between groups with or without visual and auditory hallucinations and delusional misidentification. Visual hallucinations and delusional misidentification were associated with lower [(125)I]alpha bungarotoxin binding in areas 36 and 20 (P<.05), but not with changes in [(3)H]epibatidine binding. There were no significant associations with auditory hallucinations. [(3)H]epibatidine, but not [(125)I]alpha bungarotoxin, binding for all DLB cases was reduced compared to controls (P<.001). Loss of cortical alpha 7 nicotinic receptors may contribute to hallucinations and delusional misidentification in DLB, with implications for treatment and understanding the mechanisms of psychotic symptoms in dementia.

Aged↗
PubMed2000

A medical research council randomized trial in patients with primary cerebral non-Hodgkin lymphoma: cerebral radiotherapy with and without cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy.

BACKGROUND: The role of chemotherapy in the treatment of patients with primary central nervous system lymphoma (PCL) remains unclear, with no randomized trials available to aid in the interpretation of the current data. The Medical Research Council therefore conducted the current randomized trial to assess the impact on survival of postradiotherapy chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in nonimmunocompromised adult patients with pathologically proven PCL. METHODS: After surgery, patients were randomized at a ratio of 1:2 to radiotherapy alone (RT: 40 grays [Gy] in 20 fractions to the whole brain followed by a 14-Gy boost to the tumor plus a 2-cm tumor margin) or to the same radiotherapy followed by six cycles of CHOP chemotherapy given at 3-week intervals (RT-CHOP). The target sample size was 90 patients, which allowed 90% power to detect a doubling of the median survival time. RESULTS: Between 1988 and 1995, 53 patients were randomized: Fifteen patients were randomized to RT, and 38 patients were randomized to RT-CHOP. The trial closed earlier than planned through poor accrual. The median patient age was 57 years, 57% of the patients were male, and 75% of the patients had unifocal disease. The median number of chemotherapy cycles received was 6 (mean, 4 cycles). Forty-three patients have died, and the median follow-up of survivors is 5 years (range, 1-9 years). There was no evidence of a benefit from RT-CHOP with respect to overall survival (hazard ratio [HR], 1.19; 95% confidence interval, 0.51-2.76) after adjustment for prognostic factors (patient age and neurologic performance status) in an analysis in which HR > 1 favored the control (RT) group. CONCLUSIONS: CHOP has no clear role in the postradiotherapy treatment of patients with PCL. Chemotherapy is poorly tolerated and largely palliative in older, less fit patients. In younger patients, initial chemotherapy designed to penetrate the blood-brain barrier warrants further investigation.

Adult↗
PubMed1999

Progressive frontal gait disturbance with atypical Alzheimer's disease and corticobasal degeneration.

OBJECTIVES: The clinical neuropsychological, neuroradiological, and neuropathological description of two patients presenting with a frontal gait disturbance. METHODS: Clinical case note review, neuropsychological assessment, functional imaging with (15)O(2) and (18)F-fluorodopa PET, and neuropathology. RESULTS: Both patients presented with frontal gait impairment and only later developed more widespread cognitive impairment. In both cases (15)O(2) PET disclosed focal hypometabolism in the medial frontal lobes and in one patient (18)F-fluorodopa uptake into the caudate and putamen was normal. The neuropathological examination in one patient showed Alzheimer's histopathology together with large swollen eosinophilic neurons characteristic of corticobasal degeneration, which were particularly prominent in the medial frontal lobes. CONCLUSION: Focal degeneration of the medial frontal lobes may present as an isolated gait disturbance and should be considered in the differential diagnosis of patients who present without an obvious structural abnormality on neuroimaging.

Aged↗
PubMed1999

Psychiatric morbidity in dementia with Lewy bodies: a prospective clinical and neuropathological comparative study with Alzheimer's disease.

OBJECTIVE: The literature reports considerable variation in the rates of psychiatric morbidity for patients with dementia with Lewy bodies. The authors intended to clarify the frequency of psychiatric morbidity in dementia with Lewy bodies and how it differs from probable Alzheimer's disease. METHOD: The study incorporated two groups--a clinical case register cohort (98 with dementia with Lewy bodies; 92 with Alzheimer's disease) and 80 (40 with dementia with Lewy bodies: 40 with Alzheimer's disease) prospectively studied, neuropathologically confirmed cases. Diagnoses were made by using the McKeith et al. consensus criteria for dementia with Lewy bodies and the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria for Alzheimer's disease. Neuropathological diagnoses were made by using the consensus criteria for dementia with Lewy bodies and the Mirra et al. protocol for Alzheimer's disease. RESULTS: The occurrence of psychiatric symptoms was reported over 1 month. Hallucinations, depression, delusions, and delusional misidentification were all significantly higher for patients with dementia with Lewy bodies. The differences in frequency between dementia with Lewy bodies and Alzheimer's disease for auditory and visual hallucinations were especially pronounced for patients with mild cognitive impairment. The presence of psychiatric symptoms at presentation was a better discriminator between dementia with Lewy bodies and Alzheimer's disease than occurrence over the course of dementia. CONCLUSIONS: Delusional misidentification and hallucinations in the early stages of dementia may improve differentiation between patients with dementia with Lewy bodies and those with Alzheimer's disease and have important treatment implications.

Aged↗
PubMed1999

Validity of current clinical criteria for Alzheimer's disease, vascular dementia and dementia with Lewy bodies.

BACKGROUND: Following the success of the NINCDS-ADRDA criteria for Alzheimer's disease, groups interested in vascular dementia and dementia with Lewy bodies have now adopted similar criteria. AIMS: To assess whether the validity of these criteria are influenced by the prevalence of mixed pathologies or by the prevalence rate. METHOD: A community based post-mortem study. RESULTS: Mixed pathologies were common (33.8%). The high specificities obtained for the CDLB and NINDS-AIREN criteria (1.00 and 0.95, respectively) were associated with low sensitivities (0.22 and 0.43, respectively). Low prevalence and the presence of mixed pathologies had a deleterious effect on positive predictive values. CONCLUSIONS: Current clinical diagnostic criteria are good at detecting pathology per se but not at detecting pure pathology. A large proportion of subjects from the general population fulfilling probable CDLB, probable NINCDS-ADRDA or probable NINDS-AIREN will have mixed pathologies.

Adult↗
PubMed1999

[Consensus on the diagnosis of multi-system atrophy].

We report the results of a consensus conference on the diagnosis of multiple system atrophy. We describe the clinical features of the disease, which include four domains: autonomic failure/urinary dysfunction, parkinsonism and cerebellar ataxia, and corticospinal dysfunction. We set criteria to define the relative importance of these features. The diagnosis of possible multiple system atrophy requires one criterion plus two features from separate domains. The diagnosis of probable multiple system atrophy requires the criterion for autonomic failure/urinary dysfunction plus poor levodopa responsive parkinsonism or cerebellar ataxia. The diagnosis of definite multiple system atrophy requires pathological confirmation.

Diagnosis, Differential↗
PubMed1998

Consensus statement on the diagnosis of multiple system atrophy. American Autonomic Society and American Academy of Neurology.

We report the results of a consensus conference on the diagnosis of multiple system atrophy (MSA). We describe the clinical features of the disease, which include four domains: autonomic failure/urinary dysfunction, parkinsonism and cerebellar ataxia, and corticospinal dysfunction. We set criteria to define the relative importance of these features. The diagnosis of possible MSA requires one criterion plus two features from separate domains. The diagnosis of probable MSA requires the criterion for autonomic failure/urinary dysfunction plus poor levodopa responsive parkinsonism or cerebellar ataxia. The diagnosis of definite MSA requires pathological confirmation.

Antiparkinson Agents↗
PubMed1998

A clinicopathological study of autism.

A neuropathological study of autism was established and brain tissue examined from six mentally handicapped subjects with autism. Clinical and educational records were obtained and standardized diagnostic interviews conducted with the parents of cases not seen before death. Four of the six brains were megalencephalic, and areas of cortical abnormality were identified in four cases. There were also developmental abnormalities of the brainstem, particularly of the inferior olives. Purkinje cell number was reduced in all the adult cases, and this reduction was sometimes accompanied by gliosis. The findings do not support previous claims of localized neurodevelopmental abnormalities. They do point to the likely involvement of the cerebral cortex in autism.

Adult↗
PubMed1996

Neuropathology of early HIV-1 infection.

Early HIV-1 invasion of the central nervous system has been demonstrated by many cerebrospinal fluid studies; however, most HIV-1 carriers remain neurologically unimpaired during the so called "asymptomatic" period lasting from seroconversion to symptomatic AIDS. Therefore, neuropathological studies in the early pre-AIDS stages are very few, and the natural history of central nervous system changes in HIV-1 infection remains poorly understood. Examination of brains of asymptomatic HIV-1 positive individuals who died accidentally and of rare cases with acute fatal encephalopathy revealing HIV infection, and comparison with experimental simian immunodeficiency virus and feline immunodeficiency virus infections suggest that, invasion of the CNS by HIV-1 occurs at the time of primary infection and induces an immunological process in the central nervous system. This includes an inflammatory T-cell reaction with vasculitis and leptomeningitis, and immune activation of brain parenchyma with increased number of microglial cells, upregulation of major histocompatibility complex class II antigens and local production of cytokines. Myelin pallor and gliosis of the white matter are usually found and are likely to be the consequence of opening of the blood brain barrier due to vasculitis; direct damage to oligodendrocytes by cytokines may also interfere. These white matter changes may explain, at least partly, the early cerebral atrophy observed, by magnetic resonance imaging, in asymptomatic HIV-1 carriers. In contrast, cortical damage seems to be a late event in the course of HIV-1 infection. There is no significant neuronal loss at the early stages of the disease, no accompanying increase in glial fibrillary acid protein staining in the cortex, and only exceptional neuronal apoptosis. Although HIV-1 proviral DNA may be demonstrated in a number of brains, viral replication remains very low during the asymptomatic stage of HIV-1 infection. This makes it likely that, although opening of the blood brain barrier may facilitate viral entry into the brain, specific immune responses including both neutralising antibodies and cytotoxic T-lymphocytes, continuously inhibits viral replication at that stage.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Neuronal pattern correlates with the severity of human immunodeficiency virus-associated dementia complex. Usefulness of spatial pattern analysis in clinicopathological studies.

The spatial distributional pattern of neurons, in the superior frontal gyrus of 32 subjects who died of acquired immune deficiency syndrome, was examined. The patients were classified as nondemented, mildly demented, and severely demented, and some were treated with the anti-retroviral drug zidovudine. Spatial statistical techniques were employed to investigate the degree of clustering in the individual cases and various groups. We found that the cluster pattern of large and small neurons differed significantly with increasing severity of dementia but was not influenced by the duration of zidovudine treatment. We conclude that this is a sensitive technique for clinicopathological correlations and that the differences may result from loss of specific neuronal populations, which could determine the degree of dementia.

AIDS Dementia Complex↗