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A Loasses

Publications and source records attributed to A Loasses.

At least 19 recordsLinked to original sources
PubMed2000

The role of proton therapy in the treatment of large irradiation volumes: a comparative planning study of pancreatic and biliary tumors.

PURPOSE: The purpose of this study was to examine the potential benefit of proton therapy for abdominal tumors. Extensive comparative planning was conducted investigating the most up-to-date photon and proton irradiation technologies. METHODS AND MATERIALS: A number of rival plans were generated for four patients: two inoperable pancreatic tumors, one inoperable and one postoperative biliary duct tumor. The dose prescription goal for these large targets was 50 Gy, followed by a boost dose up to 20 Gy to a smaller planning target volume (PTV). Photon plans were developed using "forward" planning of coplanar and noncoplanar conformal fields and "inverse" planning of intensity-modulated (IM) fields. Proton planning was simulated as administered using the so called spot-scanning technique. Plans were evaluated on the basis of normal tissues' dose-volume constraints (Emami B, Lyman J, Brown A, et al. Tolerance of normal tissue to therapeutic irradiation. Int J Radiat Oncol Biol Phys 1990;21:109-122) and coverage of treatment volumes with prescribed doses. RESULTS: For all cases, none of the forward calculated photon plans was able to deliver 50 Gy to large PTVs at the same time respecting the dose-volume constraints on all critical organs. Nine evenly spaced IM fields achieved or nearly achieved all maximum dose constraints to critical structures for two out of three inoperable patients. IM plans also obtained good results for the postoperative patient, even though the dose to the liver was very close to the maximum allowed. In all cases, photon irradiation of large PTV1s to 50 Gy followed by a 20 Gy boost entailed a risk very close to or higher than 5% for serious complications to the kidneys, liver, or bowel. Simple arrangements of 2, 3, and 4 proton fields obtained better dose conformation to the target, allowing the delivery of planned doses including the boost to all patients, without excessive risk of morbidity. Dose homogeneity inside the targets was also superior with protons. CONCLUSION: For the irradiation of large PTVs located in the abdominal cavity, where multiple, parallel structured organs surround the target volumes, proton therapy, delivered with a sophisticated isocentric technique, has the potential to achieve superior dose distributions compared with state-of-the-art photon irradiation techniques. IM photon plans obtain better results in the postoperative case, because the reduced volume lessens the effect of the unavoidable increase of integral dose to surrounding tissues.

Algorithms↗
PubMed2000

Deficient intentional access to semantic knowledge in patients with severe closed-head injury.

Patients after severe closed-head injury (CHI) demonstrate reduced ability to spontaneously utilize semantic memory during word-list memory tests and when requested to answer questions regarding general knowledge. However, they show normal lexical facilitation in both automatic and intentional semantic priming paradigms. The present study was aimed at investigating two alternative hypotheses a) that the deficit in semantic processing after CHI is the result of impaired access to an otherwise normal semantic system or b) that it reflects a loss of knowledge from a deteriorated semantic store. For this purpose, the performance of 15 CHI patients on an automatic Semantic Priming paradigm and on tests of Picture Naming and Semantic Judgment were compared to those of 14 normal controls (NC). Although CHI patients' reaction times were significantly slower than those of NCs, the semantic priming effect was comparable in the two groups. Instead, CHI patients performed significantly worse than NCs in the naming and semantic judgment tasks. These results provide evidence that CHI patients access semantic memory automatically at a normal rate. However, when the task is more demanding in terms of processing requests, then CHI patients' performance becomes defective.

Adult↗
PubMed1998

Retrograde memory deficits in severe closed-head injury patients.

A battery of tests evaluating different aspects of retrograde memory (autobiographical, public events, semantic knowledge) was administered to a group of 20 patients who had suffered from a severe closed-head injury (CHI) and who had recovered from the post-traumatic amnesia period and to a group of sex-, age- and education-matched normal controls. Results document a high prevalence of retrograde memory deficits among CHI individuals. The deficit involves both autobiographical and public events memories and extends to early acquired basic and cultural knowledge. The severity of the deficit does not vary according to some kind of temporal gradient or according to a presumed hierarchical or modality organization of the semantic system. However, in the domain of basic knowledge it more severely affects information pertaining to living than nonliving categories of objects. With the exception of a more severe deficit in retrieving autobiographical events occurred in the last year before trauma in a subgroup of patients with focal lesions restricted to the right hemisphere as compared to left lesioned patients, no clear relationship emerges between severity of the retrograde memory deficit and locus of focal cerebral lesions as demonstrated by neuroradiological exams.

Adolescent↗
PubMed1998

Analysis of the memory impairment in a post-encephalitic patient with focal retrograde amnesia.

This study aimed to characterize the qualitative pattern of focal retrograde memory impairment shown by a post-encephalitic patient (AV). AV's memory deficit encompassed autobiographical data, public events and famous people. In a public events questionnaire, she demonstrated a smooth negative temporal gradient with good recollection of events that occurred about 15 years before the disease but poor memory of more recent events. Her visual input lexicon was unimpaired, as demonstrated by normal lexicality judgment for words and normal familiarity judgment for proper names, but she was poor in familiarity judgment for famous faces (prosopagnosia) and in accessing the meaning of words or specific information about people. The cerebral MRI demonstrated widespread abnormal intensity areas encroaching upon the white matter of temporal, parietal and occipital lobes but sparing temporal poles and orbito-frontal cortex.

Adult↗
PubMed1998

Particle beam therapy (hadrontherapy): basis for interest and clinical experience.

The particle or hadron beams deployed in radiotherapy (protons, neutrons and helium, carbon, oxygen and neon ions) have physical and radiobiological characteristics which differ from those of conventional radiotherapy beams (photons) and which offer a number of theoretical advantages over conventional radiotherapy. After briefly describing the properties of hadron beams in comparison to photons, this review discusses the indications for hadrontherapy and analyses accumulated experience on the use of this modality to treat mainly neoplastic lesions, as published by the relatively few hadrontherapy centres operating around the world. The analysis indicates that for selected patients and tumours (particularly uveal melanomas and base of skull/spinal chordomas and chondrosarcomas), hadrontherapy produces greater disease-free survival. The advantages of hadrontherapy are most promisingly realised when used in conjunction with modern patient positioning, radiation delivery and focusing techniques (e.g. on-line imaging, three-dimensional conformal radiotherapy) developed to improve the efficacy of photon therapy. Although the construction and running costs of hadrontherapy units are considerably greater than those of conventional facilities, a comprehensive analysis that considers all the costs, particularly those resulting from the failure of less effective conventional radiotherapy, might indicate that hadrontherapy could be cost effective. In conclusion, the growing interest in this form of treatment seems to be fully justified by the results obtained to date, although more efficacy and dosing studies are required.

Central Nervous System Neoplasms↗
PubMed1998

Memory performances in young, elderly, and very old healthy individuals versus patients with Alzheimer's disease: evidence for discontinuity between normal and pathological aging.

In this study we compared memory performances of 29 probable patients with AD (17 mildly and 12 moderately demented) with those of 39 healthy young subjects, 36 elderly subjects (matched with the AD group for age and years of schooling), and 19 healthy very old subjects. In most of the memory tasks used in the present study, a progressive decline in performance was observed passing from the Young to the Elderly to the Very Old to the AD group. However, patients with AD were selectively impaired in the backward reproduction of verbal and spatial span sequences and in the semantic encoding of verbal material. These data are consistent with the hypothesis of not only quantitative but also a qualitative discontinuity between the process of normal aging and the dementia syndrome.

Adult↗
PubMed1997

Forgetting from long-term memory in severe closed-head injury patients: effect of retrieval conditions and semantic organization.

This study was aimed at investigating long-term forgetting in chronic survivors of severe closed-head injury (CHI). For this purpose, performance decay passing from a 30-sec- to a 60-min-delay test in four memory procedures (Free Recall of unrelated stimuli, Free Recall of related stimuli. Cued Recall and y/n Recognition) of 20 CHI and 20 normal controls was analyzed. Comparable 30-sec-delay performance in CHI and control patients were obtained by manipulating exposure times to study material during the learning phase. Results demonstrated accelerated forgetting in CHI patients in the Free Recall of the related list only. This finding was particularly evident in CHI patients suffering from a focal temporal lobe lesion. These data are discussed in light of retrieval and encoding deficits characterizing memory disorders in CHI patients.

Adolescent↗
PubMed1996

Recency effect in anterograde amnesia: evidence for distinct memory stores underlying enhanced retrieval of terminal items in immediate and delayed recall paradigms.

This study was devised to investigate immediate and delayed recency effects in anterograde amnesic patients. For this purpose, a word-list immediate recall paradigm and a modified version of the procedure devised by Baddeley and Hitch [Attention and Performance, Erlbaum, NJ, 1977] for eliciting the recency effect in delayed recall conditions was administered to a sample of amnesic patients and to a group of age-matched healthy subjects. Amnesics disclosed a fully normal recency effect in the immediate recall paradigm and a deficient recency effect in the delayed recall condition. These data, taken together with experimental evidence from a patient affected by a pure form of phonological short-term memory impairment [35], draw a double neuropsychological dissociation suggesting a differential origin for the two kinds of recency effects: a short-term memory output underlying enhanced recall of terminal items in immediate recall paradigms, and an ordinal retrieval strategy applied to long-term memory stored units at the root of the delayed recency effect.

Adult↗
PubMed1996

Perceptual and conceptual components in implicit and explicit stem completion.

This study was aimed at investigating functional and neuropsychological dissociations between repetition priming and explicit memory tasks. The explicit and implicit versions of the stem completion task were administered to a group of amnesics and a group of control subjects. In Experiment 1 both the explicit and implicit stem completions were significantly higher when the same presentation modality was used for studying and testing than when a change in modality from studying to testing occurred. Amnesics had normal implicit and deficient explicit completion performance. Experiment 2 revealed an advantage of the semantic over the phonological condition only in the explicit task and only in control subjects. Amnesic patients completed the same percentage of words as normal subjects in the phonological and semantic conditions of the implicit task and in the phonological condition of the explicit task but were deficient in intentionally completing semantically processed words. Possible interpretations of these results are discussed according to theoretical models that distinguish memory tasks along an explicit-implicit dichotomy (multiple memory system theory) or along a perceptual-conceptual dichotomy (transfer-appropriate procedures approach), and alternative theoretical positions are evaluated regarding repetition priming and memory deficits in amnesic patients.

Adult↗
PubMed1983

Preliminary observations on lung cancer therapy by interstitial irradiation with iodine 125.

Interstitial implantation of I125 by thoracotomy represents a further therapeutic procedure for lung cancer. Two cases recently treated by this procedure are reported. The first case concerns a right apical carcinoma of the lung where interstitial implantation of I125 seeds was carried out in the unresectable apical neoplastic residue, after superior lobectomy. The second case concerns a smaller tumor unresectable due to the severely impaired respiratory function. Main indications to the procedure are reported.

Aged↗
PubMedDate not supplied

Orbital pseudotumor: case report and literature review.

The term orbital pseudotumor refers to a broad category of non-specific idiopathic inflammations of the orbit. This disease, which may affect any orbital structure, is one of the commonest causes of exophtalmus, occurring with a similar incidence in both sexes. The diagnosis is based on a combination of clinical, radiological and histopathological findings, after careful exclusion of specific systemic and local diseases. Many classification systems have been proposed and a range of therapeutic modalities, including surgery, steroids, immunosuppressive agents, and radiation therapy, have been employed by various authors in heterogeneous series of patients. This slowly proliferating disease, which usually presents with a long clinical history and high variability in clinical manifestations and prognosis, is difficult to manage with any of the available therapeutic options. The difficulties and controversies regarding the diagnostic and therapeutic management of these patients are addressed in an updated review of the literature and exemplified in our case report.

Adult↗