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Biomedical subjects

A Donoso

Publications and source records attributed to A Donoso.

At least 19 recordsLinked to original sources
PubMed2001

Quantum tunneling using entangled classical trajectories.

In this Letter, we present a new method for simulating quantum processes in the context of classical molecular dynamics simulations. The approach is based on solving numerically the quantum Liouville equation in the Wigner representation using ensembles of classical trajectories. Quantum effects arise in this formulation as a breakdown of the statistical independence of the ensemble. New interaction forces between ensemble members are derived, which require the trajectory ensemble representing the state to evolve as an entangled, unified whole. The method is applied to the simulation of quantum tunneling in a one-dimensional model system, yielding excellent agreement with exact quantum calculations.

Journal Article↗
PubMed1999

[Cognitive stimulation workshops in old age: preliminary experience].

OBJECTIVE: To test the utility of cognitive stimulation in a group of healthy older people. DESIGN: A pilot study in 11 healthy women from Conchali council. All of them were evaluated before and after stimulation using Minimental State Examination of Folstein (MM), Memory Wechsler Scale (MW) and Geriatric Depression Scale (GDS). PARTICIPANTS: Were selected from a group of regularly participants in center for seniors, aged 60 years or more (mean 66.6 years old), able to read and write (mean scholarship 5.3 years). INTERVENTION: 16 workshop of 90 minutes, twice a week during 2 months. They had motivation pantomime plays, memory activities and so on. RESULTS: Wilcoxon signed rank pre and post workshop for MM was -2.633 (p = 0.008), for MW was -2.938 (p = 0.003) and for GDS was -2.943 (p = 0.03). CONCLUSIONS: Cognitive stimulation could be useful in older people. It is necessary to increase the sample.

Aged↗
PubMed1999

[Retraction of lower limbs in a female with hyperthyroidism].

We report a 47 years old woman with hyperthyroidism that had a severe tendinous retraction of hips and knees that subsided with propylthiouracil treatment. Electrodiagnosis showed myopathic alterations and muscle strength was moderately reduced. The authors did not find references of a similar condition in patients with hyperthyroidism.

Endocrine System Diseases↗
PubMed1995

[Melkersson-Rosenthal syndrome: report of 3 cases].

Melkersson-Rosenthal syndrome is characterized by facial or lip edema, peripheral facial palsy and scrotal tongue. We report three patients with the syndrome. A 17 years old male had malar and superior lip enlargement that coincided with a peripheral facial palsy. A 40 years old male with recurrent facial palsy presented with episodes of contralateral facial enlargement. A 32 years old female consulted for a hypertrophy of labia minora and majora and facial infiltration. Biopsies showed a granulomatous cheilitis in all cases. Two patients were treated with clofazimine with partial results. The female patient did not accept plastic surgery.

Adolescent↗
PubMed1994

Blood markers in Alzheimer disease: subnormal acetylcholinesterase and butyrylcholinesterase in lymphocytes and erythrocytes.

In patients with the clinical diagnosis of Alzheimer disease (AD), we searched for systemic changes in components of the blood as a diagnostic tool. The acetylcholine-related enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were measured in plasma, erythrocytes, platelets and lymphocytes. Results did not show a general effect; notwithstanding, specific cell types presented alterations either in AChE or BuChE but not in both enzymatic activities. In AD patients, AChE of lymphocytes was reduced by 60% compared with the age-matched controls. However, when patients were divided, the sporadic but not the familial subgroup exhibited a significant reduction. In erythrocytes the BuChE activity was reduced by 45% in sporadic AD. The molecular forms of the lymphocyte AChE were characterized by velocity sedimentation. Both globular forms were subnormal, more so the tetrameric G4 AChE form than the G2 form.

Acetylcholinesterase↗
PubMed1994

[Prefrontal dementias: clinical features and SPECT in 6 cases].

Six patients with primary degenerative dementias and frontal or frontotemporal hypoperfusion are reported. Five were diagnosed as Frontal Progressive Dementia (FPD), characterized by striking changes in personality and social behavior. The last patient had a progressive aphasia and a moderate cognitive impairment. We discuss the heterogeneity of FPD that includes Pick's disease, frontal lobe type dementia (Neary) and progressive subcortical gliosis. The usefulness of SPECT and the need of a brain bank are remarked.

Aged↗
PubMed1993

Platelet of Alzheimer patients: increased counts and subnormal uptake and accumulation of [14C]5-hydroxytryptamine.

Platelets are the main source of 5-hydroxytryptamine (5-HT) and amyloid precursor protein (APP) found in plasma. We studied a possible correlation between platelet markers and the clinical diagnosis of Alzheimer disease (AD). Our results indicate that in AD patients: (a) platelets are elevated, (b) their ability to accumulate 5-HT decreases and, (c) the kinetic parameters of 5-HT uptake are altered (decreased Km and Vmax), compared to non-demented healthy individuals. An aged Down syndrome patient presents even more deviant alterations. Our findings supports the idea that platelets may provide a systemic marker of AD, and eventually be useful for the clinical diagnosis of the disease.

Aged↗
PubMed1991

[Pharmacological treatment of Alzheimer's disease].

Management of Alzheimer disease includes sedatives, neuroleptic and hypnotic agents for behavior disorders family-directed therapy; activities to maintain functional abilities; care of overall health status and disease specific therapies. The therapeutic attempts specifically based on known or postulated neurophysiological abnormalities are the neurotransmitter replacement therapies (cholinergic enhancement strategies and others); the treatment or prevention of cytoscheletical abnormalities and the neuronal metabolic enhancement with nootropics. There is no definitely useful specific therapy for Alzheimer disease at present. However, increasing research on cholinergic mechanisms, galaninergic interneurons, nerve growth factor and neural grafts, metabolism of amyloid an others, will hopefully lead to useful therapies in the near future.

Alzheimer Disease↗
PubMed1990

[Alzheimer-type dementia: clinical experience in 71 cases].

The clinical criteria used for making the diagnosis of dementia of the Alzheimer type are featured, presenting the experience with 71 patients who fulfilled those prerequisites. The manifestations began generally over the age of 60, predominantly in females, and frequently there was a history of affection in other family members. The symptoms most frequently found were memory defects, lack of abstraction and anosognosia. The diagnosis depended most often on the clinical findings rather than the laboratory studies, which could be normal. It is worth noting the variable clinical courses found indicating that we are dealing with a heterogeneous population. It is suggested that dementia of the Alzheimer type and normal senility are not contrasting conditions but rather a continuum of the same process.

Age Factors↗
PubMed1989

[Difficulties in the diagnosis of dementia].

We evaluated 125 ambulatory patients with a clinical syndrome of dementia. About half of them met criteria for diagnosis of Alzheimer's disease; vascular disorders and other etiologies were less prevalent. Among 176 patients with initially suspected Alzheimer's disease, this diagnosis was confirmed by clinical findings and follow up in 70%. Psychiatric disorders were responsible for the syndrome in 20%, other etiologies were less frequent. In the absence of specific markers for Alzheimer's disease this diagnosis should be established only after careful clinical studies and follow up. No clear limits between Alzheimer's disease and functional cerebral loss from aging can be defined at this time.

Aged↗