Biomedical subjects

L Alvarez-González

Publications and source records attributed to L Alvarez-González.

8 recordsLinked to original sources

PubMed1998

[Factors that lead to death of neurons in neurodegenerative diseases].

OBJECTIVE: The objective of this paper was to review information related to the various factors which may trigger the mechanisms of cell death, induced or programmed, which take place in the nervous system and their relationship with the aetiopathogenesis of the neurodegenerative diseases. DEVELOPMENT: In recent years it has been recognized that cell death may be not only the consequence of accidental damage but also a sign of a suicide programme. This form of death is currently known as apoptosis. It is a process which is morphologically distinct from accidental cell death or necrosis. It does not cause an inflammatory response. This type of death is not only involved in the development and haemostasis of tissues, but also in setting off neuronal degeneration in experimental models of Parkinson's disease, Huntington's chorea, etc. CONCLUSIONS: In the cell death occurring in neurodegenerative diseases there is more than one induction mechanisms. Understanding the factors which trigger cell death, and the chain of events leading to this, gives grounds for the design of new pharmacological strategies for the treatment of these diseases.

Calcium↗

PubMedDate not supplied

[Effects of simultaneous transplant of foetal mesencephalic cells in the striatum and the subthalamic nucleus of hemiparkinsonian rats].

INTRODUCTION: The main strategy followed in neural transplants as a method of treatment for Parkinson s disease, both experimental and clinical, has been to introduce foetal mesencephalic cells into the target area: the striatum. However, when the dopaminergic cells in the substantia nigra degenerate, not only is the dopaminergic innervation of the striatum affected but also other nuclei: globus pallidus, substantia nigra, substantia nigra pars reticulata and subthalamic nucleus. A series of data from pharmacological and physiological studies offer strong evidence that the dopamine released in these nuclei may play an important role in regulating the output nuclei of the basal ganglia. AIM: To evaluate the effect of transplanting foetal mesencephalic cells on the behaviour of 6 OH DA rats when introduced into the striatum and the subthalamic nucleus. MATERIALS AND METHODS: 6 OH DA was used to induce lesions in the substantia nigra of rats, which were divided into several experimental groups. The rotating activity induced by D amphetamine (5 mg/kg, intraperitoneally) and apomorphine (0.05 mg/kg, subcutaneously) was evaluated before and three months after the transplant in all the experimental groups, except in the control group of healthy rats. The hemiparkinsonian rats received a total of 350,000 foetal ventral mesencephalic cells, which were implanted within small deposits in the striatum (8) and in the subthalamic nucleus (4). RESULTS AND CONCLUSIONS: Rotation induced by both drugs was significantly lower (p= 0.05) in animals that had had dopaminergic cells transplanted into the striatum body. No significant improvement in this behaviour was to be found when transplants were limited to just the subthalamus or, simultaneously, also to the striatum. A significant increase in rotating behaviour induced by apomorphine was observed in the group which received a transplant in just the subthalamus.

Adrenergic Agents↗

PubMedDate not supplied

[Database application for information on post-surgical evolution after functional neurosurgery].

INTRODUCTION: A series of quantitative scales have been established internationally to evaluate the functional state of patients affected by movement disorders, such as Parkinson s disease. The values of these parameters offered by each patient, measured at different moments during his or her illness, allow us to conduct studies into their evolution as well as perform statistical studies about the casuistics. AIM. To provide a tool that enables us to study this vast amount of material in an efficient, sure and, above all, automated manner. Materials and methods. We selected the most interesting variables from the international protocols. We also designed and developed a database application for use under the Windows environment using Delphi 3.0 language and compiler and Structured Query Language. RESULTS: We designed, developed and validated a database system so as to be able to handle automatically the information on the clinical evolution of patients who had undergone functional neurosurgery. This system not only enables us to collect all relevant pre and post surgical information but also allows fast searches and selection, data processing using descriptive statistical techniques and the exportation of the data in a standard format. The system, which also allows final double blind clinical evaluation of each patient to be performed, has been used successfully in the Movement Disorders Clinic at the CIREN for over three years. CONCLUSIONS: This system allows for a considerable saving in the amount of time and effort needed for the post surgical evolution of patients, while also increasing the reliability of the results obtained.

Databases, Factual↗

PubMedDate not supplied

[Subthalamic nucleus targeting and spatial variability].

AIM: The effectiveness of anatomic localization of the subthalamic nucleus (EAL) was assessed and the mapping method is described here. The symmetry of contralateral nuclei (SCN) was analyzed on 11 parkinsonian patients submitted to bilateral subthalamotomy with ablative lesioning. PATIENTS AND METHODS: To assess EAL the percentage so much of first trajectory (p1) as the total of trajectories (pt) that hit the target and the rest of subthalamic nucleus average distance (d) was calculated. The anatomic localization error (epsilon) is determined as a difference between first trajectory coordinates with those of medial determined nucleus point, through electrophysiological data as to the statistical significance of this error. SCN is analyzed by contrasting equality hypothesis at the nucleus maximum height alongside a trajectory, average electrophysiological position center and spatial distribution of all intranuclear recordings found in each hemisphere in all patients. RESULTS: The pi, pt and d obtained values were 86.36%, 86.13% and 1.41 +/- 1.01 mm respectively. The epsilon value was greater in anteroposterior direction of 1.11 +/- 0.83 mm without statistical significance. The average number of recorded trajectories for the first procedure was 6.45 and 6 for the second. The asymmetry of contralateral nucleus was not significant. CONCLUSIONS: An indirect method with CT brain images and a new electrophysiological mapping method with a multiunitary recording for first and second nucleus is safe enough and it yields a high effectiveness in anatomofunctional nucleus localization. The nucleus of a same patient are symmetrical. There is little space variability among patient non related to the differences in the intercommissural distance.

Aged↗

PubMedDate not supplied

[Lesions in the pars compacta substantiae nigra and the subthalamic nucleus modify the density of muscarinic receptors in different nuclei of the basal ganglia].

INTRODUCTION: Several studies that has focused to the dopaminergic transmission in the basal ganglia in parkinsonian condition, but only a few article has taking into account the imbalance between dopaminergic and cholinergic transmission. OBJECTIVE: To evaluate the muscarinic cholinergic receptors density in SNc and PPN in the 6-OHDA model. MATERIALS AND METHODS: Were organized five experimental groups in correspondence to the place of the lesion: I. Non treated rats, II. 6-OHDA lesion in SNc, III. 6-OHDA lesion in SNc + quinolinic acid lesion in NST, IV. Sham operated rats, V. Quinolinic acid in STN. Were obtained coronal sections of 20 microm thickness of SNc and PPN from rats and in these sections was evaluated the muscarinic receptors density through autoradiographic technique with [3H]quinuclidinylbenzilate (QNB) (1.23 nM). The muscarinic antagonist atropine (1 microM) was utilized as non-specific union. The density was evaluated in both hemispheres and the density optical was converted in fentomolas/mg of tissue with base to values obtained from tritium standards. RESULTS: Significant diminution of the muscarinic receptors density was found in the SNc ipsilateral to the 6-OHDA lesion from experimental groups II (t=2.76; p<0.05) and III (t=4.06; p<0.05). In the group V, was seen a significant increase of muscarinic receptor density in the SNc ipsilateral to the 6-OHDA lesion. The comparison between experimental groups evidenced significant differences among them (F=13.13; p<0.001) with a significant decrease in the density from SNc of groups II and III and significant increase in the density from SNc of group V in comparison of the others groups. In relation to PPN, muscarinic receptors density from right PPN ipsilateral to the 6-OHDA lesion, shown significant differences (F=3.93; p<0.01) between the experimental groups with a significant increase of this variable in the group II. CONCLUSIONS: These results signal a modification of cholinergic activity after 6-OHDA lesion. The changes in the muscarinic receptors populations located in SNc and PPN could be part of different compensatory mechanisms to attempt ameliorate the imbalance between dopaminergic and cholinergic transmission that it was installed after denervation of nigrostriatal forebrain bundle. The excitotoxic lesion of STN impose a new adjust mechanism for cell from PPN, which could be expressed in the changes of muscarinic cholinergic receptors population at the level of SNc.

Animals↗

PubMedDate not supplied

[A clinical and epidemiological description of a series of patients diagnosed as suffering from progressive supranuclear palsy].

INTRODUCTION: Progressive supranuclear palsy is a disease that normally presents only sporadically in adults and courses in a progressive, chronic manner. It is characterised by the presence of supranuclear ophthalmoplegia, postural instability, a Parkinsonian syndrome, pseudobulbar affect, cervical dystonia and cognitive impairment. PATIENTS AND METHODS: We conducted a descriptive study of clinical and epidemiological features in a series of 18 patients who satisfied the mandatory NINDS-SPSP clinical eligibility criteria for the likely diagnosis of progressive supranuclear palsy, using the scale developed by Golbe et al. RESULTS AND CONCLUSIONS: The mean age of onset of the disease was 58.6 +/- 8.2 years, 55.5% of the patients were males, the average history of the disease at the time of diagnosis was 4.39 +/- 2.3 years, and there was a diagnostic subregister in the first 4 years of the disease. Gait disorders, falls and slowness were the most frequently observed presenting forms of the disease. During their first four years with the disease, 75% of the patients were totally independent when it came to carrying out activities of daily living, whereas after the fourth year there was a predominance of the need for aid and absolute dependence. Dysphagia was more frequent in the later stages of the disease. Ocular motility disorders and impaired cognitive functioning were obvious in the initial stages of the disease, and there was a strong correlation between the length of time the disease had been coursing and the severity of the ocular and cognitive disorders.

Cognition Disorders↗

PubMedDate not supplied

[The effects of lesions in the compact part of the substantia nigra on glutamate and GABA release in the pedunculopontine nucleus].

INTRODUCTION: The pedunculopontine nucleus (PPN), co-localized with the mesencephalic locomotor region, has been proposed as a key structure in the physiopathology of Parkinson's disease. OBJECTIVES: The goal of the present study was to assess if the aminoacid neurotransmitter release in the PPN is modified by the degeneration of dopaminergic cells, from substantia nigra pars compacta in 6-hydroxidopamine (6-OHDA)-lesioned rats. In addition, it was studied the aminoacid neurotransmitter release in the PPN of rats with lesion of the subthalamic nucleus by quinolinic acid (QUIN) (100 nmol) intracerebral injection. MATERIALS AND METHODS: Rats were assigned to five groups: untreated rats (I) (n = 13), 6-OHDA lesion (II) (n = 11), 6-OHDA + QUIN lesion (III) (n = 9), sham-operated (IV) (n = 10), QUIN, STN (V) lesioned (n = 9). The extracellular concentrations of glutamic acid (GLU) and gamma-aminobutyric acid (GABA) were determined by brain microdialysis and high performance liquid chromatography (HPLC). RESULTS. GLU released in PPN from 6-OHDA lesioned rats (group II), was significantly increased in comparison with the others groups (F(4, 47) = 18.21, p < 0.001). GABA released shows significant differences between experimental groups (F(4, 45) = 12.75, p < 0.001). It was detected a higher valour (p < 0.05) in-group II. The groups III and IV exhibited intermeddle valour (p < 0.001) and groups I and IV (p < 0.001) showed the lower GABA extracellular concentrations. The infusion of artificial cerebrospinal fluid with higher potassium (100 mmol) induced an increase in the GLU and GABA released in all groups, which confirm the neuronal origin of the extracellular content. CONCLUSION: These results are in agreement with the current model of basal ganglia functioning and suggest the role of STN-PPN projection in the physiopathology of Parkinson's disease.

Adrenergic Agents↗

PubMedDate not supplied

[Frontal dysfunction in idiopathic Parkinson's disease].

INTRODUCTION: In his description of the disease in his original work, James Parkinson claimed that the 'senses remained intact', but later reports began to identify cognitive impairment that ranged from dementia to barely identifiable subclinical deteriorations. Research carried out in recent decades has revealed that cognitive disorders form part of the clinical symptoms of Parkinson's disease (PD) and point to the frontal lobes as being the most affected areas; a great deal of controversy, however, still surrounds their definition, epidemiology and pathology. AIM: To determine and classify the frontal deficits associated to this disease and to relate this cognitive performance with certain characteristics of the disease. SUBJECTS AND METHODS: The sample utilised in the study was made up of 222 subjects divided into two groups according to their diagnosis: 111 subjects with idiopathic PD and 111 control subjects. The neuropsychological examination was performed using the Frontal Assessment Battery, the copy of the Rey-Osterrieth complex figure and the digit test for determining frontal functioning. RESULTS AND CONCLUSIONS: We prove the existence of a frontal dysfunction that is characterised by impaired working memory, with visuospatial and executive dysfunction, which suggests greater involvement of the dorsolateral prefrontal cortex and cingulate. According to our findings, because working memory and visuospatial functioning are correlated to the motor status and the time elapsed since the onset of the disease, they could share the same underlying neuroanatomical foundations--the nigrostriatal denervation. This is not the case of executive function, which was not found to be related to the characteristics of the disease under study.

Cognition Disorders↗