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Biomedical subjects

P Alvarez

Publications and source records attributed to P Alvarez.

69 records · Page 4Linked to original sources
PubMedDate not supplied

Reaction time distributions across normal forgetting: searching for markers of memory consolidation.

Volunteers studied pictures of objects and were then tested for yes/no recognition at 10 min and 1 week after learning (experiment 1), or at 10 min and 4 months after learning (experiment 2). Because the gradual consolidation of long-term memory is thought to occur across this time scale (weeks and months), the reaction time distributions of successfully retrieved items were analyzed in an attempt to detect markers of consolidation. At each retention interval, reaction times for items retrieved successfully were well fit by a model that assumed a single underlying distribution. No evidence for a bimodal distribution of reaction times was observed. Furthermore, there was no evidence that some small subset of items was actually retrieved faster after a long retention interval than after a short interval. The results are consistent with the idea that consolidation works not to increase memory trace strength but to change the nature of memory storage. This process occurs during the course of normal forgetting and may not be observable in the behavior of normal memory.

Adult↗
PubMedDate not supplied

[Simultaneous micro-transplantation of fetal mesencephalic cells to the striate and substantia nigra pars reticulata in hemi-parkinsonian rats. A study of behavior].

INTRODUCTION: Microtransplantation of fetal dopaminergic cells has been used over the past ten years with good results in models of Parkinson's disease. OBJECTIVE: To evaluate the effect of microtransplantation of fetal dopaminergic cells 'seeded' in the substantia nigra pars reticulata (SNpr) and striate (St) simultaneously. MATERIAL AND METHODS: The animals received a transplant or microtransplant of cells into the St and SNpr ipsilateral to the lesion in the substantia nigra pars compacta or to both regions. Depending on the site and technique used the following experimental groups were considered: I. Macrotransplantation to the St (n = 20); II. Microtransplant to the St (n = 20); III. Microtransplant to St + SNpr (n = 20); IV. Microtransplant to St + SNpr (n = 20); V. Macrotransplantation to SNpr (n = 20); VI. Microtransplantation to SNpr (n = 20); and VII. Control (lesion only) (n = 20). The rotations induced by D-amphetamine (5 mg/kg i.p.) and by apomorphine were studied 1, 2, 3 and 6 months and 3 and 6 months respectively after transplantation. Three months after transplantation we studied the motor asymmetry shown by the animals by means of the ladder test. RESULTS: The rotations were reduced in the groups with intrastriate transplantation. Comparison between the surgical techniques showed nonsignificant differences between them. The ladder test showed significant differences in use of the limbs in all experimental groups. Use of the left limb was significantly reduced in all groups. CONCLUSIONS: Modification of the rotations seems more sensitive to the site of transplant than to the technique used. It seems that the skills studied using the ladder test are not altered by the microtransplant technique.

Animals↗
PubMedDate not supplied

[Changes in nerve growth factor levels related to age and neurotrophic treatment in non-human primate].

INTRODUCTION: To examine the amounts and role of growth factors in different tissues and corporal fluid, new sensitive techniques have to be developed. A major problem is that the normal concentration of trophic substances, such as nerve growth factor (NGF), in central and peripheral nervous system and in fluids is very low (ng pg/ml). A valuable method of research is the sensitive two site enzyme immunoassay using the monoclonal antibody 27/21 to mouse NGF. Materials and methods. The present work applied this enzyme immunoassay to examine the NGF levels in normal non human primate sera (n= 94) and applied this assay to study of NGF levels in two non human primate receiving NGF infusion: one young and one aged. Two groups of non human primate sera were studied one young adult (n= 69) and one aged (n= 25). The serum samples NGF treated non human primate were taken before the infusion and at the 1st week and 1st, 3rd, 6th and 12th month after infusion. RESULTS: To further test the specificity of conjugate binding, dilutions of the non human primate sera were preincubated with an excess of monoclonal NGF antibody 27/21 in solution. With this strategy it was possible to completely block the signal obtained using the enzyme immunoassay. We found very low levels of NGF in aged monkeys (0.054 ng/ml) when compared with young adult group (0.152 ng/ml) (p> 0.01). The NGF levels in aged non human primate treatment with NGF was very low before (0.50 ng/ml) and during NGF treatment evolution time, whereas at the the 12th month showed an increase in NGF levels (0.180 ng/ml). We found normal values of NGF in the young monkey before and during the first year after NGF infusion. CONCLUSIONS: Using the enzyme immunoassay described it is possible to know the serum concentration of NGF immunoreactive in non human primate and this assay is able to detect peripheral changes in NGF levels after intracerebral infusion of NGF.

Age Factors↗
PubMedDate not supplied

[Adoerse effects by the administration of salicylates].

Two cases that illustrate one of the side-effects of salicylates are presented. Both cases manifested as non thrombocytopenic purpura. Indications and contraindications for the use of salicylates are described. Emphasis is made not to use them as analgesics or antipyretics in cases with congential or acquired defects in the coagulation mechanism. Other side-effects of salicylates are described.

Blood Coagulation Disorders↗
PubMedDate not supplied

[Neuroendocrine disturbances in obesity].

Obesity is associated with different disturbances in endocrine function. Both spontaneous growth hormone (GH) secretion and its response to several stimuli have shown to be reduced in obese patients. The GH responses to GH-releasing hormone and other challenges by pyridostigmine suggest that the reduction in GH secretion is related to an increased somatostatinergic tone. Other experiments point to a down-regulation of somatostatin receptors in the somatotroph cell. Ghrelin administration is followed by a massive GH release, but the possibility that ghrelin or GHRH deficiency are the cause of GH deficiency in obesity is unlikely. The increase in free fatty acids in obesity might be related to GH reduction, since acipimox administration is able to reverse GH secretion. In women, abdominal obesity is associated with hyperandrogenism and low sex hormone-binding globulin levels. Obese men have low testosterone and gonadotrophin concentrations, specially in cases of morbid obesity. An increase in hypothalamic-pituitary-adrenal axis activity and some resistance to dexamethasone suppression have been described in abdominal obesity. This effect may be due to neuroendocrine alterations related to a genetic origin. Adrenal hyperfunction may favour cardiovascular and metabolic complications. There are no disturbances in thyroid function. Sometimes a reduction in prolactin response to several stimuli has been reported. This effect may be due to hyperinsulinaemia or to disturbances in the dopaminergic tone.

Animals↗
PubMedDate not supplied

[Chinese Polarity Inventory: its adaptation to our setting].

INTRODUCTION: The Chinese Polarity Inventory (CPI) is a self-report scale for bipolar disorder assessment, composed of two scales (mania and depression), with 20 items for each one. OBJECTIVES: Translate, adapt and validate the CPI to our context. MATERIAL AND METHODS: The questionnaire was applied to 123 patients: bipolar disorder in the manic phase (32), depressed (17), remission (30) and mixed state (3). We also established a control group with 30 patients without affective disorder. Internal consistency was assessed using Cronbach's alpha. On the other hand, validity was established using the Clinician Administered Rating Scale for Mania (CARS-M) in manic patients and the Hamilton scale in the depressed ones as a gold standard. RESULTS: This scale has good psychometrics qualities. Internal consistence index (Cronbach's alpha) for the manic scale was 0.90 and for depression scale was 0.92. The correlation coefficient between the manic scale and the CARS-M was 0.82 and between the depression scale and the Hamilton scale was 0.67. CONCLUSIONS: The CPI is an instrument of rapid and easy application that permits self-report of bipolar disorders. The best benefit for this scale is the possibility of application in the entire course of illness, for clinical and investigation activities and assessment of the treatment response.

Adolescent↗
PubMedDate not supplied

[Manifestations of paralytic ileus in infants hospitalized for acute diarrheal syndrome].

In order to assess and characterize adynamic ileus (AI) complicating acute diarrhoea (AD) in infants, 802 consecutive admissions were studied. Diagnosis was suspected in 23 patients with abdominal distension and confirmed by radiological study in 16 whose age range was 14 ds to 6 mo. Of these late patients, 9/16 were malnourished. Age was less than, but nutritional status similar to that of all patients admitted with ADD. Vomiting (14/16), silent or almost silent abdomen (10/16), protracted course of diarrhoea (9/16) and increased gastric content (6/16) were the most common clinical findings in addition to abdominal distension and X Ray films suggestive of AI (inclusion criteria). Lack of constipation was a relevant finding. Treatment included temporal discontinuance of oral feedings, intravenous fluids administration, nasogastric and rectal tube and antibiotics. Lethality rate was 4/16. Duration of AI was an average of 2 days in survivors and 4 days in the remainder infants. It is concluded that AI is an infrequent complication of AD (0.19% of cases), which should be suspected in infants less that 6 mo old with diarrhoea and abdominal distension.

Acute Disease↗
PubMedDate not supplied

[Appetite and nutrition].

Physiological, pathological and therapeutic aspect of appetite are reviewed. The importance of developmental alterations originated at early infancy and lack of appropriate interactions between mother and infant in abnormalities of appetite are emphasized. The role of vitamins, minerals and appetite stimulating drugs is analyzed and major disturbances of appetite and feeding conducts are described together with some therapeutic considerations on anorexia nervosa, bulimia, pica and rumination.

Anorexia Nervosa↗