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Biomedical subjects

C Carvajal

Publications and source records attributed to C Carvajal.

At least 19 recordsLinked to original sources
PubMed2006

Neuropeptide y: role in emotion and alcohol dependence.

Neuropeptide Y (NPY) is considered to be an important neuromodulator in the regulation of emotional behavior. For example, NPY is consistently involved in anxiety-related behaviors and there is increasing support for a role of this peptide in mood disorders such as depression. Furthermore, recent evidence suggests that NPY has a significant role in the neurobiological response to alcohol, including alcohol consumption, dependence, and withdrawal. In addition, NPY is beginning to emerge as an important modulator in the etiology of alcoholism that is independent from the addictive and reinforcing properties of the traditional system commonly associated with dopamine and instead, is strongly associated with innate emotionality. The recent developments elucidating the role of NPY in emotion and alcohol dependence are reviewed and the potential of the NPY system as a novel therapeutic strategy in the treatment of anxiety, depression and alcohol-related disorders is examined.

Alcohol-Induced Disorders, Nervous System↗
PubMed2002

Double dimer peptide constructs are immunogenic and protective against Plasmodium falciparum in the experimental Aotus monkey model.

Multiple antigen peptide constructs (MAPs) have been used to obtain defined multimeric peptide molecules useful in the development of possible synthetic malaria vaccines. In this context, a method was developed, named double dimer constructs (DDCs), involving the direct synthesis of a dimeric peptide with a C-terminal cysteine. A tetrameric molecule was then obtained by oxidation of sulfhydryl groups. Dimer synthesis was optimized using a Fmoc/tBu strategy, dimers were purified by HPLC, oxidized with DMSO and characterized by HPLC and MALDI-TOF-MS. The tetramers or DDCs obtained by this method were used as immunogens in the search for a possible malaria vaccine. It was found that they were immunogenic in the experimental Aotus monkey model, and were able to induce protective immunity when challenged experimentally with a highly infective Plasmodium falciparum malaria strain.

Amino Acid Sequence↗
PubMed2001

Synthesis, isolation and characterization of Plasmodium falciparum antigenic tetrabranched peptide dendrimers obtained by thiazolidine linkages.

Different chemical alternatives were evaluated for obtaining immunogenic polypeptidic macromolecules which could then be used as vaccines. These were based on the ligation reaction between an unprotected immunogenic peptide and an unprotected multifunctional core peptide; polyantigens, designated dendrimers because their form resembles that of dendritic cells, were thus obtained. The antigen-core ligation alternatives, studied by indirect synthesis, were the formation of oxime, hydrazone and thiazolidine linkages, making use of the reaction between a weak base (acting as nucleophile) and an alkyl aldehyde. The other alternative was the formation of a thioether linkage between a sulfydryl and an alkyl halide. Finally, a multiple antigen peptide (MAP) was synthesized by direct synthesis. All reactions were monitored by SEC-HPLC and SDS-PAGE. Dendrimer molecular mass obtained was confirmed by MS MALDI-TOF. Dendrimer purification was first carried out by concentrating crude reaction products with CP-5000 centricons and (using SEC-HPLC) pure tetramers were then obtained. A 20-residue 9376 immunogenic sequence, from Plasmodium falciparum apical merozoite antigen protein (AMA-1), was used to study the best alternative for chemical ligation. It was observed that thiazolidine formation proceeded with greater yield and in less time than the others. A tetramer has been simultaneously synthesized via thiazolidine with the SPf-66 antimalarial vaccine 45-residue monomer, proving the technique's versatility. The 9376 peptide disulfide bound polymer and SPf-66 (as well as their tetrameric thiazolidine dendrimers) were inoculated in rabbits to evaluate their antibody response. It was observed that titers for tetrameric thiazolidine dendrimers were not just greater but were also sustained over time. Western blot for pre-immune and immune sera showed that dendrimer sera recognized specific Plasmodium falciparum proteins as well as disulfide-bound polymers.

Aldehydes↗
PubMed2000

Clinical and cerebral blood flow changes in catatonic patients treated with ECT.

OBJECTIVE: To determine changes in clinical manifestations and cerebral blood flow (CBF) before and after administration of ECT to patients with catatonia due to schizophrenia or mood disorders. METHODS: A sample of nine patients who met DSM-IV criteria for catatonia was studied. Patients received between 5 and 15 sessions (thrice per week) of ECT. Severity of catatonia was measured with the Modified Rogers Scale (MRS). Changes in CBF were measured with a brain single positron emission computer tomography (SPECT) that was performed 1 week before the first ECT and 1 week after the last ECT. RESULTS: Catatonia was due to schizophrenia in five patients and mood disorders in four patients. There were no significant clinical and brain SPECT differences between these two groups before treatment. Pre- vs. post-ECT comparisons showed significant reduction of catatonic symptoms in both groups. However, patients with mood disorders needed less ECT sessions and showed greater clinical improvement. Brain SPECT showed significant increase in CBF in parietal, temporal, and occipital regions in patients with mood disorder and no significant changes in patients with schizophrenia. CONCLUSIONS: These results support the efficacy of ECT for treatment of catatonic patients, especially secondary to mood disorders, which seem to be correlated with improvements in CBF.

Adolescent↗
PubMed2000

Endothelial cell oxidative stress and signal transduction.

Endothelial dysfunction (ED) is an early event in atherosclerotic disease, preceding clinical manifestations and complications. Increased reactive oxygen species (ROS) have been implicated as important mechanisms that contribute to ED, and ROS's may function as intracellular messengers that modulate signaling pathways. Several intracellular signal events stimulated by ROS have been defined, including the identification of two members of the mitogen activated protein kinase family (ERK1/2 and big MAP kinase, BMK1), tyrosine kinases (Src and Syk) and different isoenzymes of PKC as redox-sensitive kinases. ROS regulation of signal transduction components include the modification in the activity of transcriptional factors such as NFkB and others that result in changes in gene expression and modifications in cellular responses. In order to understand the intracellular mechanisms induced by ROS in endothelial cells (EC), we are studying the response of human umbilical cord vein endothelial cells to increased ROS generation by different pro-atherogenic stimuli. Our results show that Homocysteine (Hcy) and oxidized LDL (oxLDL) enhance the activity and expression of oxidative stress markers, such as NFkB and heme oxygenase 1. These results suggest that these pro-atherogenic stimuli increase oxidative stress in EC, and thus explain the loss of endothelial function associated with the atherogenic process.

Arteriosclerosis↗
PubMed2000

[Improving the quality of clinical interview teaching: evaluation of an intervention with medical students].

BACKGROUND: Quality of clinical interview is a key issue both for patient satisfaction and for diagnostic efficiency. Its adequacy relates to better clinical diagnosis treatment plans and patient compliance. AIM: To measure the quality of interviews performed by medical students in three Chilean medical schools before receiving specific training on the subject and to compare the scores obtained after introductory courses on interview. MATERIAL AND METHODS: The interviews were videotaped and then evaluated using an objective scale, that measures 33 skills grouped in six areas: opening, problem exploration, non verbal facilitation, interpersonal patient reaction and closing. The students were assigned to an experimental group that received an interactive workshop with role-plays, vignettes and videotape feedback, and to a non intervention group that received the usual bedside training on medical interviews. RESULTS: Both groups shared the same skill level before the training, with better scores on nonverbal, patient reaction and problem exploration, and worse ones on closing and interpersonal skills. Comparing pre and post-test results, the overall score improved in the experimental group (from 33.2 to 38.3, p = 0.002) and worsened among non intervened students. There were statistically significant changes for opening (p < 0.002), problem exploration (p < 0.05), non verbal facilitation (p < 0.0001) and closing (p < 0.0001). CONCLUSIONS: It is important to train students not only in specific knowledge contents but in the process of interview. This training should encourage the development of empathy and closing skills.

Education, Medical, Undergraduate↗
PubMed2000

[BICAP tumor probe in the palliative treatment of malignant esophageal stenosis].

BACKGROUND: BICAP tumor probe is a device that consists in an energy source and olives that deliver bipolar electricity. It can be used for the fulguration of esophageal tumors after endoscopic dilatation. AIM: To report the experience in the treatment of malignant esophageal stenoses using the BICAP tumor probe. PATIENTS AND METHODS: Patients with advanced esophageal tumors in aphagia, that were not candidates for palliative surgery were included in this study. After endoscopic dilatation, the tumor was fulgurated with the BICAP tumor probe. RESULTS: Twenty one patients (nine male, aged 43 to 91 years old) were treated with the device. A mean of 1.3 sessions with BICAP were necessary to obtain tumor permeabilization, which was obtained in all patients. One patient died of pneumonia 15 days after the procedure. All other patients were ingesting liquid or semisolid diets after two months of follow up. Mean survival after the procedure was 3.8 months. CONCLUSIONS: Electrical fulguration of esophageal tumors is a valid therapeutic alternative in aphagic patients.

Adult↗
PubMed2000

[A new instrument for the evaluation of the medical profession. Use of the OSCE method].

BACKGROUND: Objective structured clinical examination has advantages over traditional oral examination of medical student. However, it is not routinely used in Chile. AIM: To describe the objective structured clinical examination system and report the results of its first use with Chilean medical students. MATERIAL AND METHODS: Thirteen interns ware evaluated at the end of their surgical rotation, using the objective structured clinical examination. Thirteen stations were structured for this examination: one for history taking, two for physical examination, four for problem solving and knowledge, one for radiological interpretation, one for instrumental recognition, one for skills and one for text comprehension. There were a total of 88 questions. RESULTS: All students exceeded 60% of requirements. Mean approval score was 73%. The higher score was 80% and the lower 61%. Ten students had a score over 70%. The method was well accepted by teachers and students. CONCLUSIONS: This first local experience with the objective structured clinical examination was successful.

Chile↗
PubMed1996

[Experience of a single center in liver transplantation in adults and children].

Orthotopic liver transplantation (THO) is the treatment of choice for a variety of liver diseases. The national experience before 1993 has been scarce. In November 1993 we started our experience in THO at Clínica Las Condes, as part of a multiorgan transplant program (liver, kidney, pancreas). Until January 1995 we have performed 14 THO in 13 recipients (one retransplantation), of which 5 were in pediatric cases. The recipients range of age fluctuated between 1 and 61 years. In two pediatric cases a liver allograft reduction was performed. Six recipients (46%) required treatment for acute cellular rejection. One recipient had an hepatic artery thrombosis and had to be retransplanted. There was no operative mortality up to 30 days in cases of primary liver transplants. The retransplanted adult recipient, and another pediatric recipient that died from a late recurrence of a hepatoblastoma, accounted for the mortality of this experience. After an average follow up of 10 months, the actual patient survival in 85%. Of the 11 surviving recipients, 9 are in excellent conditions with a very good quality of life. This experience shows that an active liver transplant program in our country can be successful in obtaining results comparable to those published by very experienced foreign transplant centers.

Adolescent↗
PubMed1995

[Hematological serological valves, and organ weight in adult Sprague-Dawley rats].

Sprague-Dawley rats are frequently used in experiments and their normal hematological, serologic and anatomical parameters are not easily available. The aim of this study was to measure these parameters in adult Sprague-Dawley rats. Twenty-four rats (12 males) whose weight ranged between 200 and 300 g, raised at the Instituto de Salud Pública in controlled environmental conditions and fed with pellets were studied. After a 24 h fast, animals were anesthetized with Droperidol and Ketamine, and after obtaining a cardiac blood sample, sacrificed by exsanguination. Most organs were withdrawn and weighed. Mean values for blood glucose, calcium, amylase, total proteins, cholesterol, AST, ALT, bilirubin, alkaline phosphatases, electrolytes and complete blood count were determined. Heart, lung, pancreas, kidney and testicle mean weight was also calculated. Male and female rats had significant differences in packed red cell volume, white blood cell count and hemoglobin.

Animals↗
PubMed1994

[Variations of the frequency of the diagnosis of depression in Chile].

Different publications have found an increase of depression diagnostic during last years. In this work chilean information available for the last decade in different hospitals (psychiatric, no psychiatric, public-private) is reviewed. Results confirm an increase of relative frequency of depressive disorders according to different classifications systems. Sex differences and possible explanations for this variation in diagnostic frequency are analyzed. Clinical practice would be the principal variable in this modifications.

Chile↗
PubMed1993

Dorsomedial thalamotomy as a treatment for terminal anorexia: a report of two cases.

Anorexia nervosa has been considered a compulsive obsessive disorder (OCDS). We present a case report of two patients, male and female, suffering from an extremely severe, chronic and refractory anorectic syndrome. Both patients underwent bilateral stereotactic thalamotomy with involvement of the lamella medialis. Follow-up was 4 year and 2 year, respectively. Both patients have regained weight and improved significantly in terms of their obsessive-compulsive symptoms and in their quality of life. The results suggest that anorexia nervosa may be considered in the OCDS.

Adolescent↗
PubMed1993

[Congenital hepatic fibrosis: an uncommon cause of portal hypertension].

Congenital hepatic fibrosis is an autosomic recessive disease, manifested in children or in young adults by hematemesis due to rupture of esophageal varices. Bacterial cholangitis may occur in some patients. Early diagnosis and treatment with portosystemic anastomosis and/or antibiotics may lead to a long survival with a good quality of life. Diagnosis requires histologic confirmation: normal hepatic lobules are surrounded by broad fibrous bands, and an increased number of bile ducts is usually seen in the portal tracts. Liver function remains well preserved. This report consists of 3 patients: a 17-year-old woman, a 10-year-old boy and a 24-year-old woman who developed severe upper GI bleeding due to ruptured esophageal varices. The first two patients were successfully operated on using the Sugiura technique for portal decompression. Their current survival after surgery is 3 and 9 years, respectively, with normal physical examination and liver function tests. The third patient died shortly after admission, due to the concurrence of a severe suppurative cholangitis.

Adolescent↗
PubMed1992

[Functional dysphonia: relation with personality and ICD-10 criteria].

The International Classification of Diseases, 10th. revision (ICD-10) in the category F45 defines the somatoform disorder as a mental disease characterized by the reiterative presentation of somatic symptoms in absence of an organic disease, or the somatic pathology being insufficient to explain the intensity of the symptoms as well as the discomfort and preoccupation of the patient. Fifteen female teachers with functional dysphonia were studied by means of a semistructured interview and psychometric evaluations. Considering dysphonia as the principal symptom, the most frequent diagnosis, in accordance with ICD-10 was "Other somatoform disorder" (F-45.8)(9/15). Five patients were diagnosed as motor dissociative disorder (F-44.4). All the patients had some abnormality of personality (5 with personality disorder and 10 with exacerbation of personality traits). The criteria of ICD-10 to classify the functional dysphonia as Somatoform disorder are discussed. It is suggested that certain personality traits are facilitators for somatization.

Adult↗
PubMed1992

[Assessment of knowledge of cardiopulmonary resuscitation].

The knowledge about standardized CPR of 41 physicians and 30 7th grade medical students was evaluated using a written multiple choice test. Results showed a severe lack of information about CPR in both groups; the test was approved by 39% of physicians and 10% of medical students. Among physicians, the lower achievements were obtained by traumatologists and the best by internists. The basic level of questions were approved by 63% of physicians and 43% of medical students. The principal deficiencies were on pharmacological management and CPR in trauma. It is concluded that education programs on CPR, similar to those given by the American Heart Association, are urgently needed among physicians and medical students.

Cardiopulmonary Resuscitation↗