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C Salas

Publications and source records attributed to C Salas.

At least 19 recordsLinked to original sources
PubMed2003

Spatial and non-spatial learning in turtles: the role of medial cortex.

In mammals and birds, hippocampal processing is crucial for allocentric spatial learning. In these vertebrate groups, lesions to the hippocampal formation produce selective impairments in spatial tasks that require the encoding of relationships among environmental features, but not in tasks that require the approach to a single cue or simple non-spatial discriminations. In reptiles, a great deal of anatomical evidence indicates that the medial cortex (MC) could be homologous to the hippocampus of mammals and birds; however, few studies have examined the functional role of this structure in relation to learning and memory processes. The aim of this work was to study how the MC lesions affect spatial strategies. Results of Experiment 1 showed that the MC lesion impaired the performance in animals pre-operatively trained in a place task, and although these animals were able to learn the same task after surgery, probe test revealed that learning strategies used by MC lesioned turtles were different to that observed in sham animals. Experiment 2 showed that the MC lesion did not impair the retention of the pre-operatively learned task when a single intramaze visual cue identified the goal. These results suggest that the reptilian MC and hippocampus of mammals and birds function in quite similar ways, not only in relation to those spatial functions that are impaired, but also in relation to those learning processes that are not affected.

Animals↗
PubMed2003

Spatial reversal learning deficit after medial cortex lesion in turtles.

Many comparative pieces of research support the hypothesis that the medial cortex region of the reptilian forebrain could be homologous to hippocampal formation. Besides, there is some evidence involving this structure in complex spatial learning in a similar manner to hippocampus of mammals and birds. In this experiment we examined effects of medial cortex lesion in reversal learning. Turtles were trained in a spatial and a non-spatial maze procedure and the reversal of these tasks. Data revealed that sham and medial cortex lesioned turtles of both procedures performed well on the initial learning (acquisition). However, during the reversal phase, only the turtles with medial cortex lesion showed impaired performance in the spatial procedure. These results suggest that turtles possess different spatial learning and memory systems in close parallel to those described in other vertebrates, and that medial cortex plays a crucial role in complex place learning.

Animals↗
PubMed2003

Current induction immunosuppression and post-heart transplant lymphoproliferative disorders.

BACKGROUND: The use of high-dose OKT3 has been reported to be associated with a high incidence of posttransplant lymphoproliferative disorders (PTLD) in heart transplantation (HTx) recipients. The incidence and characteristics of PTLD with current induction protocols remain largely unknown. The aim of our study was to analyze the incidence and characteristics of PTLD in a large series of HTx recipients treated with low-dose OKT3 induction. METHODS: From 1984 to 2002, a retrospective review of diagnosis, treatment, and evolution of PTLD cases was performed on the 560 patients who underwent HTx in our center. RESULTS: The incidence of PTLD was 1% (6/560). The disease occurred early after HTx in two cases and between 13 and 121 months in the other four. Molecular studies showed evidence of Epstein-Barr virus (EBV) infection in four patients. B-cell proliferation was observed in five cases, and T-cell proliferation in the other one. Various therapies were employed for each patient. Ganciclovir and reduction in immunosuppression were the most common measures. Interestingly, OKT3 was used as a specific anti-T-cell proliferation agent with some success in the one case of T-cell PTLD. Complete remission was achieved in just two patients, whereas the other four (67%) died, mostly due to other conditions. CONCLUSIONS: The use of low-dose OKT3 as induction therapy did not increase the incidence of PTLD in our series. Late appearance of disease prevailed among our patients. Despite a multidisciplinary approach to therapy, including the use of OKT3 against T-cell proliferation, the mortality rate was high (67%).

Adult↗
PubMed2003

Development of interface in hydroxyapatite implanted in the middle ear of the rat: a light and scanning microscopy study.

OBJECTIVE: The aim of this work is to study the chronology in the biological covering of the hydroxyapatite bioprostheses in the healthy middle ear of the rat. STUDY DESIGN AND SETTING: Dense hydroxyapatite is implanted into the middle ear of 45 Long-Evans rats, between stapes and tympanic membrane. The sample was divided into 3 groups for morphologic, functional, and chemical studies at 15 days, 3 months, and 6 months after surgery, respectively. RESULTS: The short-term studies reveal that the prostheses is surrounded by a fibrous epithelial tissue referred as the interface; it presents a marked inflammatory reaction that decreases gradually in the medium-term and long-term studies; in this way, we observe a progressive adhesion between implant and the contact tissues. CONCLUSIONS AND SIGNIFICANCE: This model has enabled us to study the cell reaction produced by the contact of the prostheses with bone and soft tissue and their impact on the functional qualities of the prostheses.

Animals↗
PubMed2002

[Study of pulmonary lesions with (99m)Tc-Tetrafosmin and chest spect. Determination of uptake related factors, diagnostic value and prognosis].

One hundred fifteen patients with 119 pulmonary lesions in which malignancy was suspected underwent a SPECT study with 99mTc-Tetrofosmin (TTF) to assess the possible factors involved in the uptake of the radiopharmaceutical. The TTF uptake rate in the lung tumor with respect to that of healthy tissue (TTF index) was evaluated in terms of: benignity and malignancy, histological type, stage, cell differentiation, size, necrosis, survival and the influence of P-glycoprotein (Pgp), detected by immunohistochemistry, on the TTF uptake. The mean TTF index in the 18 benign lesions studied was 1.01 0.05, while that of the 101 malignant lesions was 1.59 0.45 (p < 0.001), with a positive predictive value of 97.7% and a negative predictive value of 50%. The comparison of the histological types, degree of cell differentiation, necrosis and stage revealed no statistically significant differences. With respect to size, those tumors measuring > 3 cm showed greater uptake than smaller lesions. In patients with non-small cell lung cancer, a positive relationship was observed between the TTF index and survival, a circumstance that did not occur in patients with small cell lung cancer. In the cases in which the presence of Pgp was assessed, there was an inverse relationship between the TTF ratio and Pgp expression. In conclusion, thoracic SPECT with 99mTc-TTF has a high positive predictive value for the presence of lung cancer, although a negative study does not rule out the existence of the disease. The reason for this is the inverse relationship between 99mTc-TTF uptake and the density of Pgp expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Econometric issues in testing the age neutrality of health care expenditure.

A recent study by Zweifel et al. (Zweifel P, Felder S, Meiers M. Ageing of the population and health care expenditure: a red herring? Health Economics 1999; 8: 485-496) suggests that age is not related to health care expenditure among the elderly once 'closeness to death' is controlled for. If correct, this finding has major policy implications, but flaws in the econometric analysis undermine its credibility. We highlight two in particular, and propose methods to deal with them.

Age Factors↗
PubMed2001

Eye-movement recording in freely moving animals.

A new method is described for precise recording of eye movements in freely moving animals using Hall-effect devices. This inexpensive system, of small size and low weight, allows the analysis of horizontal and vertical components of saccadic eye movements, optokinetic nystagmus, slow tracking movements, eye vergence, etc., in unrestrained animals. A set of Hall-effect devices mounted in the skull is used to sense variations in the position of high-power miniature magnets fixed to the eye sclera. The output of the Hall-effect devices is amplified by operational amplifiers and collected through an analog-to-digital converter to be displayed on-line in a personal computer and stored for later analysis by specific software. Some examples of simultaneous body- and eye-movement recordings obtained in freely moving goldfish in different experimental situations are presented. This method would be useful in the recording of eye and gaze movements under natural conditions and for behavioural studies in freely moving animals.

Animals↗
PubMed2001

[Angina pectoris in the heart transplant recipient: evidence of reinnervation].

Heart transplantation involves the removal of a sick heart together with its innervation and replacement with a donor heart isolated from the control of the autonomous nervous system of the recipient, therefore being, functionally dennervated. Dennervation conditions several alterations in cardiac physiology, such as the inability to experience pain during myocardial ischemia, so that theoretically these patients cannot present angina pectoris. However, several reports have shown evidence of reinnervation with isolated cases of transplanted patients with angina pectoris having been reported. We describe the case of a transplanted patient who showed typical effort angina, vascular disease of the graft and data of sympathetic reinnervation demonstrated by cardiac gammagraphy with metayodo-benzilguanidina-I-123.

Angina Pectoris↗
PubMed2001

Successful linkage of medical care and community services for HIV-positive offenders being released from prison.

Human immunodeficiency virus (HIV) infection is more prevalent among the incarcerated than the general population. For many offenders, incarceration is the only time that they may access primary care. Project Bridge is a federally funded demonstration project that provides intensive case management for HIV-positive ex-offenders being released from the Rhode Island state prison to the community. The program is based on collaboration between colocated medical and social work staff. The primary goal of the program is to increase continuity of medical care through social stabilization; it follows a harm reduction philosophy in addressing substance use. Program participants are provided with assistance in accessing a variety of medical and social services. The treatment plan may include the following: mental illness triage and referral, substance abuse assessment and treatment, appointments for HIV and other medical conditions, and referral for assistance to community programs that address basic survival needs. In the first 3 years of this program, 97 offenders were enrolled. Injection drug use was reported by 80% of those enrolled. There were 90% followed for 18 months, 7% moved out of state or died, and 3% were lost to follow-up. Reincarceration happened to 48% at least once. Of those expressing a need, 75% were linked with specialty medical care in the community, and 100% received HIV-related medical services. Of those expressing a need for substance abuse treatment, 67% were successful in keeping appointments for substance abuse treatment within the community. Project Bridge has demonstrated that it is possible to maintain HIV-positive ex-offenders in medical care through the provision of ongoing case management services following prison release. Ex-offenders will access HIV-related health care after release when given adequate support.

Adult↗
PubMed2001

Hodgkin's disease: unsuspected minimal activity in patients that die from causes other than tumoral progression.

Hodgkin's disease (HD) is a curable disease. However, there are still many questions that remain unanswered in this illness, such as the appearance of unsuspected microscopic active illness a long time after the conclusion of treatment, We do not know of any recent publications that have microscopically studied the presence of unsuspected HD activity in patients who died from causes other than tumoral progression. This aspect was analysed in our series of patients with HD. We studied 486 patients with a median follow-up of 8 years. Autopsy was performed in 40 of 144 non-surviving patients. Active HD was found in 60% (24/40) of the patients at autopsy. Of these, 10 patients (25%, 10/40) with active HD died from causes other than tumoral progression. Six patients had minimal clinically unsuspected isolated tumor foci. In spite of technical advances and the introduction of modern and more aggressive chemotherapy, the discovery of minimal unsuspected residual HD continues in an considerable percentage of patients who die from causes other than tumoral progression.

Adolescent↗
PubMed2001

The cost-effectiveness of magnetic resonance imaging for investigation of the knee joint.

OBJECTIVES: This study considered the role of magnetic resonance imaging (MRI) in the diagnosis of knee injuries in a district general hospital (DGH) setting. The principal objective was to identify whether the use of MRI had a major impact on the clinical management of patients presenting with chronic knee problems, in whom surgery was being considered, whether it reduced overall costs and whether it improved patient outcome. In addition, the research: (1) explored the 'diagnostic accuracy' of initial clinical investigation of the knee by an orthopaedic trainee, consultant knee specialist and consultant radiologist; (2) considered the variability and diagnostic accuracy of interpretations of knee MRI investigations between radiologists; (3) measured the strength of preference for the potential diagnostic/therapeutic impact of knee MRI (i.e. the avoidance of surgery). METHODS - RANDOMISED CONTROLLED TRIAL: The research was based on a single-centre randomised controlled trial conducted at Kent and Canterbury Hospital. Patients attending with knee problems in whom surgery was being considered were recruited from routine orthopaedic clinics. Most patients had been referred by their general practitioner. Patients were randomised to either investigation using an MRI scan (MRI trial arm) or investigation using arthroscopy (no-MRI trial arm). The study investigated the benefits of knee MRI at two levels: diagnostic/therapeutic impact (i.e. avoidance of surgery) and patient outcome (using the Short Form with 36 items and EQ-5D quality-of-life measurement instruments). Quality of life was assessed at baseline and at 6 and 12 months. Costs were assessed from the perspectives of the NHS and patients. All analyses were by intention to treat. METHODS - SUBSTUDIES (INVESTIGATION OF DIAGNOSTIC ACCURACY): For the investigation of diagnostic accuracy of initial clinical investigation, the sample comprised 114 patients recruited in a separate study conducted at St Thomas' Hospital. The sample was drawn from patients presenting at the Accident and Emergency Department with an acute knee injury. All study patients received an MRI scan, but initial diagnosis was made without access to the scan or the radiologist's report. After 12 months, all clinical notes and MRI scans of study patients were reviewed and a final 'reference standard' diagnosis for each patient was reached. Comparison was made between the diagnosis recorded by each clinician (i.e. orthopaedic trainee, knee specialist and consultant radiologist) and the reference diagnosis. METHODS - SUBSTUDIES (INVESTIGATION OF THE GENERALISABILITY OF RESULTS): For this substudy, the MRI images from 80 patients (recruited at St Thomas' Hospital) were interpreted independently by seven consultant radiologists at DGHs and the St Thomas' Hospital MRI radiologist. For each area of the knee, the level of agreement (measured using weighted kappa) between the responses of the eight radiologists and the reference standard diagnosis was assessed. METHODS - SUBSTUDIES (INVESTIGATION OF PREFERENCES): The investigation of potential patient preferences for the diagnostic/therapeutic impact of MRI was explored using a discrete choice conjoint measurement research design. Choices involved selecting between two alternative scenarios described using four attributes, and data were collected from 585 undergraduate sports science students and analysed using a random-effects probit model. RESULTS - RANDOMISED CONTROLLED TRIAL: The trial recruited 118 patients (59 randomly allocated to each arm). The two groups were similar in important respects at baseline. The central finding was of no statistically significant differences between groups in all measures of health outcome, although a trend in favour of the no-MRI group was observed. However, the use of MRI was found to be associated with a positive diagnostic/therapeutic impact: a significantly smaller proportion of patients in the MRI group underwent surgery (MRI = 0.41, no-MRI = 0.71; p = 0.001). There was a similar mean overall NHS cost for both groups. RESULTS - SUBSTUDIES (INVESTIGATION OF DIAGNOSTIC ACCURACY): The exploration of diagnostic accuracy found that, when compared to orthopaedic trainees (44% correct diagnoses) or to radiologists reporting an MRI scan (68% correct diagnoses), the accuracy rate was higher for knee specialists (72% correct diagnoses). RESULTS - SUBSTUDIES (INVESTIGATION OF THE GENERALISABILITY OF RESULTS): This generalisability study indicated that, in general terms, radiologists in DGHs provide accurate interpretations of knee MRI images that are similar to a radiologist at a specialist centre. The one area of the knee for which this did not hold was the lateral collateral ligament. RESULTS - SUBSTUDIES (INVESTIGATION OF PREFERENCES): The central finding for this substudy was that, on average and within the range specified, choices in this group of potential patients were not significantly influenced by variation in the chance of avoiding surgery. CONCLUSIONS - IMPLICATIONS FOR HEALTHCARE: The evidence presented in this report supports the conclusions that the use of MRI in patients presenting at DGHs with chronic knee problems in whom arthroscopy was being considered did not increase NHS costs overall, was not associated with significantly worse outcomes and avoided surgery in a significant proportion of patients. CONCLUSIONS - RECOMMENDATIONS FOR FURTHER RESEARCH (IN PRIORITY ORDER): (1) The trial data demonstrated that the use of MRI in patients with chronic knee problems reduced the need for surgery. However, the link between diagnostic processes and changes in health outcome is indirect and the finding of no-MRI-related effect on health outcome may, therefore, be a consequence of the limited power of the trial. Further research to confirm (or contradict) these findings would be valuable. (2) The investigation of diagnostic accuracy involved comparison with a reference diagnosis established by a panel of two clinical members of the research team. It would be interesting to explore the extent to which the results would differ using an external panel. (3) The result from the preference study, indicating that the potential diagnostic/therapeutic impact of knee MRI was not highly valued, is a surprising finding that would be important to explore in general public or patient populations. (4) The focus for the trial-based aspects of this research was the DGH and patients presenting with chronic knee problems who were being considered for surgery. Care should be taken in generalising from these results to other patient groups (e.g. acute knee injuries) or to other settings (e.g. specialist centres). Further clinical trials would be required in order to answer such questions.

Adolescent↗