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Biomedical subjects

A Robles

Publications and source records attributed to A Robles.

At least 73 records · Page 4Linked to original sources
PubMed1985

Long-term assessment of aortic valve replacement with autologous pulmonary valve.

Two hundred two autologous pulmonary valves were transplanted into the aortic position between 1967 and 1982 at the National Heart Hospital in London. The indication for operation was congenital or acquired aortic valve disease, and the patients were followed for periods from 1 to 4 years. The patients were not anti-coagulated, but the entire series has been completely free from thromboembolism or bleeding. The actuarial prediction of freedom from valve-related deaths was 82 +/- 6% at the end of the fourteenth year after operation; deaths were due to reoperations for technical failure and to infective endocarditis. Event-free survival of the autologous pulmonary valve in the aortic position was 73 +/- 6% after 14 years at risk. Valve failure resulted mainly from technical problems encountered during the early years of surgical experience. There was no macroscopic or histological evidence of calcification in any of the failed valves. The right ventricular outflow was reconstructed with an aortic homograft in the majority of patients; 81 +/- 5% of these homografts demonstrated event-free performance over a 12-year follow-up period. It is concluded that the long-term performance of a pulmonary autograft inserted for aortic valve disease is superior to that of any other valve substitute and that the operation offers an almost ideal means of aortic valve replacement in appropriate patients.

Adolescent↗
PubMed1984

Regulation of phosphoprotein phosphatase by somatostatin.

Cyclic somatostatin inhibited phosphoprotein phosphatase activity in rat liver slices, as well as a partially purified phosphoprotein phosphatase from rat liver. This change was accompanied by a concomitant decrease in cyclic AMP-dependent protein kinase. Studies in vivo showed similar trends in the variation of both enzymes.

Animals↗
PubMed1984

Effects of substance P on acetylcholinesterase activity.

The effects of substance P on acetylcholinesterase activity have been examined. The neuropeptide produced a significant increase in the activity of the enzyme in rat cerebral cortex. Pretreatment of rats with either actinomycin-D or cycloheximide did not fully abolish the substance P-mediated stimulation of cerebral acetylcholinesterase. Substance P increased the enzyme activity in rat brain slices; moreover, substance P increased the activity of electric eel acetylcholinesterase in in vitro experiments. These observations indicate that substance P produces an induction of acetylcholinesterase in cerebral cortex of rats and in addition indicate that a direct action on the enzyme takes place.

Acetylcholinesterase↗
PubMed1984

Surgical treatment of prosthetic endocarditis. Aortic root replacement using a homograft.

This article reports the successful surgical treatment of six patients who presented with prosthetic endocarditis and uncontrolled bacteremia. They were treated by replacement of the aortic root with a preserved homograft aortic valve. With this technique, ventricular-aortic continuity was established with a centrally flowing valve together with its attached aorta. The weakened aortic and the associated root abscess were thereby excluded from the high-anulus pressure systemic circulation. There were no operative deaths, and the longest postoperative survival time is 10 years. Two patients have conduction disturbance and symptoms relating to their malfunctioning aortic valves. The remaining four patients are all well at 5 years, 2 years, 9 months, and 6 months with no further evidence of infection. Homograft aortic root replacement is a suitable treatment for this potentially lethal condition.

Adolescent↗
PubMed1981

Clinical experience with the Carpentier-Edwards porcine xenograft.

The first 101 patients to undergo aortic, mitral or double valve replacement with a Carpentier-Edwards bioprosthesis at the National Heart Hospital are reviewed. A total of 112 valves were replaced (69 aortic, 43 mitral), with an operative mortality of 12.9%. The 88 operative survivors were followed for up to 52 months. There were 9 thromboembolic episodes (3.9% per patient year), most of which were not confined to the early postoperative months. They were most common after mitral valve replacement (6.3% per patient year), particularly in the presence of atrial fibrillation. A low incidence of prosthetic endocarditis was noted, principally involving the valve in the aortic position. Three valves were removed for calcific degeneration and small structural defects were noted incidentally in 3 valves removed for other reasons. The possible etiology and significance of these is discussed. Seven of the 10 reoperations and 5 of the 9 late deaths were considered to be xenograft-related. Over a 4-year follow-up period there was a 9% incidence of valve-related deaths, an overall survival of 87% and a complication-free survival of 73%.

Adolescent↗
PubMedDate not supplied

A randomized double-blind clinical trial of two antivenoms in patients bitten by Bothrops atrox in Colombia. The Regional Group on Antivenom Therapy Research (REGATHER).

A randomized double-blind clinical trial in 39 patients envenomed by Bothrops atrox in Antioquia and Chocó, Colombia, was performed to compare the efficacy and safety of 2 equine-derived antivenoms prepared at Instituto Clodomiro Picado, University of Costa Rica. Twenty patients received a monovalent anti-B. atrox antivenom (group A) and 19 patients were treated with a polyvalent (Crotalinae) antivenom (group B). Both antivenoms were equally efficient in the neutralization of the most relevant signs of envenoming (haemorrhage and blood clotting time alteration). Fourteen patients (36%) presented early adverse reactions to antivenoms and no significant difference between the 2 groups was observed. Urticaria (18%) was the most frequent early adverse reaction and there was no life-threatening anaphylactic reaction. Based on clinical criteria and serum venom levels, estimated by an enzyme immunoassay, 15 patients were classified into 2 groups: mild and moderate/severe envenoming. With the antivenom doses used in this study (3, 6 and 9 vials for mild, moderate and severe envenoming, respectively), both antivenoms were equally efficient in clearing serum venom levels within the first hour of treatment, and the levels remained below the lower limit of venom detection for 24 h. Antivenom concentration in serum remained high for up to 24 h after antivenom infusion, suggesting that an excess of antibody in relation to circulating antigen had been administered.

Adolescent↗
PubMedDate not supplied

Functional analysis of aberrant behavior maintained by automatic reinforcement: assessments of specific sensory reinforcers.

The purpose of this study was to develop a systematic functional assessment package for aberrant behaviors maintained by nonsocial (automatic) reinforcement. The assessment package included four components: (1) functional analysis, (2) antecedent assessment of specific automatic reinforcement sources, (3) stimulus preference assessment, and (4) treatment evaluation. Functional analysis data indicated automatic reinforcement functions of the stereotypy exhibited by a 10-year-old male and the self-injury (SIB) exhibited by a 30-year-old male. Antecedent assessments of sensory classes indicated that auditory stimulation and tactile stimulation were associated with stereotypy and SIB, respectively. A multiple-stimulus-without-replacement procedure was conducted with each participant to identify the most- and least-preferred stimuli within the identified sensory classes. In an attempt to validate the assessment package for each participant, a DRO procedure was implemented using a reversal design with a multielement component. DRO procedures using stimuli within the targeted sensory classes were successful in eliminating the aberrant behaviors of both participants. The results are discussed in the context of improving the methodology for assessing and treating automatically reinforced behaviors.

Adult↗
PubMedDate not supplied

[Lewy bodies dementia: new data for the understanding of neuroimaging].

INTRODUCTION: The criteria for diagnosis of dementia with Lewy bodies (DLB) do not include neuroimaging, and few reports have been published on this. OBJECTIVE: To report our observations of cerebral CAT and MR studies in 25 patients with probable DLB. PATIENTS AND METHODS: Measurement of the surface of the cerebral lobes and the hippocampal region in two axial sections on CAT and MR and three coronal sections on MR. Our controls were 27 persons with probable Alzheimer's disease and 30 healthy persons of the same age group. RESULTS: The size of the frontal, parietal and temporal lobes in DLB is intermediate between the values found in Alzheimer's disease and those found in asymptomatic persons, but without significant differences from these. Atrophy of the hippocampal region seen in DLB is significant as compared with healthy persons, but not when compared with those with Alzheimer's disease, in whom it was greater still. In the patients in whom DLB was still not an advanced stage, there was no atrophy of the occipital lobes, in spite of other observers having found hypoactivity of these lobes on SPECT and PET. CONCLUSION: In the sample studied, structural imaging techniques were not useful in the diagnosis of DLB.

Aged↗
PubMedDate not supplied

The tropicamide test in patients with dementia of Alzheimer type and frontotemporal dementia.

The tropicamide test was applied to 30 patients with probable Alzheimer's disease (pAD), 12 with frontotemporal dementia (FTD) and 46 healthy subjects. One drop of 0.01% tropicamide was instilled in one eye and one drop of saline solution in the other. The pupil diameter was measured with a Goldmann pupillometer in its basal condition and 10, 15, 20, 25, 30, 35, 45 and 55 minutes afterwards. The results do not show differences between pupil dilation observed in pAD and in FTD; in both groups, from the beginning of the test, the pupil dilated more than in healthy people. A high interindividual variability was observed. The best cutoff point is 38% of interpupillary difference at minute 25 (sensitivity = 63%, specificity = 80%). If we consider the prevalence of AD in a population over 40 years old to be 1.4%, the adjusted positive predictive value of the test would be 4.2%. According to these results, the test is not a true diagnostic marker of AD.

Adult↗
PubMedDate not supplied

[A controlled, double-blind, randomized pilot clinical trial of nicardipine as compared with a placebo in patients with moderate or severe head injury].

INTRODUCTION: One of the factors involved in the occurrence of ischemic cerebral lesions following head injury is cerebral vasospasm. We analyze the effect of intravenous nicardipine on the prevention and treatment of posttraumatic cerebral vasospasm. PATIENTS AND METHODS: We made a placebo-controlled, randomised, double-blind pilot study of the effect of nicardipine (intravenously 5 mg/hour for one week) on patients with moderate or severe head injury who presented with cerebral vasospasm, defined as an average Doppler flow velocity (DFV) of 100 cm/second or more. The main variable assessed was the evolution of the DFV and the secondary criteria were the evolution of the arterial blood pressure, coma scales, the findings on the Glasgow Coma Scale and the safety of the drug. RESULTS: Eleven patients were included in each homogeneous group. The DFV was found to have become normal on the first day of treatment with nicardipine and on the third day with the placebo (p = 0.023). During the first day of treatment the percentage of cerebral hemispheres diagnosed as having suspected spasm was 11.1% for nicardipine and 64.3% for the placebo (p = 0.02881). The average time for recovery (DFV < 100 cm/second) was 3.33 days with the placebo and 1.22 days with nicardipine (p = 0.0039). The patients treated with nicardipine had 8.89 times more chance of recovery from vasospasm. The incidence of adverse effects was greater with the placebo (p = 0.014). CONCLUSION: Nicardipine is effective in the reversal and prevention of increased Doppler flow velocity in patients with moderate or severe head injury.

Adult↗
PubMedDate not supplied

[Lewy body dementia: some contributions to the clinical knowledge].

INTRODUCTION: Dementia with Lewy bodies is the second commonest type of dementia. The latest criteria for its diagnosis have recently been established (1996). PATIENTS AND METHODS: We report the clinical findings in 25 patients with probable dementia with Lewy bodies. RESULTS: No sex predominance was seen, onset was after the age of 65 years in 60% of the cases and there was a past history of dementia in 48%. Onset was with cognitive disturbances in 32%, Parkinsonism in 32% and both in 32%. When there was an interval between Parkinsonism and dementia, this was of 3-19 months. The dementia included attention disorder, impaired recall and praxis alterations. Disorders of executive function, behaviour or language, were seen in two thirds of the patients and acalculia in over half. Around 50% showed signs of subcortical involvement different from Parkinsonism. Parkinsonism was basically hypokinetic (96%), with tremor in two thirds of the cases, at rest (29%) postural (12%) or combined (59%), and symmetrical in 41%. Rigidity was only seen in 52% and was slight in most cases. In 16% there was weakness of vertical gaze. In 40% urine or double incontinence occurred, mainly when the dementia was at an intermediate or advanced state. CONCLUSIONS: Dementia with Lewy bodies is a dementia with fronto-temporo-parietal alterations, frequently associated with hypokinetic Parkinsonism (which always shows a lag period with respect to dementia of less than 24 months), hallucinations and a fluctuating course. Other findings supporting this diagnosis were seen in two out of every three patients.

Aged↗
PubMedDate not supplied

Laparoscopic-assisted lumboperitoneal shunt: a simplified technique.

OBJECTIVES: Lumboperitoneal shunt has been advocated as a better alternative to ventriculoperitoneal shunt in communicating hydrocephalus. To minimize the morbidity of subcutaneous tunneling or an open abdominal wound, we developed a simplified technique for laparoscopy-assisted placement of lumboperitoneal shunts. METHODS: Patients deemed candidates for lumboperitoneal shunts underwent laparoscopy-assisted lumboperitoneal shunt placement. Using a Tuohy needle, the neurosurgeon obtains access to the lumbar subthecal space. Simultaneously, the laparoscopist obtains access to the peritoneal cavity with two 5-mm ports for the take down of the descending colon, clearing the way for the passage of the shunt passer from the back into the peritoneal cavity. RESULTS: Over the last 5 years, 45 patients have undergone laparoscopy-assisted lumboperitoneal shunt placement. Patients have been followed with neuropsychiatric examinations, imaging studies, and repeated neurological examinations. No complications related to the laparoscopy have occurred. Neurosurgical complications included postural headaches caused by overdrainage in 4 patients requiring laparoscopic modification of the shunt slit and in 1 patient with acquired Arnold-Chiari I malformation. CONCLUSION: Laparoscopy-assisted lumboperitoneal shunt offers many advantages over percutaneous ventriculoperitoneal or laparoscopic transabdominal lumboperitoneal shunts. The procedure can be performed in less than 30 minutes by any practicing laparoscopist.

Cerebrospinal Fluid Shunts↗
PubMedDate not supplied

Left ventricular fibroma: echocardiographic diagnosis and successful surgical excision in three cases.

The management of three patients with left ventricular fibromas is outlined. All were asymptomatic children. Routine chest radiography suggested cardiac masses. M-mode and two-dimensional echocardiography were valuable adjuncts to conventional angiography in assessing these children. Electrocardiographic changes, present in all cases, were shown to regress postoperatively. We stress the importance of these noninvasive aids in the initial investigation and outline our operative methods of reconstruction.

Child↗
PubMedDate not supplied

[Acute ischemia of lower limb and long-term treatment with epidural bupivacaine].

We report the treatment of an ischemic lower limb (arterial obstruction shown by angiography at popliteal level, proximal to common tibioperoneal artery) with 0.125% and 0.20% epidural bupivacaine, which was continuously administered by pump during 30 days. Simultaneously, 8 mg morphine chloride was administered every 24 hours by epidural route, anticoagulation with heparin was started, and transcutaneous electrical stimulation was used. The favorable outcome, with sufficient peripheral revascularization, permitted to preserve the limb. During therapy no sign of cardiac toxicity attributable to bupivacaine was detected.

Adult↗