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Biomedical subjects

R Sutton

Publications and source records attributed to R Sutton.

At least 109 records · Page 6Linked to original sources
PubMed1994

Endogenous phosphorylation of tau proteins in brain slices.

Tau protein phosphorylation has been implicated as a main process that regulates microtubule dynamics. A large number of tau isoforms is generated by phosphorylation through the action of a diversity of kinases. We have analysed variations in tau phosphorylation by two-dimensional gel electrophoresis, where a great heterogeneity of isoforms can be detected. Using mouse brain slices from various developmental stages we have found preferential phosphorylation of low molecular weight tau isoforms in all the ages analysed. A greater isoform diversity was found in juvenile than in adult brain. Brain slices provide a tightly regulated environment that preserves cell compartmentalization and has shown to be very useful for studies on tau phosphorylation.

Animals↗
PubMed1994

Plasminogen activator inhibitor-1 in the cerebrospinal fluid as an index of neurological disease.

Plasminogen activator inhibitor-1 (PAI-1) is a serpin proteinase inhibitor which regulates fibrinolysis and the proteinase cascade of tumour invasion. In this study, PAI-1 was identified in the cerebrospinal fluid (CSF) from patients without neurological disease and patients with various neurological disorders. The mean level of PAI-1 in the CSF of 28 patients without central nervous system (CNS) disease was 0.28 +/- 0.03 (SEM) ng/ml. CSF PAI-1 was significantly increased in the following diagnostic categories:dementia (Alzheimer's disease), cerebral infarction, CNS infection, alcohol withdrawal seizures and CNS neoplasia. In all these disorders, with the exception of CNS infection, PAI-1 was also increased as a fraction of total CSF protein. CSF PAI-1 was not increased in patients with hydrocephalus or idiopathic seizure disorders. Complementary plasma samples were available for 18 of the 128 CSF specimens studied. For these cases, there was no correlation between plasma PAI-1 and CSF PAI-1 levels. PAI-1 may represent a non-specific marker of disease in the central nervous system.

Adolescent↗
PubMed1994

Incidence of complications after carotid sinus massage in older patients with syncope.

OBJECTIVE: To review the incidence of neurological complications occurring after carotid sinus massage performed for diagnostic purposes. DESIGN: Case review and comparison with previously published work. SETTING: Syncope Clinic, Royal Victoria Infirmary, Newcastle-upon-Tyne, and Chelsea and Westminster Hospital, London. PARTICIPANTS: Patients undergoing investigation of dizziness, syncope, or unexplained falls. METHODS: Carotid sinus massage performed for 5 seconds in both supine and erect postures, both before and after atropine. Contraindications to carotid sinus massage were the presence of carotid bruits, recent myocardial or cerebral ischemia, or previous ventricular tachyarrhythmias. RESULTS: Two cases of neurological complications were reported from a total of 500 patients (2000 massage episodes) investigated in one center, giving an incidence of 0.1%. Combining this data with another center performing investigations in a similar fashion, seven neurological complications arose from a total of 5000 massage episodes, an incidence of 0.14%. Reported complications were pyramidal signs in five cases and visual field defects in two. Pyramidal weakness persisted in one case with a pre-existing stroke on the same side, and a visual field loss was permanent in one. CONCLUSIONS: Neurological complications following carotid sinus massage for diagnosis of the carotid sinus syndrome are uncommon and usually transient. Contraindications to carotid sinus massage should be respected and the standardized technique used.

Aged↗
PubMed1994

Short AV interval VDD pacing does not prevent tilt induced vasovagal syncope in patients with cardioinhibitory vasovagal syndrome.

Eleven subjects (mean age 50 years, range 33-71 years), who had previously received permanent dual chamber pacemakers for cardioinhibitory vasovagal syncope, underwent paired Westminster protocol tilt tests, one with short AV delay VDD pacing and one without pacing, to test the hypothesis that continuous ventricular pacing would prevent the cardiac initiation of vasovagal syncope. Nine (82%) of the paced tilts produced positive vasovagal outcomes compared with seven (64%) of the unpaced tilts. No important differences in the heart rate or blood pressure behavior during tilt or the time to positive vasovagal outcomes were observed between the paired tilts. There was more accelerated syncope/presyncope once symptoms had developed during the paced tilts of subjects in whom both study tilts were positive, although this did not reach statistical significance (P = 0.054). This study shows that atrial synchronous ventricular pacing does not prevent the initiation, or progression, of tilt induced vasovagal syncope in predisposed subjects.

Adult↗
PubMed1994

Reasons for reprogramming dual chamber pacemakers to VVI mode: a retrospective review using a computer database.

Seven hundred seventy-one dual chamber pacemakers implanted over a 13-year period were identified using a computer database. The mean follow-up period was 40.4 +/- 30.9 months (mean +/- SD). Thirty-three (4.3%) patients were reprogrammed to the VVI mode after a mean period of 26.4 +/- 29 months. Indications for pacing in those reprogrammed were: complete heart block 45.7%, impaired AV conduction 5.7%, sick sinus syndrome 34.2%, carotid sinus syndrome 11.4%, and vasovagal syndrome 2.8%. The most common reason for reprogramming was development of sustained atrial arrhythmias (atrial fibrillation or flutter), which occurred in 25 patients (3.3% of entire group). The remaining 8 (1% of entire group) were reprogrammed because of atrial lead related problems.

Arrhythmias, Cardiac↗
PubMed1994

Crohn's disease and myasthenia gravis: a possible role for thymectomy.

A female patient with a three year history of Crohn's disease of the colon developed myasthenia gravis. Despite diversion of the faecal stream by an ileostomy, and total colectomy, the patient had continuing problems with perineal and perianal abscesses and fistulas. Her myasthenia gravis became unresponsive to anti-cholinergics so a thymectomy was performed. The perineal and perianal disease improved subsequently. This case supports the theory that functional disturbances of the thymus may have a role in the pathogenesis of inflammatory bowel disease.

Adult↗
PubMed1994

Permanent pacing for cardioinhibitory malignant vasovagal syndrome.

OBJECTIVE: To evaluate the effect of permanent pacing in cardioinhibitory malignant vasovagal syndrome. PATIENTS AND METHODS: 37 patients with permanent pacemakers for cardioinhibitory malignant vasovagal syndrome. All presented with syncope (median six episodes, median frequency two episodes a year) and after conventional investigation and invasive electrophysiological assessment they remained undiagnosed, and without a generally accepted indication for pacemaker implantation. In all vasovagal syncope with cardioinhibition (heart rate at syncope < 60 beats/min) developed during tilt tests performed according to the Westminster protocol (head up tilt at 60 degrees with a footplate support for 45 minutes or until syncope intervenes). Dual chamber pacemakers were implanted in 35 (95%) and VVI pacemakers in the remaining two (5%). RESULTS: Over a mean (SD) follow up since implantation of 50.2 (23.9) months symptomatic improvement occurred in 89%: 62% remained free of syncope and 27% were completely symptom free. The collective syncopal burden of these 37 patients was reduced from 136 to 11 episodes each year. During follow up three patients died from unrelated causes. Patients who become asystolic during the tilt test (sinus pause of at least four seconds) experienced no greater benefit from pacing than those with less extreme cardioinhibition. Patients who remained free of syncope since implantation were younger than those who continued to experience syncope. Patients who remained completely symptom free after implantation were younger, more likely to be male, and had had fewer syncopal episodes before implantation than those who continued to experience syncope or presyncope. No other demographic, clinical, investigative, or pacing variable suggested a more favourable outcome after implant. CONCLUSIONS: This retrospective and uncontrolled experience suggests a possible role for permanent pacing in selected patients with cardioinhibitory malignant vasovagal syndrome. Improved acquisition of tilt test data may enable better selection of patients who are suitable for permanent pacing. A randomised prospective study to compare permanent pacing with no treatment or with medical treatment in cardioinhibitory malignant vasovagal syndrome is indicated.

Adult↗
PubMed1994

Evaluation of a rapid infusion system.

Operative cases where there is a potential for massive blood loss necessitates a system to rapidly warm and transfuse large volumes of blood over short periods of time. An in-house system in which both crystalloid solutions and blood products can be quickly added, warmed and available for infusion was developed to meet this need. The purpose of this study was to evaluate how blood products are affected when warmed and recirculated for an extended period of time. A recirculating rapid infusion system was assembled utilizing two filtered cardiotomy reservoirs, a centrifugal pump, a stainless steel blood heat exchanger, and 1/4 inch tubing, and applied in six adult orthotopic liver transplantations. The system was primed with 2 to 4 units each of fresh frozen plasma and packed red blood cells. The prime was recirculated and warmed to 37 degrees C. Samples for blood gases, oxygen saturation, hematocrit, plasma free hemoglobin, sodium and potassium levels were drawn after initial priming and then every 30 minutes until additional blood products were added. Results show no significant change in pH (6.57 +/- 0.21), pO2 (56 mmHg +/- 23 mmHg), pCO2 (173 mmHg +/- 138 mmHg), hematocrit (27% +/- 8.7%) and plasma free hemoglobin values (125 mg/dl +/- 9.4 mg/dl), following 3 hours of recirculation. However, potassium levels significantly decreased from 11.6 meq/L +/- 2.6 meq/L to 10.0 meq/L +/- 2.3 meq/L (p < 0.05), sodium levels significantly increased from 144 meq/L +/- 5.9 meq/L to 147 meq/L +/- 5.3 meq/L (p < 0.05) and oxygen saturations significantly increased from 59% +/- 9.1% to 70% +/- 16% (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Analysis↗
PubMed1993

Vasovagal reactions may occur after orthotopic heart transplantation.

OBJECTIVES: This study evaluated the ability of patients to manifest vasovagal reactions after orthotopic heart transplantation. BACKGROUND: Paradoxic stimulation of left ventricular baroreceptors may be the afferent limb of the vasovagal reflex in humans. Orthotopic heart transplantation causes surgical denervation of these receptors and would therefore be expected to abolish the vasovagal reflex. METHODS: To attempt to confirm this hypothesis, 10 patients with orthotopic heart transplantation underwent both head-up tilt testing while resting on a saddle support and testing for parasympathetic innervation of the donor heart before and after atropine infusion. Native and donor heart sinus rates were monitored by using an esophageal pill electrode throughout tilting and during parasympathetic testing. RESULTS: Unexpectedly, seven patients had vasovagal responses at saddle support tilt testing, during which native heart rate decreased by 25 +/- 7 beats/min and mean arterial blood pressure decreased by 55 +/- 9 mm Hg. In three of these patients, there was also a decrease in donor heart rate of 23 +/- 26 beats/min. Parasympathetic testing showed possible evidence of donor heart vagal reinnervation in these patients with donor heart bradycardia during tilt but not in those with vasovagal reactions to tilt without slowing of the donor heart rate. CONCLUSIONS: Vagal efferent reinnervation can occur after orthotopic heart transplantation in humans. However, the absence of such reinnervation in some patients with vasovagal responses to tilt calls into question the role of left ventricular receptors in inducing the vasovagal reaction.

Adolescent↗
PubMed1993

Cardiac pacing.

The symptom most frequently requiring investigation and consideration for cardiac pacing is syncope. This symptom is now receiving more attention than ever, mainly because of the advent of tilt table testing--a simple noninvasive procedure that has substantially reduced the number of syncopal patients remaining undiagnosed. The first part of this review addresses developments in the understanding of syncope, and the latter part covers developments in the understanding and therapy of atrioventricular block and sinus node disease, the management of carotid sinus syndrome, and two possible new indications for pacemaker therapy.

Arrhythmias, Cardiac↗