Biomedical subjects
Publications and source records attributed to R Vincent.
This paper traces the impact of the Rome Treaty of March 1957 on the countries of the European Economic Community relative to dental education. It also reviews the studies that have been conducted to help determine how best to implement the freedom of movement of dentists throughout the Community.
Seven of 475 consecutive patients treated with thrombolysis for acute myocardial infarction had severe embolic complications that were believed to be caused by disintegration of pre-existing clot. Three patients had symptoms that persisted for many weeks, and five died. Any potential site of pre-existing blood clot within the vascular system, notably an enlarged left atrium, ventricular aneurysm, or aortic aneurysms, should be regarded as a contraindication to treatment with thrombolytic agents.
The evolution of surface ventricular late potential activity was studied in 50 patients during the 6 weeks after first acute myocardial infarction (AMI). In 15 of 47 patients (32%) late potential activity appeared within 6 hours of the onset of major symptoms. Its prevalence overall remained approximately 30% at each recording time but with marked individual variability in appearance. Late potential activity was associated with late ventricular arrhythmias (greater than 24 hours after AMI) but not with early ventricular arrhythmias (less than 24 hours after AMI). Late ventricular arrhythmias or sudden death occurred only in the 6 patients with late potential activity (p less than 0.05). Early ventricular fibrillation (15 patients) occurred equally in the patients with and without late potential activity. Thus, late potential activity occurs at some stage in the first 6 weeks after AMI in 50% of patients, but its timing is variable. It is a sensitive but not specific predictor of late ventricular arrhythmias and sudden death, but not of early ventricular fibrillation.
The techniques required to record standard convergent beam electron diffraction patterns in an analytical electron microscope are discussed in detail, with emphasis on the design of electron optics in commercial instruments. Practical comments are included on specimen preparation, the influence of crystal defects, tilting to major zone axes, and alignment of the instrument. The influence of parameters under experimental control such as probe size, accelerating voltage, temperature, specimen thickness, and convergence angle is discussed in detail. Some comments are included on the alignment and limitations of large angle patterns formed by a defocused probe.
In order to identify sensitive and specific biochemical indicators of pulmonary damages caused by industrial contaminants, male Long-Evans rats were exposed to a cadmium chloride (CdCl2) aerosol (5 mg Cd/m3; MMAD = 1.4 microns; SDg = 1.8) for 1 hr. The rats were sacrificed at 1, 4, 8, and 16 days after treatment. The response of the pulmonary surfactant (SF) system, which prevents alveolar collapse during expiration by lowering the surface tension at the air-liquid interface, was of particular interest. The effect of CdCl2 inhalation on the SF system was monitored by assaying the alkaline phosphatase (AKP) activity and phospholipid (PL) content in an enriched surface active SF fraction purified from bronchoalveolar lavages. The AKP activity of the SF fraction was markedly decreased (99%) on Day 1, indicating an inhibition of AKP by Cd. The PL content remained at control level while the total protein content was significantly increased (199%). On day 4, the high recovery of PL (207%) and AKP activities (639%) may reflect an increased secretion caused by Type II cell hyperplasia. By Day 8 these parameters returned to baseline levels. On Day 16 both the AKP activity and the PL content of the SF fraction were decreased significantly. Concurrently, the activities of the acid phosphatase and the B-N-acetylglucosaminidase followed, but to a lesser extent, the response of the AKP activity on Days 1 and 4. They differed from AKP, however, in that their activities remained significantly elevated on Day 8 and in that they returned to baseline levels on Day 16.(ABSTRACT TRUNCATED AT 250 WORDS)
A 13 year old girl with recurrent ventricular tachycardia that occurred in association with anomalous origin of the left coronary artery from the pulmonary artery is described. Such an arrhythmia has not been described before. Ligation of the anomalous left coronary artery led to more frequent episodes of ventricular tachycardia with evidence of myocardial ischaemia. She was successfully managed by revascularisation (to establish a two coronary system) and map-guided left ventricular aneurysmectomy.
1. Blood glucose concentration, glucose turnover and gas exchange were monitored in adult male domestic fowl at rest and during 90 min of continuous treadmill exercise. 2. During exercise oxygen consumption increased to about three times its resting value. Blood glucose concentration fell by 26% by the end of exercise. 3. Blood glucose turnover was not altered by exercise and oxidation showed only a moderate increase (35%). Glucose oxidation accounted for 23% of the total energy expenditure at rest and this value fell to 10% during exercise. At the same time the plasma free fatty acid concentration rose to three times its resting value suggesting an increased mobilisation of this substrate. 4. It is concluded that during exercise of this relatively moderate intensity glucose is a quantitatively minor fuel for the working muscles.
1. Plasma free fatty acid (FFA) concentration, FFA turnover and gas exchange were measured in adult male domestic fowl at rest and during 90 min continuous treadmill exercise at a work load of approximately three times the resting metabolic rate. 2. Plasma FFA concentration and turnover increased 7-fold and 4-fold respectively during exercise. Of the FFA turnover 0.54 was oxidised at rest and this increased to 0.70 during exercise. The fraction of the total carbon dioxide production derived from plasma FFA oxidation rose from 0.33 at rest to 0.55 during exercise. 3. It is concluded that plasma FFA are the most important source of energy for the working muscles of domestic fowl during treadmill exercise of this intensity and duration.
1. The effects of 90 min continuous treadmill exercise on the plasma-to-ovary transfer of 14C-labelled triglycerides in laying hens were examined. 2. Exercised birds showed a 4-fold increase in plasma free fatty acid concentration, a 15% decrease in plasma glucose concentration and unchanged plasma triglyceride concentration compared with resting controls. The mean plasma-to-ovary triglyceride transfer rate was approximately halved by exercise. 3. The surface area-specific triglyceride transfer rate was greatest for oocytes weighing 0.25-1.5 g and decreased with increasing oocyte size. The lowest rates were in the small (less than 0.25 g) white oocytes. This pattern was largely unaffected by exercise. 4. Factors that might be responsible for the reduction in triglyceride transfer into the oocytes during exercise include hormonal effects on the permeability of the oocyte envelope, increased competition for plasma lipids by the working muscles and reduced blood flow to the ovary, as a result of the release of vasoconstrictors.
In order to establish an animal model for assessing early and sensitive biochemical indicators of pulmonary damage, we studied the effects of inhaled CdCl2 (5 mg/m3.h; mass median aerodynamic diameter (MMAD) = 1.4 microns; SDg = 1.8) on the antioxidant defense and pulmonary surfactant systems of rat lungs. Rats were sacrificed 1, 4, 8, and 16 d after inhalation. Pulmonary edema (wet/dry weight) was observed on d 1. The total activities of the enzymes superoxide dismutase (SOD) and glucose-6-phosphate dehydrogenase (G6PD) in the lung homogenates of the treated animals were significantly throughout the 16-d period. Glutathione reductase (GR) was increased on d 4 and after. The general increases of SOD, GR, and the lysosomal enzymes acid phosphatase and beta-N-acetylglucosaminidase could be attributed to changes in the cellularity of the lung tissue. The significant increase in the specific activity of G6PD on d 4 suggested enzyme stimulation. Concurrently, the response of the surfactant system was measured by assaying the alkaline phosphatase (AKP) and the phospholipid content in the homogenates and in the cell-free bronchoalveolar lavage (BAL) fluids. The AKP activity in the homogenates decreased by 30%, while no activity was detected in the BAL on d 1, suggesting an inhibition of AKP by Cd. The secretion of surfactant seemed altered at this early time: phospholipid in the BAL decreased by 44%, although it increased by 61% in the tissue. The high recovery of phospholipid (312%) in the BAL on d 4 and the important changes in the AKP activity in the BAL from d 4 to 16 may reflect alterations in the processing of the surfactant. The effect of Cd on AKP makes this enzyme a potential marker of the metal redistribution in the pulmonary alveolar region, which could be a useful tool in long-term studies.
A consecutive series of 559 hospital survivors of acute myocardial infarction aged less than 66 years were studied; 93 were designated prospectively as low-risk because they were suitable for early submaximal exercise testing and had none of the following clinical or exercise test 'risk factors': (1) angina for at least one month prior to infarction; (2) symptomatic ventricular arrhythmias, or (3) recurrent ischaemic pain, both after the first 24 h of infarction; (4) cardiac failure; (5) cardiomegaly; and (6) an abnormal exercise test (angina, ST-depression or poor blood pressure response). Altogether 301 patients were exercised; their mortality over a median follow-up of 2.4 years was 10.2%, versus 24.6% in the 258 patients not exercised (P = 0.0005). Absence of clinical 'risk factors' alone, in the exercised patients, identified 156 with a mortality of 5.4% versus 15.6% in the 145 with at least one clinical 'risk factor' (P = 0.004). The fully defined low-risk group comprised 93 of the former patients who had neither clinical nor exercise test 'risk factors'. None of these patients died compared with 19 of those with at least one 'risk factor' (mortality = 14.7%; P = 0.002). Their respective rates of non-fatal reinfarction were similar and never exceeded 5% per annum. Therefore, simple clinical and exercise test criteria can positively identify low-risk patients after infarction in whom secondary prevention may be inappropriate.
Transcutaneous cardiac pacing using the Pace-Aid (Cardiac Resuscitator Corporation) was assessed in 32 emergency patients presenting with profound bradycardia or asystole who had failed to recover with advanced life support including the use of epinephrine. Pacing stimuli, pulse width 20 ms at 50, 100, or 200 mA, were delivered through two 8 cm gel-pad electrodes placed antero-posteriorly on the chest. By ECG criteria, definite electrical capture was achieved in a total of five patients and possible capture in a further 16. Of the 21 patients presenting in asystole 11 showed possible electrical capture only. No evidence of capture was seen in one third of the patients studied. Use of the Pace-Aid resulted in a palpable pulse in a total of seven patients. Four of the 11 patients with profound bradycardia survived to receive temporary transvenous pacing; two were eventually discharged. None in the asystolic group survived. Difficulties in using the Pace-Aid resulted from electrical overload by the pacing impulse that obscured the evidence for electrical capture, and intense muscle contraction that hindered reliable palpation of the arterial pulse. Transcutaneous pacing can occasionally be of value even at a late stage in the emergency treatment of profound bradycardia but is unlikely to be worthwhile in complete asystole.
Vasculitis developed in six of 253 patients treated with intravenous anisoylated plasminogen streptokinase activator complex (APSAC) after acute myocardial infarction. All patients recovered spontaneously with no evidence of renal impairment and no long term sequelae. Although leucocytoclastic vasculitis and serum sickness have been reported after streptokinase treatment, such allergic reactions have not been described as a complication of other thrombolytic agents.
Bar-like structures are tubular cytoplasmic inclusions found in situ in pulmonary epithelial type II cells of several animal species. The physiological significance and mode of formation of these inclusions are not fully established. In this paper, we describe bar-like structures as found in freshly isolated type II cells from rat lungs. Pulmonary cells were dissociated from the tissue with elastase and separated on a discontinuous density gradient of Percoll. The complete isolation procedure yielded 17 X 10(6) type II cells per animal (purity = 80%). Either from the crude cell suspensions or the purified preparations, only a small fraction of the type II cell population harbored the inclusions (less than 5%). It is shown that the bounding membranes of the bar-like structures can derive from the endoplasmic reticulum, the nuclear membrane, or the Golgi apparatus. Occasional connections with lamellar bodies were observed, and different levels of complexity in the bar-like structures were also found. The apparent rigid conformation and the orientation of the bar-like structures were taken as evidence for a role of the cytoskeleton in their formation. Because the inclusions do not appear to be new organelles or cellular structures performing a specific function, we propose that their formation may be a transient and limited cellular event in normal cells. However, the stabilization and the generation of the osmiophilic structures, as well as their overproduction, may reflect alterations of the normal physiology of the type II cells.
Exercise-induced alterations in the concentrations of plasma glucagon-like immunoreactivity (GLI), plasma free fatty acids (FFA) and blood glucose and lactate were measured in separate groups of male and female domestic fowl. There were only small changes in blood glucose and lactate concentrations but plasma FFA and GLI rose by up to 450 and 200% respectively. There was evidence that the GLI response was stronger at higher exercise intensities. It is suggested that the mobilization of FFA for use as energy substrates by the working muscles may be stimulated by the enhanced secretion of glucagon.
In this article we report the case of a woman who survived an out-of-hospital cardiac arrest but was left with severe neuropsychological impairments due to anoxia. The deficits included anterograde and retrograde amnesia, dysphasia, disorientation, intellectual deterioration, visual impairments, ataxia, and myoclonus. Despite this degree of impairment the patient retained some insight into her condition which, in turn, created additional emotional problems. Rehabilitation and the problems of long-term care are considered.
The role of combined alpha and beta blockade as a means of limiting infarct size has been studied in a randomised controlled trial using labetalol. Only 166 of 630 (26%) consecutive patients admitted to a cardiac care unit with suspected myocardial infarction were deemed suitable for inclusion; most of the remainder had delayed admission to hospital, were over the age limit of 75, or had complications which precluded the use of labetalol. Those on active treatment received a loading dose followed by a slow intravenous infusion over six hours, and oral therapy for the subsequent five days. Doses were adjusted to maintain systolic pressure in the range 100 to 120 mmHg. The control group received only conventional therapy. Labetalol caused lowering of the blood pressure and heart rate during the phase of intravenous treatment, but little effect occurred subsequently because oral dosage was constrained by low systolic pressures. The group that received active treatment had significantly greater release of CKMB enzyme. Little difference was observed in R wave scores or ejection fraction. Only low doses of labetalol can be used for most patients with acute myocardial infarction. Labetalol cannot be recommended as routine treatment for normotensive patients admitted to hospital with suspected infarction.
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