Biomedical subjects
Publications and source records attributed to D Ross.
Dextroamphetamine (0.15 mg/kg) intravenously administered to a group of normal postmenopausal women induced a dysphoric reaction with drowsiness, annoyance, sadness and anger. Young normal men, receiving the same dosage, responded with elation of mood and alertness. It is suggested that age and hypoestrogenism may alter the behavioural response to amphetamine.
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Between 1966 and 1979 60 patients underwent resection of organic subaortic stenosis at the National Heart Hospital. There was a male:female ratio of 40:20 and an age range of 4 to 56 years (mean 18 years). 22 patients (36.7%) had a single or multiple additional cardiac abnormalities including left ventricular outflow tract obstruction (12 cases), right ventricular outflow tract obstruction (3 cases), ventricular septal defect (6 cases), patent ductus arteriosus (5 cases), aortic coarctation (1 case), congenital mitral stenosis (1 case) and mitral atresia associated with a single ventricle (1 case). Isolated resection of the organic sub-aortic with myotomy and wedge resection was performed in 47 patients and Cooley technique in 2 patients. Total aortic root replacement with a homograft valve was necessary in 4 patients and the 22 patients additional cardiac abnormalities received concomitant surgery. There was one early death (2.6%) amongst the 38 patients with isolated organic sub-aortic stenosis and no late deaths. There were 3 early deaths (13.7%) amongst the 22 patients with additional cardiac abnormalities and one late sudden death after 14 months. There were 7 non-fatal complications: a myocardial infarction, AV block and pacemaker insertion; three mild aortic regurgitations; one mild mitral regurgitation; an arrhythmia due to Wolf Parkinson White syndrome; and an aortic and mitral valve replacement after 9 years. 43 other patients have been followed for 1 to 14 years and are symptom free. Left bundle branch block is present in two of them. Resection of organic sub-aortic stenosis with myotomy and wedge resection is a safe technique and offers an excellent prognosis for this group of congenitally compromised patients.
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A model is described to account for damped oscillatory activity of two interacting neural populations, pyramidal cells and interneurons. This network in the hippocampus is treated as a lumped system with time delays between elements. The physiological mechanism underlying the oscillatory activity appears to involve neural population interaction and cannot be described in terms of a network composed of but two neurons, a single pyramidal cell and a single interneuron. An unusual aspect of the model is the explicit incorporation of an ongoing background input to raise the mean level of activity of the pyrammidal cell population. This model has evolved from a series of studies previously performed on cats. To test the model experiments were performed on rabbits. The data showing oscillatory activity following fornix stimulation in the rabbit indicate that the model can be applied not only to the cat but also to the rabbit. In additions, for commissural stimulation oscillatory potentials of neural populations and individual pyramidal cells were evoked as predicted by the model.
The influence of long-term administration of diphenylhydantoin (DPH) on glucose tolerance and insulin secretion was studied in a random controlled trial in non-epileptic patients receiving the drug for 2 years following recovery from myocardial infarction. While receiving DPH, insulin response to glucose was less than that in the control group, both in absolute terms and when related to the blood glucose level. Despite this, glucose tolerance did not differ from the control group. One month after cessation of DPH, the plasma insulin response had returned to the levels found in the control group, and glucose tolerance had improved to be significantly better than that found in the control group. Thus, the tendency of DPH to impair the insulin response to glucose has been confirmed in this controlled study. However, this does not result in significantly impaired glucose tolerance; it is suggested that the decreased insulin secretion is accompanied by improved insulin sensitivity.
The postoperative data are described of a boy who had a 'switch' operation for transposition of the great arteries with persistent ductus arteriosus more than a year before. The child is living a normal active life. Electrocardiography, echocardiography, and angiocardiography show persistent abnormality of structure and function of the right ventricle but no evidence of reduced coronary blood flow, coarctation at the suture lines of the great arteries, or aortic regurgitation. Reference is made to an identical case operated upon 2 1/2 years ago.
Thirty-nine consecutive patients, aged 5 to 57 years, were followed for two to 15 years with serial haemodynamic studies after removal of fixed subaortic stenosis, which was never a "membrane". Two late deaths occurred, one sudden and one in congestive failure. Of 37 survivors, 25 were asymptomatic and could be classified as good or excellent if judged by well-being. Seven were symptomatic, two having had reoperation for fixed subaortic stenosis, and four needed long-term pacing. Evaluation, including the effect of isoprenaline, showed important dynamic obstruction in 17, five of whom redeveloped fixed obstruction. Seven had congestive features without outflow gradients, and 14 had neither congestion nor outflow obstruction. Complete assessment therefore confirmed that only 14 (36%) were haemodynamically satisfactory; two of them had permanent pacing, and four had had aortic valve surgery. Fixed subaortic stenosis should be removed early, when diagnosed, and completely before secondary myocardial changes occur. Patients however "well" need regular supervision and early haemodynamic assessment. The aortic valve, whether repaired, replaced, or untouched, remains a site for infective endocarditis for life. The fixed subaortic stenosis removed at operation may not be present in that form at birth, but acquired secondary to other congenital abnormalities which remain in the patient.
The relative weight of the free wall of the cardiac right ventricle was ascertained in 177 instances of the sudden infant death syndrome and 30 control infants who had died either in accidents (ten) or of fulminant illness (20). In contrast to the observations of Naeye et al in this regard, these victims of crib death did not exhibit right ventricular hypertrophy. Other evidence to support Naeye et al's contention that such infants are morphologically demonstrably different from normal is well documented. Hence, the significance of this discrepancy between our findings and theirs is unclear.
We attempted to reproduce the work of Naeye with regard to the thickness of the muscular media in small pulmonary arteries among victims of the sudden infant death syndrome, using Naeye's methods. In two separate studies, using two slightly different groups of patients and different ocular grids, we observed a statistically significant difference between crib deaths and accidental deaths in hyperplasia of the arterial muscular media, the only parameter not dependent on point-counting. As no investigator has been able to achieve exactly the same results as Naeye in all three parameters, we concluded that point-counting is probably not the method of choice for this determination. Our data for hyperplasia (in the second phase of the study) correlated with those for the retention of periadrenal brown fat and hepatic erythropoiesis in the same patients.
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Male hooded rats were observed for 6 days following implantation with slow-release subcutaneous pellets containing LSD, mescaline, or control vehicle solution. In animals housed in isolation cages, continuous hallucinogen administration resulted in a gradual increase in head twitches and catatonic postures which peaked 3--4 days after pellet implantation and then declined. In animals housed in social colonies, there were also delayed increases in behavior following hallucinogen-pellet implantation, but these principally involved social behaviors such as fighting by mescaline-treated animals and social grooming by LSD-treated animals. This finding of gradual and cumulative effects of continuous hallucinogen administration contrasts with the usual finding of a rapid tolerance to hallucinogens following repeated injections.
Trimipramine, a new tricyclic antidepressant, was compared to imipramine in 38 hospitalized depressives. Both groups improved, with no major differences seen between the drugs. Analysis of the power of the statistical analysis shows that it is very unlikely that a true difference was present and not detected. There were fewer adverse reactions to trimipramine.
A series of 102 patients with presumptive acute appendicitis entered a prospective, randomized, clinical trial of intrarectal metronidazole given over a 48-h period commencing before surgery. Adequate levels of circulating metronidazole were achieved. A significant reduction in the incidence of anaerobic wound infection was observed in the treated group (P less than 0.02). The convenience and short duration of the prophylactic regimen allowed early discharge from hospital. No untoward effects were observed.
Three patients with reentrant tachycardia are described who had an accessory pathway with a very long conduction time that was incorporated in the tachycardia circuit. The accessory pathway was able to conduct in one direction only, in retrograde manner in two patients and in anteriograde manner in the remaining patient. Evidence is presented that reveals that in the first two patients the accessory pathway was septally located, had completely bypassed the normal atrioventricular (A-V) conduction system, had properties of decremental conduction, and had an atrial exit close to the coronary sinus and a ventricular exit relatively far from the atrioventricular A-V ring. In the third patient, who manifested wide QRS complex during tachycardia, the ventricular end of the accessory pathway seemed to be located close to the right ventricular apex. The atrial end of the pathway could not be localized exactly.
Despite the availability of endoscopy, radiological examination remains an essential method in the investigation of Crohn's disease. Various authors agree that it has an accuracy of 75% (1, 8, 14, 20). In our experience accuracy is somewhere between 70 and 85%. These figures depend on the fact that in about 16% histology is also unable to make a definite diagnosis. Crohn's disease of the large bowel is of significance since it is often misinterpreted as ulcerative colitis, because in 10% of cases there is no involvement of the terminal ileum. The final diagnosis depends on the summation of the individual features whose individual significance must be considered. Malignant involvement of the peritoneum, which has not been extensively described in the radiological literature, may result in changes in the wall of the colon and lead to an appearance resembling Crohn's disease, with consequent errors in diagnosis.