The influence of the bolus injection rate of propofol on its cardiovascular effects and peak blood concentrations in sheep

The influence of the bolus injection rate of propofol on its cardiovascular effects has not been extensively studied. We therefore examined the influence of the injection rate of i.v. bolus doses of propofol on its acute cardiovascular effects and peak blood concentrations in seven chronically instrumented sheep. Each received i.v. propofol (200 mg) over 2 min (slow injection) and 0.5 min (rapid injection) on separate occasions in random order. The rapid injection was associated with more profound decreases in mean arterial blood pressure than slow injection (35.7% vs 23.7% maximal reductions from baseline, respectively; P = 0.02). There were no significant differences between the injection rates for peak reductions in myocardial contractility, increases in heart rate, or degree of respiratory depression. Concurrently, the rapid injections were associated with significantly higher arterial (26.9 vs 11.9 mg/L) propofol concentrations in a manner consistent with indicator dilution principles. There were no differences in the peak coronary sinus concentrations between the injection rates. We conclude that the rapid injection of propofol in the context of the induction of anesthesia produced significantly higher peak arterial propofol concentrations and suggest that it is these higher concentrations that produced relatively greater reductions in arterial blood pressure from rapid injections. Implications: Propofol is injected into a vein to initiate anesthesia. It can cause a rapid decrease in blood pressure, which may be dangerous to the patient. We examined the effect of rapid and slow injection rates of propofol in sheep and found that rapid injection caused a greater decrease in blood pressure. This was because rapid injection caused higher concentrations of propofol in the blood immediately after the injection. We believe that if the same processes occur in humans, there may be little advantage in injecting propofol rapidly.     

Solitary necrotic nodules of the liver

An experience is reported with solitary necrotic nodules of the liver, rare benign lesions described for the first time in 1983. Two patients were referred to our department because of the presence of hepatic lesions that radiology showed to be suspected secondary liver tumors. At laparotomy, both patients underwent liver resections because the lesions appeared to be malignant. Subsequent histological examination of the surgical specimens revealed that both were solitary necrotic nodules of the liver. These were the only solitary necrotic nodules found in a total of 840 operations carried out in our department since October 1981. Although they are completely benign, solitary necrotic nodules have a similar ultrasound pattern and radiological features to metastases and have been described in the literature during the follow-up of patients with other tumors. Uncertainty remains as to the etiology of these lesions, which still represent an occasional finding in liver surgery.     

Temporal expression of pro-inflammatory cytokines and inducible nitric oxide synthase in experimental acute Chagasic cardiomyopathy

Pelizaeus-Merzbacher disease (PMD) is a dysmyelinating disease resulting from mutations, deletions, or duplications of the proteolipid protein (PLP) gene. Distinguishing features of PMD include pleiotropy and a range of disease severities among patients. Previously, we demonstrated that, when expressed in transfected fibroblasts, many naturally occurring mutant PLP alleles encode proteins that accumulate in the endoplasmic reticulum and are not transported to the cell surface. In the present communication, we show that oligodendrocytes in an animal model of PMD, the msd mouse, accumulate Plp gene products in the perinuclear region and are unable to transport them to the cell surface. Another important aspect of disease in msd mice is oligodendrocyte cell death, which is increased by two- to threefold. We demonstrate in msd mice that this death occurs by apoptosis and show that at the time oligodendrocytes die, they have differentiated, extended processes that frequently contact axons and are expressing myelin structural proteins. Finally, we define a hypothesis that accounts for pathogenesis in most PMD patients and animal models of this disease and, moreover, can be used to develop potential therapeutic strategies for ameliorating the disease phenotype.     

Rice (Oryza sativa) centromeric regions consist of complex DNA

Rice bacterial artificial chromosome clones containing centromeric DNA were isolated by using a DNA sequence (pSau3A9) that is present in the centromeres of Gramineae species. Seven distinct repetitive DNA elements were isolated from a 75-kilobase rice bacterial artificial chromosome clone. All seven DNA elements are present in every rice centromere as demonstrated by fluorescence in situ hybridization. Six of the elements are middle repetitive, and their copy numbers range from approximately 50 to approximately 300 in the rice genome. Five of these six middle repetitive DNA elements are present in all of the Gramineae species, and the other element is detected only in species within the Bambusoideae subfamily of Gramineae. All six middle repetitive DNA elements are dispersed in the centromeric regions. The seventh element, the RCS2 family, is a tandem repeat of a 168-bp sequence that is represented approximately 6,000 times in the rice genome and is detected only in Oryza species. Fiber-fluorescence in situ hybridization analysis revealed that the RCS2 family is organized into long uninterrupted arrays and resembles previously reported tandem repeats located in the centromeres of human and Arabidopsis thaliana chromosomes. We characterized a large DNA fragment derived from a plant centromere and demonstrated that rice centromeres consist of complex DNA, including both highly and middle repetitive DNA sequences.     

Corneal endothelial cell measurements in megalocornea

A pedigree of megalocornea manifested many of the characteristic features as well as some less common features of the disorder. Endothelial specular microscopy of affected patients disclosed normal endothelial cell densities and morphologic characteristics and increased total endothelial cell populations, suggesting a process of total corneal hyperplasia. In contrast, unpublished data indicate diminished densities in congenital glaucoma, a finding more consistent with corneal distention. We conclude that specular microscopy may be of value in differentiating the two disorders, although larger series are necessary for confirmation.     

Control of food handling by cutaneous receptor input in squirrels

In a complementary neuroanatomical study by Brenowitz in 1980, it was shown that tree squirrels (Sciurus niger) have a higher relative density of mechanoreceptors in their glabrous forepaw skin than do ground squirrels (Spermophilus tridecemlineatus). The main purpose of this sudy was to test the prediction that tree squirrels would depend upon somatic sensory (cutaneous) input from their forepaws to a greater extent than would ground squirrels in food handling behavior. In addition, a series of more general questions about the sensory control of food handling was examined. First, using different sized food items, it was shown that food handling (rate of manipulation) is subject to sensory control, in general. Secondly, comparision of sham-operated groups with groups receiving median nerve (innervating the palmar surface) lesions showed that cutaneous input from the volar surface of the forepaw contributes to the sensory control in both species of squirrels. Thirdly, comparison of lesion effects in the two species showed that, as predicted, tree squirrels depend upon cutaneous input from their volar forepaw to a greater extent than do ground squirrels. Fourthly, by reanalyzing the above data it was shown that there is continued sensory feedback from food items rather than only an initial evaluation of them.     

Quantitative evaluation of somatotrophic cells (SC) in the adenohypophysis of normal and diabetic male Chinese hamsters

Free amino acid determinations in the cerebrospinal fluid of patients with Parkinson's disease or other extrapyramidal disorders showed that in both groups most amino acids were increased. Significantly increased amino acids were neutral and basic amino acids. Amino acid clusters were present and corresponded with the grouping of amino acids in accordance with amino acid transport systems. The amino acids within the clusters showed a remarkable degree of correlation, and there was a notable correlation between the clusters both in the parkinsonian group and in the group of extrapyramidal disorders, but not in a control group. Our data suggest that in a number of extrapyramidal disorders, Parkinson's disease included, a more generalized abnormality exists than neuronal loss only and, in addition, that patients with these neurologic conditions have a common biochemical defect in their amino acid transport systems.     

Multiple choice questions for continuing education in family medicine

Multiple choice questions used in continuing medical education may require characteristics different from those used in tests and examinations. The questions of three continuing education exercise were assessed by 48 board certified family physicians. Each physician answered one third of the questions and then judged them on usefulness in patient management, as discriminators of quality of medical care, and on educational value. The relevance of each question was determined by a composite index based on these factors. The content of each question was independently analyzed by three physicians. Relevant questions tended to be those concerned with surgery, symptoms, and management, and those requiring more than simple factual recall. Questions on office management or concerning specific diagnoses were considered less relevant. Neither the manner of asking the question nor the severity of the illness appeared to influence relevance. This information should benefit those developing continuing education programs for family physicians, especially those designed for self-administered individual learning.     

Fatal anaphylactic reaction to tetracycline in the postoperative period

A case of anaphylactic reaction in the form of acute cyanosis, hypotension with sudden and unexpected death of a patient in the post-operative period following the administration of tetracycline is described. There was no history of previous exposure to the drug.