The ethics of practicing intubation on recently deceased patients.
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Beneficence↗
Biomedical subjects
D A Cook
Publications and source records attributed to D A Cook.
Reduced expression of calponin in canine basilar artery after subarachnoid haemorrhage.
Calponin, an actin- and tropomyosin-binding protein, has been characterized as an inhibitory factor in the smooth-muscle actomyosin activity. The level of calponin was determined in canine basilar arteries in a double-haemorrhage model. Thirty dogs were assigned to three groups: day 0 group, control; day 2 group, dogs sacrificed 2 days after cisternal injection of blood; and day 7 group, dogs given double cisternal injections of blood and sacrificed 7 days after the first injection. Constriction of the basilar artery was confirmed by arterial angiography. Portions of the affected arteries or the corresponding region in control animals were solubilized for sodium dodecylsulphate-polyacrylamide gel electrophoresis and Western blotting. A major band corresponding to calponin was seen at 34 kD in the basilar artery extracts using chicken gizzard polyclonal antibodies. The densitometer values of the band on Coomassie blue-stained gels were expressed as percentages of day 0 control values. The signals of day 2 and day 7 samples were 47% +/- 20% and 23% +/- 12%, respectively (mean +/- standard deviation). The proportions of calponin to actin/tropomyosin in the day 0, day 2, and day 7 groups were 13% +/- 6%, 6% +/- 2%, and 4% +/- 2%, respectively. The reduced expression of calponin may be related to sustained contraction during cerebral vasospasm.
Animals↗
Method for assessing food intakes in terms of servings based on food guidance.
We describe a method for comparing food intakes reported in surveys with recommendations given in the US Department of Agriculture's food guide pyramid. Such comparison was previously difficult because many foods are eaten as mixtures that cannot be categorized into pyramid food groups and because food intake data and food recommendations are expressed in different units of measurement. We developed a recipe file showing ingredients at multiple levels of breakdown and used it to disaggregate food mixtures into their ingredients so that they could be placed into pyramid food groups. Food-specific weight consistent with the pyramid definitions for serving sizes were derived from the food code book of the 1989-1991 Continuing Survey of Food Intakes by Individuals and used to develop a serving-weight file. Data collected from 8181 adults aged > or = 20 y in the survey were used to estimate the mean number of servings from pyramid food groups and percentages of the population meeting pyramid recommendations. The mean numbers of servings were close to the minimum recommendations for the grain, vegetable, and meat groups and well below the minimum recommendations for the fruit and dairy groups. large proportions of adults (43-72%) failed to meet the dietary recommendations. Our method has several nutrition monitoring and nutrition education applications.
Adult↗
Characterizing food intake patterns of American adults.
Food-pattern analysis provides a way to examine diets in a multidimensional context. This study examined the diets of 8181 adults in the 1989-1991 Continuing Survey of Food Intakes by Individuals and evaluated whether they met the federal recommendations for each of five food groups. The sample was partitioned among 32 different food-intake patterns, six of which represented 44% of the population. Nutrient profiles associated with each of the patterns indicated that failure to meet one or more of the food-group recommendations was associated with nutrient inadequacy, macronutrient imbalance, or both. A reexamination of the data to account for low energy reporters did not alter these findings. The pattern of meeting all five of the food-group recommendations was among the least common, accounting for only 1% of adults' intakes.
Adult↗
In vivo angioplasty prevents the development of vasospasm in canine carotid arteries. Pharmacological and morphological analyses.
BACKGROUND AND PURPOSE: To study the effects of in vivo transluminal balloon angioplasty (TBA) on the structure and function of the arterial wall, a canine model of hemorrhagic cerebral vasospasm of the high cervical internal carotid artery (ICA) was used. This model was also used to determine whether TBA performed before clot placement could prevent the development of vasospasm. METHODS: Twelve dogs underwent surgical exposure of both distal-cervical ICAs, followed by baseline angiography. One randomly selected ICA in each dog was then subjected to in vivo TBA and repeated angiography. Both distal ICAs were then surrounded with blood clots held by silicone elastomer sheaths. Seven days later angiography was repeated, and all animals were killed. The ICAs in four animals were perfusion-fixed in situ for morphological analysis by electron microscopy, and the arteries in the remaining eight animals were removed and immediately immersed in oxygenated Krebs' solution. Contractile responses of isolated arterial rings from each ICA were recorded after treatment with KCl, noradrenaline, serotonin, and prostaglandin F2 alpha, while relaxations in response to the calcium ionophore A23187 and papaverine were recorded after tonic contraction to noradrenaline had been established. The morphology and pharmacological responses of ICAs that had been exposed to blood with or without prior TBA were compared with data obtained from control arterial segments of intact, more proximal regions of the ICAs from each animal. RESULTS: TBA resulted in immediate angiographic enlargement of the ICA lumen that was still evident 7 days later despite the placement of clotted blood around the artery. Scanning and transmission electron microscopy demonstrated flattening of the intima and internal elastic lamina in these dilated arteries, associated with patchy losses of endothelial cells. In contrast, ICAs that had been exposed to clotted blood but had not undergone prior TBA developed consistent angiographic and morphological vasospasm. In comparison with control vessels and nondilated vasospastic vessels, vessels dilated with TBA and then exposed to clotted blood showed significantly diminished responses to all compounds tested, with the exception of prostaglandin F2 alpha. CONCLUSIONS: These results indicate that in vivo TBA results in a degree of functional impairment of vascular smooth muscle that persists for at least 7 days. This result is consistent with previous observations of the acute effects of TBA in isolated arteries. Furthermore, these results support the hypothesis that normal smooth muscle function is required for the development of vasospasm. Finally, these results indicate that TBA performed before the onset of vasospasm prevents its development.
Angiography↗
A protocol for the measurement of downtime of medical equipment.
The downtime of medical equipment has become an issue of increasing concern within the National Health Service over recent years. No protocol exists to formalize measurement and recording of downtime. A survey of 129 purchasers and providers of radiotherapy maintenance services at 68 establishments in the UK was undertaken, with replies received from 66. Information was gathered on 16 factors affecting the measurement of downtime of radiotherapy equipment. The results of the survey are presented and analysed. The conclusions drawn demonstrate the practicality of introducing a protocol for the measurement of downtime and availability. A draft protocol has been developed from the results of the survey.
Equipment Failure↗
Fraud, abuse, and beyond. Costly pitfalls for physicians who serve Medicare and Medicaid patients.
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Fraud↗
Effect of ketanserin on 5-hydroxytryptamine-induced constriction in isolated, perfused canine basilar arteries exposed to blood.
The blocking effect of ketanserin, a 5-hydroxytryptamine (5-HT)2 receptor antagonist, was examined on responses to intra-luminal 5-HT or potassium chloride (KCl) in isolated and perfused canine basilar arteries before and after extraluminal whole blood by means of the stainless-steel cannula inserting method. Four hours after the application of blood, the constriction to 5-HT was significantly enhanced, while that to KCl was significantly attenuated. The absolute value in the decrease of perfusion pressure for the 5-HT-induced constriction sensitive to ketanserin was much greater after the blood application than that before the application. It is suggested that the augmentation of cerebrovascular responses to 5-HT in the early stage immediately after subarachnoid haemorrhage (SAH) might be mediated by 5-HT2 receptors at least in part. This early constrictor mechanism may be implicated in the aetiology of the following late stage of cerebral vasospasm after SAH.
Animals↗
Effect of clot removal on cerebrovascular contraction after subarachnoid hemorrhage in the monkey: pharmacological study.
Clot removal at early surgery has been reported to be clinically effective for the prevention of cerebral vasospasm following subarachnoid hemorrhage (SAH) due to rupture of an intracranial aneurysm. We examined the most efficacious timing of mechanical clot removal on pharmacological responses in a monkey SAH model. Cynomolgus monkeys (Macaca fascicularis) were randomized into five groups: sham-operated, clot removal in which the clot was removed 48, 72, or 96 h after SAH, and clot groups. An autologous blood clot was placed around the bilateral major cerebral arteries after craniectomy to mimic the hemorrhage. Seven days after the SAH, proximal and successively distal parts of the middle cerebral arteries were cut into rings for isometric tension measurement. The contractile responses to potassium chloride, 5-hydroxytryptamine, norepinephrine, adenosine triphosphate, prostaglandin F20, and hemoglobin were greater in the proximal parts than in the distal parts in each group. Compared with the sham-operated group, the responses of the clot-removal and clot groups to the drugs were progressively attenuated. The maximum responses to 5-hydroxytryptamine in the proximal parts and to adenosine triphosphate in the distal parts started to decrease, significantly, in the clot-removal group 48 h after SAH, while most of the responses to the other agonists began to decrease in the clot-removal groups later than 72 h after SAH. These results suggest that the attenuation of cerebrovascular contractile responses 7 days after SAH is pharmacologically inevitable, even if the clot is removed as early as 48 h after the SAH. Clot removal may thus be recommended within 48h after SAH to ameliorate the severity of cerebral vasospasm following SAH.
Adenosine Triphosphate↗
Measurement-induced improvement in anxiety: mean shifts with repeated assessment.
Some personality test scores improve on retest. Three studies investigated the role of meaning change in producing this phenomenon. In Study 1 multiple versions of a Manifest Anxiety Scale were administered, with counterbalanced item orders. It was found that measurement-induced improvement (a) occurred within a test as well as between test and retest, (b) was unaffected by participants' anxiety scores, and (c) occurred even when the retest contained different items than the first test. Studies 2 and 3 found that as respondents experience more of a test, they are better able to discern its meaning and to use that meaning to interpret an item. These findings indicate that mean shifts in answers from test to retest also occur within a test along with context-induced shifts in meaning.
Anxiety Disorders↗
Endothelium-dependent relaxation and vasospasm in the single-hemorrhage canine model.
We have investigated the relationship between angiographic vasospasm and the ability of spastic vessels to relax in response to agents which promote release of endothelium derived relaxing factor. Vasospasm was induced in dogs by the 'single hemorrhage' technique. Animals received a single intracisternal injection of blood, blood activated with thromboplastin or collagen, or inert material, and angiograms were obtained day 0 and day 7. Vasospasm was estimated by measuring the ratio of the diameter of the vessel before and after treatment. Rings of cerebral artery obtained from these animals were suspended in a standard organ-bath arrangement, contracted with prostaglandin F2 alpha and then treated with increasing doses of adenosine triphosphate or bradykinin, both of which cause relaxation by an endothelium-dependent process. The arteries from animals with moderate to severe vasospasm showed a response to bradykinin and adenosine-triphosphate which was reduced, absent or converted to a contraction, when compared with normal vessels. Vessels in which vasospasm was mild or absent relaxed as expected to these agents. The reduction in vessel diameter showed a highly significant correlation with the reduction in relaxation to bradykinin or adenosine-triphosphate. These results have demonstrated that impairment of endothelium-dependent vasorelaxation correlates with the existence of vasospasm.
Adenosine Triphosphate↗
New antitrust rules ease restrictions on physician networks.
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Antitrust Laws↗
Mechanisms of cerebral vasospasm in subarachnoid haemorrhage.
Cerebrovascular spasm is a slowly developing constriction of the cerebral arteries, which frequently follows subarachnoid haemorrhage and is associated with considerable morbidity and mortality. The condition has been studied by use of models of subarachnoid haemorrhage in the whole animal and examination of isolated blood vessels or vascular smooth muscle cells in culture. The condition probably arises from the action of haemoglobin released from erythrocytes trapped in the subarachnoid clots, although the mechanism of action of haemoglobin remains uncertain. Systemic pharmacotherapy to avert or reverse vasospasm is still experimental.
Animals↗
Calcitonin gene-related peptide as an endogenous vasodilator: immunoblockade studies in vivo with an anti-calcitonin gene-related peptide monoclonal antibody and its Fab' fragment.
1. Calcitonin gene-related peptide (CGRP) is localized in perivascular sensory neurons and is a potent vasodilator. We investigated the utility of immunoblockade as an in vivo technique for probing the role of CGRP as an endogenous vasodilator. 2. The effects of an anti-CGRP monoclonal antibody (MAb; coded C4.19) and its Fab' fragment on CGRP-induced changes in blood pressure and skin blood flow were studied in pentobarbitone-anaesthetized rats. Antidromic skin vasodilatation in the rat hind paw was measured by laser Doppler fluxmetry. 3. The dose-response relationship for the hypotensive effect of intravenous rat alpha CGRP (r alpha CGRP) was similarly shifted rightward by MAb C4.19 IgG (1 mg/rat; intravenously) and Fab' fragment (2 mg/rat; intravenously). The C-terminal fragment of human alpha CGRP (h alpha CGRP8-37) also blocked the hypotensive effect of r alpha CGRP. 4. MAb C4.19 Fab' fragment (2 mg/rat; intravenously) and h alpha CGRP8-37 (100 nmol/kg; intravenously), but not MAb C4.19 IgG (up to 3 mg/rat; intravenously) or normal mouse Fab' fragment (2 mg/rat; intravenously), blocked the increased skin blood flow response to antidromic stimulation of the saphenous nerve. 5. The mean percentage changes in skin blood flow parameters due to MAb C4.19 Fab' fragment were significantly different from those due to normal mouse Fab' fragment (unpaired t-test; P < 0.05) but not from those due to h alpha CGRP8-37. 6. The results demonstrate the pharmacokinetic advantage of Fab' fragment over IgG for immunoblockade studies in vivo and support the role of CGRP in mediating skin vasodilatation.
Animals↗
Vasoconstrictor mechanism of neuropeptides augmented after endothelial removal in isolated, perfused canine basilar arteries.
In order to investigate the functional role of endothelium and vasoeffector mechanism in cerebrovascular responses to neuropeptides, the stainless steel cannula inserting method was applied to examine the responses to intraluminally-applied bradykinin, substance P and vasopressin in isolated and perfused canine basilar arteries. In control vessels with intact endothelium, each neuropeptide induced a monophasic dilation at lower doses, and a biphasic response, i.e., an initial dilation followed by a secondary constriction, at higher doses. The dilation was significantly reduced and the constriction was significantly enhanced, while the dilation to papaverine was not modified by endothelial removal with intraluminal saponin. The same tendency was observed in the responses after extraluminal treatment with oxyhaemoglobin. The monophasic constrictions to prostaglandin F2 alpha and potassium chloride were significantly potentiated by the endothelial removal. The augmented constrictions to the neuropeptides were significantly diminished by indomethacin (a cyclooxygenase inhibitor), OKY-046 (a thromboxane synthetase inhibitor) and nimodipine (a dihydropyridine calcium antagonist), but not by AA-861 (a lipoxygenase inhibitor). These results suggest that the neuropeptide causes an endothelium-dependent dilation and a constriction of smooth muscles, and that the enhanced constriction might be relevant in part with thromboxane A2, linked with calcium influx into smooth muscle cells in cerebral arteries.
Animals↗
Mechanism of acetylcholine-induced constriction enhanced by endothelial removal in isolated, perfused canine basilar arteries.
We examined the responses to intraluminally applied acetylcholine (ACh) in isolated and perfused canine basilar arteries by the stainless-steel cannula-inserting method. In control vessels with intact endothelium, ACh produced a slight vasodilatation followed by a long-lasting vasoconstriction in the absence of induced tone. Propranolol, a beta-adrenoceptor blocker, had no effect on the response to ACh. After endothelial removal with intraluminal saponin, the constrictor component of the response to ACh was significantly enhanced, and the constrictions to prostaglandin F2 alpha (PGF2 alpha) and potassium chloride (KCl) were significantly potentiated. After exposure to extraluminal oxyhemoglobin, the ACh-induced constriction was significantly augmented, whereas the dilator component of the response to calcium ionophore A23187 was significantly attenuated. The enhanced constriction to ACh after endothelial removal was significantly blocked by OKY-046 (a thromboxane synthetase inhibitor) and nimodipine (a dihydropyridine calcium antagonist), but was slightly though not significantly suppressed by AA-861 (a lipoxygenase inhibitor). The response to PGF2 alpha was not altered by OKY-046 or AA-861. These results suggest that the potentiation of ACh-induced constriction after endothelial removal may be mediated in part by thromboxane A2 (TXA2), linked with extracellular calcium entry in smooth muscle cells (SMC). This mechanism might be involved in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH).
Acetylcholine↗
An outbreak of copycat fire raising.
A dangerous outbreak of fire setting occurred on two wards of a Bristol Psychiatric Hospital, in which six patients set eight fires over a five-week period. One was the Intensive Care Unit, the other an admission ward serving the inner city of Bristol. Five of the six patients had moved between the two wards. The sequence of fires is in part explained by 'copycat' behaviour. The fires were set at a time when the hospital was particularly vulnerable because of major service changes. We emphasize the institutional and situational variables that led to disturbed behaviour in a vulnerable group of individuals, with inadequate controls over tension and anxiety.
Adult↗
Evaluating food fortification options: general principles revisited with folic acid.
OBJECTIVES: This article uses folic acid as an example to illustrate some of the complex issues and general principles that emerge when evaluating fortification of the food supply as one possible means to address a public health recommendation. METHODS: Distributions of current daily folate intakes from conventional foods and dietary supplements were estimated. Intakes that might result from fortification of cereal-grain products and ready-to-eat cereals at various levels for eight age-gender groups were also estimated by using the US Department of Agriculture's 1987-1988 Nationwide Food Consumption Survey. RESULTS: The results illustrate that fortification of the US food supply tends to increase folate intakes of consumers at the high end of the intake distribution curves in the general population to a greater extent than it affects consumers at the low end of the intake distribution curves in the target population. CONCLUSIONS: The effectiveness of food fortification options for a target population and the safety for the general population impose conflicting challenges that must be considered concurrently when making decisions about fortifying the US food supply.
Adolescent↗