Effects of postural changes and removal of vestibular inputs on blood flow to and from the hindlimb of conscious felines.

Considerable data show that the vestibular system contributes to blood pressure regulation. Prior studies reported that lesions that eliminate inputs from the inner ears attenuate the vasoconstriction that ordinarily occurs in the hindlimbs of conscious cats during head-up rotations. These data led to the hypothesis that labyrinthine-deficient animals would experience considerable lower body blood pooling during head-up postural alterations. The present study tested this hypothesis by comparing blood flow though the femoral artery and vein of conscious cats during 20-60 degrees head-up tilts from the prone position before and after removal of vestibular inputs. In vestibular-intact animals, venous return from the hindlimb dropped considerably at the onset of head-up tilts and, at 5 s after the initiation of 60 degrees rotations, was 66% lower than when the animals were prone. However, after the animals were maintained in the head-up position for another 15 s, venous return was just 33% lower than before the tilt commenced. At the same time point, arterial inflow to the limb had decreased 32% from baseline, such that the decrease in blood flow out of the limb due to the force of gravity was precisely matched by a reduction in blood reaching the limb. After vestibular lesions, the decline in femoral artery blood flow that ordinarily occurs during head-up tilts was attenuated, such that more blood flowed into the leg. Contrary to expectations, in most animals, venous return was facilitated, such that no more blood accumulated in the hindlimb than when labyrinthine signals were present. These data show that peripheral blood pooling is unlikely to account for the fluctuations in blood pressure that can occur during postural changes of animals lacking inputs from the inner ear. Instead, alterations in total peripheral resistance following vestibular dysfunction could affect the regulation of blood pressure.

Transneuronal tracing of neural pathways that regulate hindlimb muscle blood flow.

Despite considerable interest in the neural mechanisms that regulate muscle blood flow, the descending pathways that control sympathetic outflow to skeletal muscles are not adequately understood. The present study mapped these pathways through the transneuronal transport of two recombinant strains of pseudorabies virus (PRV) injected into the gastrocnemius muscles in the left and right hindlimbs of rats: PRV-152 and PRV-BaBlu. To prevent PRV from being transmitted to the brain stem via motor circuitry, a spinal transection was performed just below the L2 level. Infected neurons were observed bilaterally in all of the areas of the brain that have previously been shown to contribute to regulating sympathetic outflow: the medullary raphe nuclei, rostral ventrolateral medulla (RVLM), rostral ventromedial medulla, A5 adrenergic cell group region, locus coeruleus, nucleus subcoeruleus, and the paraventricular nucleus of the hypothalamus. The RVLM, the brain stem region typically considered to play the largest role in regulating muscle blood flow, contained neurons infected following the shortest postinoculation survival times. Approximately half of the infected RVLM neurons were immunopositive for tyrosine hydroxylase, indicating that they were catecholaminergic. Many (47%) of the RVLM neurons were dually infected by the recombinants of PRV injected into the left and right hindlimb, suggesting that the central nervous system has a limited capacity to independently regulate blood flow to left and right hindlimb muscles.

Vestibular inputs elicit patterned changes in limb blood flow in conscious cats.

Previous experiments have demonstrated that the vestibular system contributes to regulating sympathetic nervous system activity, particularly the discharges of vasoconstrictor fibres. In the present study, we examined the physiological significance of vestibulosympathetic responses by comparing blood flow and vascular resistance in the forelimb and hindlimb during head-up tilt from the prone position before and after the removal of vestibular inputs through a bilateral vestibular neurectomy. Experiments were performed on conscious cats that were trained to remain sedentary on a tilt table during rotations up to 60 deg in amplitude. Blood flow through the femoral and brachial arteries was recorded during whole-body tilt using perivascular probes; blood pressure was recorded using a telemetry system and vascular resistance was calculated from blood pressure and blood flow measurements. In vestibular-intact animals, 60 deg head-up tilt produced approximately 20% decrease in femoral blood flow and approximately 37% increase in femoral vascular resistance relative to baseline levels before tilt; similar effects were also observed for the brachial artery ( approximately 25% decrease in blood flow and approximately 38% increase in resistance). Following the removal of vestibular inputs, brachial blood flow and vascular resistance during head-up tilt were almost unchanged. In contrast, femoral vascular resistance increased only approximately 6% from baseline during 60 deg head-up rotation delivered in the first week after elimination of vestibular signals and approximately 16% in the subsequent 3-week period (as opposed to the approximately 37% increase in resistance that occurred before lesion). These data demonstrate that vestibular inputs associated with postural alterations elicit regionally specific increases in vascular resistance that direct blood flow away from the region of the body where blood pooling may occur. Thus, the data support the hypothesis that vestibular influences on the cardiovascular system serve to protect against the occurrence of orthostatic hypotension.

Effects of postural changes and removal of vestibular inputs on blood flow to the head of conscious felines.

Prior studies have shown that removal of vestibular inputs produces lability in blood pressure during orthostatic challenges (Holmes MJ, Cotter LA, Arendt HE, Cass SP, and Yates BJ. Brain Res 938: 62-72, 2002; Jian BJ, Cotter LA, Emanuel BA, Cass SP, and Yates BJ. J Appl Physiol 86: 1552-1560, 1999). Furthermore, these studies led to the prediction that the blood pressure instability results in susceptibility for orthostatic intolerance. The present experiments tested this hypothesis by recording common carotid blood flow (CCBF) in conscious cats during head-up tilts of 20, 40, and 60 degrees amplitudes, before and after the surgical elimination of labyrinthine inputs through a bilateral vestibular neurectomy. Before vestibular lesions in most animals, CCBF remained stable during head-up rotations. Unexpectedly, in five of six animals, the vestibular neurectomy resulted in a significant increase in baseline CCBF, particularly when the laboratory was illuminated; on average, basal blood flow measured when the animals were in the prone position was 41 +/- 17 (SE) % higher after the first week after the lesions. As a result, even when posturally related lability in CCBF occurred after removal of vestibular inputs, blood supply to the head was not lower than when labyrinthine inputs were present. These data suggest that vestibular influences on cardiovascular regulation are more complex than previously appreciated, because labyrinthine signals appear to participate in setting basal rates of blood flow to the head in addition to triggering dynamic changes in the circulation to compensate for orthostatic challenges.

The nonsense of 'knowledge management'

It examines critically the origins and basis of 'knowledge management', its components and its development as a field of consultancy practice. Problems in the distinction between 'knowledge' and 'information' are explored, as well as Polanyi's concept of 'tacit knowing'.

Circulating norepinephrine and cerebrovascular control in conscious humans.

BACKGROUND: Cerebral vasoconstriction without concurrent changes in systemic arterial blood pressure has been observed in both normal individuals and those with idiopathic orthostatic intolerance following several minutes of postural stress when circulating catecholamines are elevated. Therefore, we tested the hypothesis that alpha-adrenergic activation with and without elevated circulating norepinephrine (NE) directly affects cerebrovascular tone in healthy individuals. METHODS: Mean arterial pressure (MAP; tonometry) and cerebral blood flow velocity (MFV) in the middle cerebral artery (transcranial Doppler) were measured in seven healthy individuals during 15 min periods of saline and of 50 (low NE) and 100 (high NE) ng kg(-1) min(-1) infusions of NE. Following this, phentolamine (PHO) was administered to return MAP back to baseline while high NE infusion continued (high NE+PHO). Finally, NE infusion was stopped allowing the persistent effects of PHO to dominate. RESULTS: Circulating NE caused a dose-dependent increase in MAP (P<0.05). During combined high NE+PHO, blood pressure was initially reduced to baseline levels but then increased a second time (P<0.05) during the final approximately 5 min of this phase. MFV remained constant during both low NE and high NE. In contrast, the secondary increase in BP during the late high NE+PHO phase was associated with elevated MFV. Cerebral vascular resistance (CVR) increased during high NE but was reduced to baseline during both early and late portions of the combined high NE+PHO phase (i.e. despite the late-phase increase in blood pressure). CONCLUSIONS: The increase in CVR during NE infusion was explained by an autoregulatory response to the increased blood pressure and not an alpha-mediated constriction. However, PHO appeared to interfere with the normal autoregulatory response to increasing blood pressure.

Implementing a new health management information system in Uganda.

This paper reports on research investigating the health management information system (HMIS) implementation process in Uganda, utilizing the diffusion of innovation and dynamic equilibrium organizational change models. Neither perspective guided the HMIS development process. Instead, technological issues, rather than wider organizational issues, dominated the planned change. The need to consider the organizational context when changing information systems arises because the process is more complex than some practitioners have realized, when attempting to understand the causes of information management problems and developing HMIS in low-income countries. In particular, information system developers had not acknowledged that they were promoting an informational approach to management when they promoted a change from a centralized reporting system to a HMIS supporting use of information at the level of collection. Strategies to facilitate this approach were not advocated. Organizational theory can contribute to the diffusion of innovation framework. It has yielded an integration of Rogers's diffusion of innovation framework and Leavitt's concept of organizational forces in equilibrium. The diffusion framework describes the process, but the organizational model has given the context and reason for aspects of the process. The diffusion model does not predict what needs to change within the organization when a particular innovation is introduced, or how much. The addition of the organizational model has helped. These frameworks can facilitate the introduction of future information management innovations and allow practitioners to perceive their introduction as a staged process needing to be managed. Implications for practice are identified.

Rejection of an innovation: health information management training materials in east Africa.

A shift towards decentralization in many low-income countries has meant more skills are demanded of primary health care managers, including data and information handling at all levels of the health care system. Ministries of Health are changing their central reporting health information systems to health management information systems with emphasis on managers utilizing information at the point of collection. This paper reports on a research study to investigate the introduction of new information management strategies intended to promote an informational approach to management at the operational health service level in low-income countries. It aims to understand the process taking place when externally developed training materials (PHC MAP), which are intended to strengthen health management information systems, are introduced to potential users in an east African country. A case study has been undertaken and this research has demonstrated that the dynamic equilibrium approach to organizational change is applicable to the introduction of new information management strategies and management approaches in low-income countries. Although PHC MAP developers envisaged a technical innovation needing implementation, potential users saw the situation as one of organizational change. Contributions to theory have been made and many implications for introducing new information systems or the informational approach to management are identified. This theoretical framework could also facilitate the introduction of future information management innovations and would allow practitioners to perceive the introduction of information management innovations as one of organizational change that needs to be managed. Consequently, issues that may facilitate or inhibit adoption could be identified in advance.

An unexpected selectivity of a propranolol-derived molecular imprint for tamoxifen.

During the evaluation of molecular imprinted polymers (MIPs) prepared against the drug tamoxifen a propranolol-derived MIP was used as a positive control. Surprisingly the propranolol-derived MIP showed considerable selectivity towards tamoxifen, and was indeed much more selective than the MIP prepared using tamoxifen as the imprint molecule. The consequences of this unexpected, cross reactivity for the use of MIPs in analytical chemistry is discussed.

The illusion of external agency.

People typically underestimate their capacity to generate satisfaction with future outcomes. When people experience such self-generated satisfaction, they may mistakenly conclude that it was caused by an influential, insightful, and benevolent external agent. In three laboratory experiments, participants who were allowed to generate satisfaction with their outcomes were especially likely to conclude that an external agent had subliminally influenced their choice of partners (Study 1), had insight into their musical preferences (Study 2), and had benevolent intentions when giving them a stuffed animal (Study 3). These results suggest that belief in omniscient, omnipotent, and benevolent external agents, such as God, may derive in part from people's failure to recognize that they have generated their own satisfaction.

A modified HET-CAM assay approach to the assessment of anti-irritant properties of plant extracts.

Hen's egg--chorioallantoic membranes were used to screen for and assess anti-irritant properties among aqueous extracts of plants (HET-CAM tests), in connection with searches for plant-derived substances with topical anti-irritant action. The main question to be answered was whether CAM-assay screening of plant extracts could provide a useful route to identifying promising anti-irritant extracts for follow-up clinical testing. To be useful, the method would have to flag materials with strong anti-irritant properties, and would have to avoid registering false negatives. The tests conducted provided positive indications. We measured the delays in onset of three manifestations of membrane irritation-vascular hemorrhaging, membrane lysis and membrane coagulation-observed with test substances relative to positive controls. Aqueous 15% lactic acid, a commonly used irritant in direct tests on human skin, was employed as the test irritant in this study. The ratio [irritation onset times after test substance pre-treatment]:[onset times without test substance pretreatment] was used to measure the anti-irritant power of test substances. A scoring notation was devised for this which treats the delay parameters as independent effects. Most tested plant extracts showed no significant irritant or anti-irritant effects. Among the apparently anti-irritant plant extracts (approx. 10% of all those tested), most showed their greatest effect against hemorrhaging. Lesser but still readily measurable effects against membrane lysis and coagulation were also observed in nearly all the apparently anti-irritant extracts. Two of the tested extracts proved to be membrane irritants. Some key CAM assay results were compared with results obtained in direct tests on human skin using the same test irritant (15% lactic acid). In these comparative tests on skin, an essentially similar pattern of efficacy was obtained, with the plant extract deemed best in the CAM screenings, outperforming the benchmark anti-irritant hydrocortisone. From these initial results it appears that physiological CAM assays may prove useful in screening natural materials for anti-irritant properties, as alternatives to mechanism-dependent biochemical assays, or expensive direct screening tests on human subjects. Further work remains to extend the CAM screening approach to irritants other than lactic acid, and to assess its quantitative powers of prediction of topical anti-irritancy.

Focalism: a source of durability bias in affective forecasting.

The durability bias, the tendency to overpredict the duration of affective reactions to future events, may be due in part to focalism, whereby people focus too much on the event in question and not enough on the consequences of other future events. If so, asking people to think about other future activities should reduce the durability bias. In Studies 1-3, college football fans were less likely to overpredict how long the outcome of a football game would influence their happiness if they first thought about how much time they would spend on other future activities. Studies 4 and 5 ruled out alternative explanations and found evidence for a distraction interpretation, that people who think about future events moderate their forecasts because they believe that these events will reduce thinking about the focal event. The authors discuss the implications of focalism for other literatures, such as the planning fallacy.

Collisionally activated dissociations of aminocyclitol-aminoglycoside antibiotics and their application in the identification of a new compound in tobramycin samples.

Several aminocyclitol-aminoglycoside antibiotics have been studied by tandem mass spectrometry. Glycosidic bond cleavages were the major reactions in the low energy collisionally activated decomposition (CAD) of the protonated antibiotics. Only the glycoside residing on the C6-O of the 2-deoxystreptamine was observed to undergo significant decomposition at the C2-C3 and O-C1 bonds. The comprehension of the CAD of known aminoglycosides aided in the identification of an unknown impurity in tobramycin. The unknown compound was initially detected by reverse phase high-performance liquid chromatography following dinitrofluorobenzene derivatization of the amino groups. The molecular weight of the dinitrobenzene derivative measured by LC mass spectrometry (MS) led to the detection of two isomeric impurities in tobramycin by LC-MS using an amino column. Their CAD spectra were subsequently acquired by LC-MS/MS. One of the two compounds was determined to be a known compound, 6"-O-carbamyltobramycin with the carbamyl group substituted on the glycoside residing on the C6-O of 2-deoxystreptamine. The fragmentation pattern of the other compound was interpreted as that the unknown was also a carbamyltobramycin. The carbamyl group was, however, substituted on 2-deoxystreptamine. It was speculated that the carbamyl group was substituted at the C1 amino group. This compound, to our knowledge, has not been reported before.

A model of dual attitudes.

When an attitude changes from A1 to A2, what happens to A1? Most theories assume, at least implicitly, that the new attitude replaces the former one. The authors argue that a new attitude can override, but not replace, the old one, resulting in dual attitudes. Dual attitudes are defined as different evaluations of the same attitude object: an automatic, implicit attitude and an explicit attitude. The attitude that people endorse depends on whether they have the cognitive capacity to retrieve the explicit attitude and whether this overrides their implicit attitude. A number of literatures consistent with these hypotheses are reviewed, and the implications of the dual-attitude model for attitude theory and measurement are discussed. For example, by including only explicit measures, previous studies may have exaggerated the ease with which people change their attitudes. Even if an explicit attitude changes, an implicit attitude can remain the same.

Immune neglect: a source of durability bias in affective forecasting.

People are generally unaware of the operation of the system of cognitive mechanisms that ameliorate their experience of negative affect (the psychological immune system), and thus they tend to overestimate the duration of their affective reactions to negative events. This tendency was demonstrated in 6 studies in which participants overestimated the duration of their affective reactions to the dissolution of a romantic relationship, the failure to achieve tenure, an electoral defeat, negative personality feedback, an account of a child's death, and rejection by a prospective employer. Participants failed to distinguish between situations in which their psychological immune systems would and would not be likely to operate and mistakenly predicted overly and equally enduring affective reactions in both instances. The present experiments suggest that people neglect the psychological immune system when making affective forecasts.

A new look at anchoring effects: basic anchoring and its antecedents.

In previous anchoring studies people were asked to consider an anchor as a possible answer to the target question or were given informative anchors. The authors predicted that basic anchoring effects can occur, whereby uninformative numerical anchors influence a judgment even when people are not asked to compare this number to the target value. Five studies supported these hypotheses: Basic anchoring occurs if people pay sufficient attention to the anchor value; knowledgeable people are less susceptible to basic anchoring effects; anchoring appears to operate unintentionally and nonconsciously in that it is difficult to avoid even when people are forewarned. The possible mechanisms of basic anchoring and the relation between these mechanisms and other processes of judgment and correction are discussed.

Global fees for managed care in ambulatory surgery.

Managed care, especially health maintenance organizations (HMOs), has expanded rapidly in the United States, with nearly 52,300,000 enrollees. HMOs seek to provide health services in an efficient setting at the most reasonable price. To facilitate this objective, HMOs are shifting the financial risk from payors to the providers. Historically, ambulatory surgery was viewed as a significant cost savings compared with inpatient surgery, eliminating or reducing costly nursing care, boarding charges, medications, and therapies. As the incidence of ambulatory surgery utilization increased from approximately 20% of all surgery performed in the United States in 1982, to nearly 60% in 1993, consuming larger quantities of scarce health dollars, the emphasis shifted to reducing the charges for ambulatory surgery. Initial efforts to contain costs involved utilization management and discounted fee-for-service reimbursement methodologies. When this proved ineffective, a fixed fee per procedure was employed. Recently, full-risk capitation reimbursement has been applied to transfer financial risk and incentive to the provider to mitigate increasing health care costs. Surplus capacity and the consolidation of many covered lives or enrollees with fewer institutional payors (e.g., Blue Cross Blue Shield or Prudential) has made this transformation possible. The combination of these events has provided the HMOs with great leverage. The payors have more choices of providers than ever before, and they seek a safe ambulatory surgery environment at a low charge. In some areas of the country, facility and professional fees are being bundled to differentiate their product and attract more volume. Subcapitation of anesthesia services is being implemented or discussed in regions with very high HMO market penetration. This paper reviews the concept of bundling of services involving anesthesia in ambulatory surgery. It also seeks to provide a process that will assist anesthesiologists to achieve appropriate capitation reimbursement rates from HMOs.

Effects of introspecting about reasons: inferring attitudes from accessible thoughts.

Previous research has shown that analyzing reasons can change people's attitudes, but the exact mechanisms of this effect have not been entirely clear. It was hypothesized that introspecting about reasons focuses people's attention on thoughts that are accessible in memory and increases the extent to which people view their accessible thoughts as applicable to their current attitudes. In Study 1, college students formed initial impressions of a target person, and then positive or negative thoughts about the target person were made memorable. After a delay, half of the participants analyzed reasons for their attitude and half recalled the target person's behaviors. As predicted, people who analyzed reasons reported attitudes toward the target person that were based more on what they could recall about her. Study 2 showed that this effect occurs regardless of whether people initially form an online impression. Implications for the effects of analyzing reasons and for attitude formation are discussed.

Calorimetric evaluation of hydration of cholestyramine.

We have investigated the mechanism of hydration of cholestyramine, a water-insoluble resin used pharmaceutically. Two types of water of hydration (freezing and non-freezing) and the amounts of heat evolved or absorbed during the hydration of cholestyramine were determined. From differential scanning calorimetry, 0.57 g water was observed to be tightly bound per gram of resin (non-freezing water). The hydration of dry cholestyramine was found to be exothermic. The heats of hydration of cholestyramine with chloride or nitrate counter-anions were found to be -6.05 and -3.46 cal g-1, respectively. Some of the partially hydrated cholestyramine samples showed absorption of heat during hydration. The data generated in the study were utilized to better understand the mechanism of hydration and swelling of cholestyramine.

Knowing what you'll do: effects of analyzing reasons on self-prediction.

Analyzing the reasons why one would or would not act in a certain way was predicted to increase the perceived likelihood of the behavior and to lower the accuracy of the self-predictions. In 3 studies, college students predicted whether they would act in friendly or unfriendly ways toward an acquaintance. Those asked to analyze reasons why they would or would not perform the behaviors, as compared with no-analyze controls, were more likely to say they would perform the behaviors, showing a confirmation bias; made less accurate predictions, because analyzing reasons changed their predictions but not their actual behavior; and were more overconfident, because analyzing reasons lowered accuracy but not confidence. Each of these effects was especially pronounced when people's initial liking for the target person was different from the valence of the behavior they were predicting.