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PubMed2006

Remineralization of enamel caries can decrease optical reflectivity.

The remineralization of enamel caries can lead to distinct optical changes within a lesion. We hypothesized that the restoration of mineral volume would result in a measurable decrease in the depth-resolved reflectivity of polarized light from the lesion. To test this hypothesis, we measured optical changes in artificial caries undergoing remineralization as a function of depth, using Polarization-sensitive Optical Coherence Tomography (PS-OCT). Lesions were imaged non-destructively before and after exposure to a remineralization regimen. After imaging, microradiographs of histological thin sections indicated that the significant reflectivity reduction measured by PS-OCT accurately represented the increase in mineral content within a larger repaired surface zone. Mineral volume changes arising from remineralization can be measured on the basis of the optical reflectivity of the lesion.

Calcium Phosphates↗

PubMed2005

Service providers' reflections on the affective domain and its influence on decision-making about treatments for chronic pain.

OBJECTIVES: This study sought to explore why service providers, working within the complex area of chronic pain, do not believe that the affective domain influences their decision-making about treatments. METHODS: These results were extrapolated from a larger multistage study based on a series of iterative postal questionnaires. Stage 1 of the large study identified, via postal survey, what treatment components service providers identified as 'important'. In stage 2, a constructivist framework was used to develop an iterative Delphi questionnaire to explore service providers' rationale for these choices. Stage 3 also employed a Delphi process and asked participants to reflect on their previous comments. Stages 2 and 3 used postal questionnaires and summary reports from preceding rounds for background information. RESULTS: Most service providers clearly felt that 'affect' and 'self-image' had little influence on their decision-making compared to 'coherence' and 'purposiveness'. This report presents the findings of the Stage 3 questionnaire, in which participants were asked to reflect and comment on this low level of endorsement for the influence of affect and self-image. Seven themes emerged from the coded data: professionalism, self-protection, affect and experience, lack of reflective skills, ethos of altruism, lack of understanding, and model of practice. Analysis of these themes indicates a tension between what service providers feel they should do and what they actually do. DISCUSSION: Service providers felt that affect and self-image had little influence on their decision-making. However, there is growing evidence in the literature to suggest that it is not possible, or preferable, to divorce emotion from the clinical encounter. Chronic illnesses are complex systems that do not respond optimally to linear problem-solving. Access to a wide range of information, including the affective domain, is important for effective decision-making.

Affect↗

PubMed1985

Sensitive detection of hybridocytochemical results by means of reflection-contrast microscopy.

A new sensitive method for visualization of nonautoradiographic hybridization results in microscopic preparations is described. The method is based on the reflection of the incident light by diaminobenzidine precipitates deposited at the site of hybridization during an indirect hybridocytochemical procedure. The reflected light is detected by means of reflection-contrast microscopy. The applicability of the procedure is demonstrated with nucleic acid probes modified with 2-acetylaminofluorene groups. These in turn are localized in situ by an indirect immunoperoxidase reaction. Besides its sensitivity, this simple visualization technique possesses the additional advantages, over absorption and fluorescence microscopy, that it provides a total DNA counterstain and a chromosomal banding pattern.

Acetoxyacetylaminofluorene↗

PubMed1989

Detection of diaminobenzidine reactions using scanning laser confocal reflectance microscopy.

We used scanning laser confocal microscopy to visualize sites of peroxidatic activity as detected by the diaminobenzidine (DAB) reaction. Imaging was achieved by employing the reflectance mode of this instrument. Intense reflectance was detected after DAB localization of endogenous granule-associated myeloperoxidase in neutrophils and of the exogenous tracer horseradish peroxidase in mouse oocytes. Detection of DAB reaction products with confocal reflectance microscopy will probably be an important addition to the utility of this cytochemical technique.

3,3'-Diaminobenzidine↗

PubMed2006

NT-proBNP reflects right ventricular structure and function in pulmonary hypertension.

The aim of the current study was to investigate whether alterations in N-terminal pro brain natriuretic peptide (NT-proBNP) reflect changes in right ventricular structure and function in pulmonary hypertension patients during treatment. The study consisted of 30 pulmonary hypertension patients; 15 newly diagnosed and 15 on long-term treatment. NT-proBNP, right heart catheterisation and cardiac magnetic resonance imaging measurements were performed, at baseline and follow-up. There were no significant differences between newly diagnosed patients and those on treatment at baseline or follow-up with respect to NT-proBNP, haemodynamics and right ventricular parameters. Relative changes in NT-proBNP during treatment were correlated to the relative changes in right ventricular end-diastolic volume index (r = 0.59), right ventricular mass index (r = 0.62) and right ventricular ejection fraction (r = -0.81). N-terminal pro brain natriuretic peptide measurements reflect changes in magnetic resonance imaging-measured right ventricular structure and function in pulmonary hypertension patients. An increase in N-terminal pro brain natriuretic peptide over time reflects right ventricular dilatation concomitant to hypertrophy and deterioration of systolic function.

Adult↗

PubMed2002

An innovative approach to developing the reflective skills of medical students.

BACKGROUND: Development of the reflective skills of medical students is an acknowledged objective of medical education. DESCRIPTION: Description of an educational exercise which uses an email-based process for developing the reflective skills of undergraduate medical students. Student quotations illustrate learning outcomes qualitatively. DISCUSSION: The process described is immediate, direct, linked to learning objectives, enables rapid responses to be given to the students individually, and is followed by group sharing of learning. It provides a rigorous and robust feedback loop for students. It is relatively economic for teachers and incidentally benefits curriculum design and evolution. The approach supports development of a reflective approach to learning.

Education, Medical, Undergraduate↗

PubMed2003

Systolic and diastolic properties of univentricular hearts in children: insights from physiologic indices that reflect calcium cycling.

Physiologic indices that reflect intracellular Ca2+ cycling were chosen to evaluate contraction and relaxation properties of the univentricular heart. We hypothesized that these indices would be impaired in univentricular hearts. With advances in surgical palliation, an increasing number of children are surviving with univentricular hearts supporting the systemic circulation. Similar to the adult failing heart, single ventricles may also manifest impaired Ca2+ cycling, which may have important therapeutic implications. In our study, we did not actually measure Ca2+ uptake or transients in the cardiac myocyte. Rather, we used previously validated physiologic indices that are known to reflect Ca2+ cycling. Sixteen children were studied, eight with single ventricles (SV) and eight as matched control subjects. Systolic properties were studied using maximal derivative of ventricular pressure (dP/dtmax), force-frequency relationship, and mechanical restitution. Diastolic properties were assessed using time constant of relaxation (tau) and the relaxation-frequency relationship. The critical HR (HRcrit) was assessed from the force-frequency relationship and relaxation-frequency relationship. DP/dtmax and tau were calculated from micromanometric tracings at increasing HRs, generated by right atrial pacing. In SV patients, dP/dtmax was lower than in the control group at each matched HR, and the force-frequency relationship was shifted downward. Restitution of contractility was slower in patients with SV. Tau was similar in both groups at lower HRs but significantly prolonged in the SV group at faster HRs. In the SV, HRcrit was significantly shifted to the left. These findings indicate impaired systolic and diastolic properties of univentricular heart, especially at increased HRs. Because these physiologic indices reflect Ca2+ cycling, it is speculated that the phenomenon of Ca2+ cycling may be impaired in the myocytes of univentricular hearts.

Age Factors↗

PubMed2004

Reflective and impulsive determinants of social behavior.

This article describes a 2-systems model that explains social behavior as a joint function of reflective and impulsive processes. In particular, it is assumed that social behavior is controlled by 2 interacting systems that follow different operating principles. The reflective system generates behavioral decisions that are based on knowledge about facts and values, whereas the impulsive system elicits behavior through associative links and motivational orientations. The proposed model describes how the 2 systems interact at various stages of processing, and how their outputs may determine behavior in a synergistic or antagonistic fashion. It extends previous models by integrating motivational components that allow more precise predictions of behavior. The implications of this reflective-impulsive model are applied to various phenomena from social psychology and beyond. Extending previous dual-process accounts, this model is not limited to specific domains of mental functioning and attempts to integrate cognitive, motivational, and behavioral mechanisms.

Affect↗

PubMed1989

Tandem scanning reflected-light microscopy of cell-substratum adhesions and stress fibres in Swiss 3T3 cells.

This paper describes two applications of the tandem scanning reflected-light microscope (TSM) for the observation of the structure of individual cells growing in tissue culture. First, the TSM is used as an alternative to interference reflection microscopy (IRM) or total internal reflection aqueous fluorescence microscopy (TIRAF) to observe cell-substratum adhesions in unstained living cells growing on a glass coverslip. Second, the TSM is used to produce improved images of cellular structures in 3T3 cells stained with various protein dyes including Napthol Blue Black (NBB) and Coomassie Brilliant Blue (CBB). More specifically, close contacts and focal contacts are resolved in living 3T3 cells, and features of the nucleus, the cytoskeleton and extracellular matrix are resolved in both NBB- and CBB-stained cells. The focal contacts and associated stress fibres are clearly imaged in NBB-stained cells. The TSM is an improvement over conventional incident light microscopy because of the confocal image excludes information from out-of-focus regions of the cytoplasm, and, unlike the laser-based confocal microscope, the actual colour of the specimen is viewed directly with TSM in almost real-time.

Amido Black↗

PubMed2004

The role of muscarinic receptors and intracellular Ca2+ in the spectral reflectivity changes of squid iridophores.

In this paper we describe changes in spectral reflectivity of the light reflectors (iridophores) of the squid Alloteuthis subulata. The spectral changes that can be seen in living squid, can also be brought about by superfusing whole skin preparations with acetylcholine (ACh) (20 micro mol l(-1)) and muscarine (30 micro mol l(-1)) but not nicotine (up to 50 mmol l(-1)), suggesting that cholinergic muscarinic receptors are involved. Changing the osmolarity of the external solution had no effect on spectral reflectivity. To study the iridophores at the cellular level, iridophores were isolated enzymatically. Lucifer Yellow filled the iridophores uniformly, showing cellular individuality. Isolated iridophore cells were loaded with Fura-2 AM and cytoplasmic Ca(2+) was recorded ratiometrically. Intracellular Ca(2+) (resting concentration at 66.16 nmol l(-1)) increased transiently after addition of ACh (50 micro mol l(-1)), muscarine (25 micro mol l(-1)), but not nicotine (up to 5 mmol l(-1)). Ca(2+) also increased when superfused with potassium chloride (10 mmol l(-1)) and caffeine (2.5 mmol l(-1)). Hypo- and hyperosmotic solutions had no effects on the cytoplasmic Ca(2+). By presenting direct evidence that iridophores are polarised cellular structures containing Ca(2+) stores and that they are activated via cholinergic muscarinic receptors, we demonstrate that Ca(2+) is involved in the reflectivity changes of the iridophores of A. subulata. Specimens were prepared for transmission electron microscopy. It was found that the orientations of the plates with respect to the skin surface are in good agreement with the expected orientations based on the prediction that the iridophores act as multilayer reflectors.

Acetylcholine↗

PubMed2005

Evidence for the use of reflected self-generated seismic waves for spatial orientation in a blind subterranean mammal.

Subterranean mammals like the blind mole-rat (Rodentia: Spalax ehrenbergi) are functionally blind and possess poor auditory sensitivity, limited to low-frequency sounds. Nevertheless, the mole-rat demonstrates extremely efficient ability to orient spatially. A previous field study has revealed that the mole-rat can assess the location, size and density of an underground obstacle, and accordingly excavates the most efficient bypass tunnel to detour around the obstacles. In the present study we used a multidisciplinary approach to examine the possibility that the mole-rat estimates the location and physical properties of underground obstacles using reflected self-generated seismic waves (seismic 'echolocation'). Our field observations revealed that all the monitored mole-rats produced low-frequency seismic waves (250-300 Hz) at intervals of 8+/-5 s (range: 1-13 s) between head drums while digging a bypass to detour an obstacle. Using a computerized simulation model we demonstrated that it is possible for the mole-rat to determine its distance from an obstacle boundary (open ditch or stone) by evaluating the amplitude (intensity) of the seismic wave reflected back to it from the obstacle interface. By evaluating the polarity of the reflected wave the mole-rat could distinguish between air space and solid obstacles. Further, the model showed that the diffracted waves from the obstacle's corners could give the mole-rat precise information on the obstacle size and its relative spatial position. In a behavioural experiment using a special T-maze setup, we tested whether the mole-rat can perceive seismic waves through the somatosensory system and localize the source. The results revealed that the mole-rat is able to detect low frequency seismic waves using only its paws, and in most cases the mole-rats determined accurately the direction of the vibratory source. In a histological examination of the glabrous skin of the mole-rat's paws we identified lamellate corpuscle mechanoreceptors that might be used to detect low frequency seismic waves. The combined findings from these different approaches lead us to suggest that a specialized seismic 'echolocation' system could be used by subterranean mammals to determine the most energy-conserving strategy with which to bypass an obstacle, as well as to estimate their distance from the surface, keeping their tunnels at the optimal depth.

Adaptation, Physiological↗

PubMed2002

Reflections on colourful ommatidia of butterfly eyes.

The eye shine of butterflies from a large number of ommatidia was observed with a modified epi-illumination apparatus equipped with an objective lens of large numerical aperture. A few representative cases are presented: the satyrine Bicyclus anynana, the heliconian Heliconius melpomene, the small white Pieris rapae and the small copper Lycaena phlaeas. The colour of the eye shine is determined mainly by the reflectance spectrum of the tapetal mirror and the transmittance spectrum of the photoreceptor screening pigments, if present near the light-guiding rhabdom. Reflectance spectra measured from individual ommatidia show that tapetum and screening pigments are co-expressed in fixed combinations, thus determining different ommatidial classes. The classes are distributed in an irregular pattern that can be rapidly assessed with the novel epi-illumination apparatus. Many butterfly species appear to have red-reflecting ommatidia, which is interpreted to indicate the presence of red-sensitive photoreceptors.

Animals↗

PubMed1983

Effects of pentobarbital anesthesia on the plasma catecholamines and renin activity as reflected in the hemodynamic changes in dogs.

Correlation between hemodynamic changes and plasma catecholamines or renin activity were studied in dogs anesthetized with pentobarbital, 30 mg/kg, i.v. Pentobarbital increased heart rate in all cases regardless of changes in plasma catecholamines, and the increase was not depressed fully by propranolol. Blood pressure (BP) showed a transient decline just after pentobarbital injection and then elevated gradually to one of three levels 30-60 min after anesthesia. In low (62 +/- 4 mmHg, Mean +/- S.E.) and very high BP (169 +/- 7 mmHg), plasma norepinephrine (NE) showed low (305 +/- 55 leads to 89 +/- 22 pg/ml) and high levels (296 +/- 54 leads to 372 +/- 106 pg/ml), respectively, which probably reflect the neurosympathetic activities. In moderately high BP (112 +/- 4 mmHg), however, the hypertension did not necessarily reflect changes in plasma NE. When the level before anesthesia was 108-164 pg/ml, plasma NE increased, whereas it decreased when the level was 182-374 pg/ml. In either case, the level was fixed within 117-182 (154 +/- 6) pg/ml. Plasma renin activity increased after anesthesia and maintained for at least 2 hr. However, the increase were observed regardless of the BP level, and moderately high BP was not depressed by an angiotensin II antagonist. Participation of angiotensin in these sustained BP cases seems unlikely. Plasma epinephrine reflecting adrenal-medullary activity was decreased markedly in all cases, and the low level lasted for at least 2 hr. Changes in plasma dopamine are related to those in plasma NE, and the origin seems to be the same.

Anesthesia, General↗

PubMed2006

Reflective testing--what do our service users think?

BACKGROUND: Reflective testing incorporates the clinical judgement, knowledge and experience of an individual biochemist to request additional tests appropriate to the clinical scenario. Despite being vigorously debated within the biochemistry profession, little is known about how the clinicians directly involved in patient care feel about it. We have conducted a survey to elicit our service users' opinion of reflective testing. METHODS: Ten clinical scenarios, each involving the possible addition of a specific test, were circulated to 520 hospital doctors and 152 general practitioners. The four response options were to add further tests, phone and discuss the case, add a comment to the original results or do nothing. RESULTS: A total of 216 (32%) responses were received. Overall, the majority were in favour of 'adding on' free triiodothyronine (86%), gamma-glutamyltransferase (78%), lipid profile (59%), thyroid peroxidase antibodies (63%), pituitary hormones (58%), troponin (55%) and serum electrophoresis (68%) in the given scenarios. However, only 30% would like a pregnancy test added and only 45% a prostate-specific antigen added without prior consultation. The response differed according to grade and specialty. CONCLUSIONS: Reflective testing is generally welcomed by our service users, provided the nature and implications of the specific test is considered in addition to the full clinical scenario.

Adolescent↗

PubMed2006

Do the incentive payments in the new NHS contract for primary care reflect likely population health gains?

OBJECTIVE: The new contract for primary care in the UK offers fee-for-service (FFS) payments for a wide range of activities in a quality outcomes framework (QOF), with payments designed to reflect likely workload. This study aims to explore the link between these financial incentives and the likely population health gains. METHODS: The study examines a subset of eight preventive interventions covering 38 of the 81 clinical indicators in the quality framework. The maximum payment for each service was calculated and compared with the likely population health gain in terms of lives saved per 100,000 population based on evidence from McColl et al. (1998). RESULTS: Maximum payments for the eight interventions examined make up 57% of the total maximum payment for all clinical interventions in the (QOF). There appears to be no relationship between pay and health gain across these eight interventions. Two of the eight interventions (warfarin in atrial fibrillation and statins in primary prevention) receive no incentive. CONCLUSIONS: Payments in the new contract do not reflect likely population health gain. There is a danger that clinical activity may be skewed towards high-workload activities that are only marginally effective, to the detriment of more cost-effective activities. If improving population health is the primary goal of the NHS, then FFS incentives should be designed to reflect likely health gain rather than likely workload.

Fee-for-Service Plans↗

PubMed2005

Does carboxy-hemoglobin serve as a stress-induced inflammatory marker reflecting surgical insults?

Endogenous carbon monoxide (CO) production has been recently observed to be an index of the inflammatory response, reflecting various insults in critically ill patients. Major surgery is supposed to modulate the production of CO by transcriptional regulation of heme oxygenase (HO). CO is easy to measure as carboxyhemoglobin (CO-Hb) by spectrophotometry; however, whether CO-Hb can be used as an index reflecting surgical insults is unknown. We investigated changes in CO generation during coronary artery bypass graft by measuring CO-Hb concentrations and the expression of HO in circulating blood as well as the expressions of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta). The expression ratios of heme oxygenase-1 (HO-1), TNF-alpha, and IL-1 beta significantly increased after surgery, and these values correlated significantly with one another. CO-Hb concentrations significantly increased after surgery; however, many of those values during artificial ventilation with high inspired oxygen fraction were within normal limits. Furthermore, changes in CO-Hb concentrations were small when preoperative values were high. On the whole, CO-Hb concentrations significantly but weakly correlated with the expression ratios of the inflammatory mediators. However, they did not correlate in the patients who showed higher preoperative CO-Hb concentrations. These data indicate that CO-Hb concentrations can, in general, reflect the inflammatory response induced by surgical insult; however, CO-Hb measurement may not be a useful form of clinical monitoring because of the limited degree of changes, the variation of baseline values, and the necessity for the management under fixed conditions.

Aged↗

PubMed2000

The influence of the peripheral reflection wave on left ventricular hypertrophy in patients with essential hypertension.

The objective of this study was to clarify the relationship between afterload, which consists mainly of the vascular reflection wave, and left ventricular hypertrophy in patients with untreated essential hypertension using the fingertip photoplethysmogram (PTG) and second derivative wave (SDPTG) methods, the simplest and most convenient tools for pulse wave analysis. The augmentation index (AI) is defined as the ratio of the height of the late systolic peak, augmented by the peripheral reflection wave, to that of the early systolic peak caused mainly by left ventricular ejection in the pulse. Increased AI of the PTG and negative d/a, obtained by multiplying the ratio of the late re-decreasing wave (d wave) to the initial positive wave (a wave) of the SDPTG by -1, have the same meaning as increased ascending aortic AI. The left brachial artery blood pressure was measured in 60 patients. The PTG and SDPTG of the right second finger were recorded by a digital photoplethysmograph. The left ventricular mass index (LVMI) was investigated by ultrasonography. Subjects were assigned to one of two groups: a low AI (AI of PTG<1.6; group 1) or a high AI (AI of PTG> or =1.6; group 2) group. LVMI was significantly higher in group 2 than in group 1. In the study group as a whole, the LVMI was positively correlated with both the AI of PTG (r=0.60, p<0.0001) and negative d/a (r=0.63, p<0.0001). An increase in the LVMI was seen in subjects with an augmented late systolic component in the waveform. It was concluded that an increase in the peripheral reflection wave on the left ventricle is one of the important factors causing cardiac hypertrophy in patients with hypertension.

Adult↗

PubMed2004

The timing of the reflected wave in the ascending aortic pressure predicts restenosis after coronary stent placement.

It has been reported that the reflection waveform in the ascending aortic pressure is associated with systemic arterial stiffness. Stiffening of the aortic walls leads to a decrease in coronary perfusion and an increase in restenosis rate. The purpose of this study was to evaluate whether the reflection waveform in the ascending aortic pressure could be used to predict restenosis after percutaneous coronary stenting. One hundred and three patients who underwent percutaneous coronary stenting were enrolled in this study. We measured the inflection time and augmentation index (AIx) to determine the reflection waveform in the ascending aortic pressure at angioplasty. We then prospectively investigated the effect of inflection time and AIx in relation to the subsequent risk of restenosis after coronary stenting. After adjustments for age, gender, smoking habits, hypertension, type 2 diabetes, hypercholesterolemia, stent size, and heart rate, the odds ratio of restenosis in inflection time was 4.62 (95% confidence interval (CI), 1.39 to 15.4) for the lowest tertile of the inflection time level compared with the highest tertile level. As for AIx, the odds ratio of restenosis was 6.96 (95% CI, 1.93 to 25.1) for the highest tertile of the AIx level compared with the lowest tertile level. Inflection time and AIx are related to restenosis after percutaneous coronary stenting.

Adult↗