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PubMed1997

Laser reflectance imaging of human organs and comparison with perfusion images.

Based on the principle of backscattering of laser radiation from tissues, a non-invasive PC-AT based reflectance imaging technique is developed. The laser beam from a semiconductor laser operating at 670 nm is guided to the tissue site by an optical fibre. The backscattered radiation is collected by another fibre placed in the same probe, and is detected by a photodiode-amplifier assembly. This probe is moved manually over the organs under observation, and the data after the ADC, interpolation and median filtering are displayed in the form of reflectance image of the organ along with grey scale. By this technique images of the human hands and forearms are obtained, which depend on the variations in their colour, composition and blood flow. A comparison is made with perfusion images, obtained by a Periflux laser Doppler flowmeter. These show that the reflectance images provide greater details of the tissue structure than the perfusion images.

Adult↗

PubMed1990

Can a relationship reflect the risk of calcium oxalate urolithiasis?

Different mathematical expressions have been proposed in the literature with the aim to reflect the risk of calcium oxalate urolithiasis. Such expressions, as well as a number of new relationships proposed by us, have been evaluated in 76 patients and 34 normal subjects. Stone-formers were divided into two groups: patients with normal calcium and oxalate excretion and patients with hypercalciuria and/or hyperoxaluria. The results obtained were comparatively evaluated. Several formulae gave some acceptable results, but none of them were excellent. This can be explained by the fact that these discrimination indexes more or less reflect supersaturation and/or inhibition deficit, but none of them reflect promoting factors such as heterogeneous nucleation and/or aggregation capacity.

Calcium Oxalate↗

PubMed1996

"My most meaningful patient". Reflective learning on a general medicine service.

OBJECTIVE: To determine the usefulness of critical-incident reports in facilitating reflective learning and the types of experiences that learners found meaningful on a general medicine service. DESIGN: Team members wrote about their most meaningful patient of the month and what was learned from the patient. They shared their narratives during teaching rounds at the end of each month. The written reports were collected and subjected to qualitative thematic analysis. SETTING: General medicine teaching service of an academic medical center. PATIENTS/PARTICIPANTS: Medical students, residents, and attending physicians. MEASUREMENTS AND MAIN RESULTS: Ninety-eight reports were collected over 10 months and subjected to thematic analysis. Reports were coded for six major themes, with a mean of 2.09 themes per narrative. The number of reports containing each theme was 47 for biomedical, 46 for communication with patients and families, 38 for psychosocial, 32 for the physician's role, 30 for personal feelings, and 14 for ethics. Communication issues constituted the theme most frequently reported by third-year students; biomedical and psychosocial themes by interns; biomedical by supervising residents; and the physician's role by attending physicians. Reports from men and women contained a similar mean number (men 2.101; women 2.128) and distribution of themes. CONCLUSIONS: The critical-incident technique promoted reflection on the meaning of clinical experiences. Qualitative thematic analysis revealed the diversity of meaningful experiences on a general medicine service and the high frequency of nonbiomedical themes. This study suggests that reflective exercises can provide a window into the experience of students and residents.

Clinical Medicine↗

PubMed1979

Membrane surface properties of sheep erythrocytes, an immunological reagent, after different treatments as reflected by partition in two-polymer aqueous phases.

Sheep erythrocytes (E) which, with or without certain treatments, are currently used as "immunological reagents" to detect cells with specific receptors (by rosette-formation) have been partitioned in two-polymer aqueous-phase systems selected so as to reflect charge-associated or lipid-related membrane surface properties. We have found that the partitioning behavior of E is not affected in these phases by reacting the cells with anti-E antibody (either IgG or IgM), forming EA. The additional binding of complement to the cell-antibody complex, forming EAC, results, however, in a marked decrease in the partition coefficient, K. Apparently both the charge-associated and hydrophobic properties reflected by partitioning remain accessible to the phase polymers when the cells are coated with antibody, but are not with the addition of complement. It is interesting that EA can still rosette with T-lymphocytes (14), a property of E, while the additional coating with complement results in EAC which does not appreciably do so (26). Neuraminidase or trypsin treatments of E, which yield Es having quite different rosetting properties with T-lymphocytes (14), cause increased Ks and unchanged Ks, respectively, in phases reflecting lipid-related surface properties. Either treatment causes reduced Ks of E in charged-phase systems. Neuraminidase treatment also results in a reduced electrophoretic mobility of E, while trypsin treatment is not detectable by cell electrophoresis (25). We are currently studying the possible usefulness of employing cell electrophoresis and cell partitioning in charged-phase systems jointly to obtain information on events occurring at the shear plane versus those occurring deeper in the membrane.

Animals↗

PubMed2002

Large-scale pathology-based cancer data--a reflection of population-based cancer data.

Pathology-based cancer data is a high quality reflection of the patterns of cancer in the population it represents, provided the demographic details of the patients are carefully recorded. Relative frequency data is neither a replacement for population-based data nor a suggested alternative; it simply enhances the quality of population data and in very large data sets reflects the cancer patterns observed in the representative populations. Aware of the standard shortfalls of pathology-based data, the department of pathology, The Aga Khan University Hospital (AKUH) standardized its data, representing 53.4% of the cancer data of Karachi Division (Pakistan) and also reflecting the cancer pattern of other provinces of Pakistan. This data was compared with 4 different population and institutional-based data sets. The findings substantiate the observation that despite the problems of interpretation of data from pathology laboratories, they are an invaluable source of information on cancer patterns in much of the world where incidence data are unavailable . If developing countries, unable to organize National Population- Based Registry should as an alternate develop National Pathology-based Registers a well targeted and monitored, a Cancer Control Program would be possible. A good quality, large-scale pathology data with demographic details of the patient recorded can also be extended to give coverage to the population.

Female↗

PubMed2004

Multiple UV reflectance peaks in the iridescent neck feathers of pigeons.

Recent studies of colorful plumage signals in birds have been aided by the finding that birds can see ultraviolet (UV) light and thus may communicate using colors invisible to humans. Some of the pioneering and more pivotal work on avian color vision was performed with domestic pigeons ( Columba livia), yet surprisingly there have been few detailed reports of the UV-reflecting properties of pigeon feathers. Here, I use UV-VIS fiber-optic spectrometry to document the full-spectrum reflectance characteristics of iridescent purple and green neck plumage in pigeons. Neck feathers that appear purple to the human eye exhibit four reflectance peaks-two in the UV and one in the blue and red regions-and thus exhibit a UV-purple hue. Neck feathers that appear green to the human eye are characterized by five spectral peaks: two in the UV (UVA and UVB), a predominant green peak, and secondary violet and red peaks, conferring a UV-purple-green color. Such elaborate UV coloration suggests that birds may use an even more complex and 'hidden' UV signaling system than previously thought.

Animals↗

PubMed2003

Analysis by partial reflection spectrometry of protonated tetraphenylporphyrin adsorbed at a liquid-liquid interface.

Visible reflection spectra of diprotonated meso-tetraphenylporphyrin adsorbates spontaneously formed at a dodecane-aqueous sulfuric acid interface have been measured using a home-made device comprising a prism-cell and variable-angle optics. The tilt angle of the pyrrole ring plane was estimated to be 47 degrees from the interface normal by use of an experimentally evaluated molecular density (1.20x10(-10) mol cm(-2)) of the diprotonated molecule in a monolayer form at the liquid-liquid interface. Positive and negative bands have been observed in the p-polarized partial internal reflection (p-PIR) spectra, whose band locations correspond to those in p-polarized external reflection (p-ER) spectra. Nevertheless, the bands in the p-PIR exhibited reversed sign to those of p-ER spectra. These suggest that the surface selection rule of the p-PIR spectrometry has a reversal rule of p-ER and p-PIR can also be used for the analysis of molecular orientation.

Journal Article↗

PubMed2006

Near-infrared reflectance spectroscopy as a fast and non-destructive tool to predict foliar organic constituents of several woody species.

Near-infrared reflectance spectroscopy (NIRS) was used to estimate N, neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and cellulose contents in leaves of a heterogeneous group of 17 woody species from the Central Western region of the Iberian Peninsula. The sample set consisted of 182 samples of leaves of deciduous and evergreen species, showing a wide range of concentrations determined by reference methods: 6.60-35.2 g kg-1 (N), 15.5-66.0% (NDF), 10.2-57.3% (ADF), 3.45-27.4% (lignin) and 5.79-31.3% (cellulose). Reflectance spectra, obtained for samples of dried and ground leaves, were recorded as log1/R (R=reflectance) from 1,100 to 2,500 nm. NIRS calibrations were developed using multiple linear (MLR) and partial least-squares (PLSR) regressions, and tested by external validation. Spectral data were transformed to the first and second derivative (1D, 2D). The PLSR method and derivative transformations provided the best statistics and showed lower standard errors of calibration (SEC) and higher coefficients of multiple determination (R2). In the external validation the standard errors of prediction (SEP) were 0.76 g kg-1 (N), 2.11% (NDF), 1.47% (ADF), 0.85% (lignin) and 0.86% (cellulose). The results obtained show that NIRS is very effective for the estimation of these organic constituents in leaf tissue of woody species. This technique can be used in ecological or ecophysiological studies as an alternative to the more time-consuming standard methods.

Cellulose↗

PubMed2005

Mirror, mirror on the wall: viewing a mirror reflection of unilateral hand movements facilitates ipsilateral M1 excitability.

Primary motor cortex (M1) excitability is modulated by both ipsilateral limb movement and passive observation of movement of the contralateral limb. An interaction of these effects within M1 may account for recent research suggesting improved functional recovery of the impaired arm following stroke by viewing a mirror reflection of movements of the unimpaired arm superimposed over the (unseen) impaired arm. This hypothesis was tested in the present study using single-pulse transcranial magnetic stimulation (TMS) in eight neurologically healthy subjects. Excitability of M1 ipsilateral to a phasic, unilateral hand movement was measured while subjects performed paced (1 Hz), unilateral index finger-thumb opposition movements. Motor evoked potentials (MEPs) were obtained from the inactive first dorsal interosseous (FDI) in each of four viewing conditions: Active (viewing the active hand), Central (viewing a mark positioned between hands), Inactive (viewing the inactive hand) and Mirror (viewing a mirror-reflection of the active hand in a mirror oriented in the mid-sagittal plane) and with both hands at rest (Rest). MEPs were significantly enhanced during ipsilateral hand movement compared with the Rest condition (P<0.05). Largest MEPs were obtained in the Mirror condition, and this was significant compared with both the Inactive and Central viewing conditions (P<0.05). There was no difference between the dominant and non-dominant hand. Excitability of M1 ipsilateral to a unilateral hand movement is facilitated by viewing a mirror reflection of the moving hand. This finding provides neurophysiological evidence supporting the application of mirror therapy in stroke rehabilitation.

Adult↗

PubMedDate not supplied

Usefulness of a narrow-band reflectance spectrophotometer in evaluating effects of depigmenting treatment.

As a depigmenting treatment, combined topical applications of all-trans retinoic acid (atRA) aqueous gel and 5% hydroquinone, 7% lactic acid ointment were used for Oriental patients with hyperpigmented skin lesions such as senile lentigines and nevus spilus. A narrow-band reflectance spectrophotometer and a tristimulus colorimeter were used to evaluate objectively the intensity of pigmentation and erythema at each clinical visit. L*, a*, and b* values measured with a tristimulus colorimeter (Chroma Meter CR-300) enabled the evaluation of erythema but not pigmentation. On the other hand, the melanin and hemoglobin values measured with a narrow-band reflectance spectrophotometer (Mexameter MX-16) expressed both erythema and pigmentation well. It was revealed that, in our bleaching protocol, the narrow-band reflectance spectrophotometer was quite useful for estimating accurately the intensity of pigmentation and erythema and determining the best time point for the cessation of atRA treatment.

Administration, Topical↗

PubMed2006

Who can get the beneficial effect from lateral lymph node dissection for Dukes C rectal carcinoma below the peritoneal reflection?

PURPOSE: This study was designed to identify those patients with Dukes C rectal carcinoma below the peritoneal reflection who might benefit from lateral lymph node dissection. METHODS: The study involved 104 consecutive Dukes C patients who received total mesorectal excision with lateral lymph node dissection for rectal carcinoma below the peritoneal reflection between 1990 and 2002. The patients were retrospectively divided into three groups: patients without lateral spread (Group I: n = 52), patients with nodal involvement between the inferior hypogastric nerve and the internal iliac artery (Group II: n = 16), and patients with nodal involvement in the obturator space (Group III: n = 36). The patients also were divided into two groups according to the number of lateral nodes involved: less than four (n = 42) and at least four (lateral nodes involved: n = 10). Nodal involvement was determined histologically. RESULTS: The local recurrence and overall five-year survival rates were 5.8 and 66.9 percent in Group I, 18.8 and 59.8 percent in Group II, and 33.3 and 23.6 percent in Group III, respectively. These outcomes did not differ significantly between Groups I and II, but they were significantly worse in Group III than in Groups I and II, with the survival being significantly better in the patients with less than four histologically positive lateral nodes involved (43.2 percent) than in those with at least four positive lateral nodes involved (0 percent). CONCLUSIONS: Lateral lymph node dissection was effective for Dukes C rectal carcinoma below the peritoneal reflection with positive lateral nodes involved in the space between the autonomic nerve and the internal iliac artery and in patients with less than four positive lateral nodes.

Female↗

PubMed2006

Nonpulsatile and noninvasive transmittance and reflectance tissue-bed oximetry.

A new optical device was developed that measures blood pressure noninvasively, in small human subjects (neonates and premature infants) and small animals (Roeder RAR. Transducer for indirect measurement of blood pressure in small human subjects and animals, Purdue University, BME; 2003.: xi, 50 p.). The ability of this device to measure oxygen saturation enhances its value. The objective of this research was to add the ability to obtain SaO(2) from the same device and to obtain the calibration curve. Another objective was to determine which measurement method (transmittance or reflectance) is preferable. This new oximeter is unlike the conventional pulse oximeter in that it does not require a pulse, making it ideal for measuring oxygen saturation noninvasively in small human subjects with small amplitude pulses or without a pulse. A study was performed in 11 pigs, ranging in weight 20-27 kg. The pig tail was used as the measuring site for %SaO(2) measurements. Arterial blood samples were obtained from the femoral artery and oxygen saturation was measured with a blood-gas analyzer. A small blood-pressure cuff was used to render the optical path bloodless. A comparison of the transmittance and reflectance methods for measuring oxygen saturation was made. %SaO(2) measurements ranged from 4% to 100%. It was found that both the transmittance and reflectance methods can be used to measure %SaO(2) reliably in situations with or without a pulse.

Algorithms↗

PubMed2006

Intensification of the emission signals using the reflection mirrors mounted to the sample holder of a fluorimeter.

Effects of the reflection mirrors mounted to the sample holder of a fluorimeter have been investigated. Analytical expressions are given for the emission intensity measured as a function of the concentration or optical density of the sample, in case one or two reflection mirrors are attached beside the sample holder to intensify the emission signals. The emission intensity calculated as a function of the sample concentration agreed well with the experimental data. By mounting two reflection mirrors, the emission signal was intensified by a factor of near 3.5. However, the degree of intensification depended strongly on the sample concentration and the linearity between the sample concentration and the emission intensity deviated significantly with increasing the sample concentration.

Journal Article↗

PubMed2006

Words and wards: a model of reflective writing and its uses in medical education.

Personal, creative writing as a process for reflection on patient care and socialization into medicine ("reflective writing") has important potential uses in educating medical students and residents. Based on the authors' experiences with a range of writing activities in academic medical settings, this article sets forth a conceptual model for considering the processes and effects of such writing. The first phase (writing) is individual and solitary, consisting of personal reflection and creation. Here, introspection and imagination guide learners from loss of certainty to reclaiming a personal voice; identifying the patient's voice; acknowledging simultaneously valid yet often conflicting perspectives; and recognizing and responding to the range of emotions triggered in patient care. The next phase (small-group reading and discussion) is public and communal, where sharing one's writing results in acknowledging vulnerability, risk-taking, and self-disclosure. Listening to others' writing becomes an exercise in mindfulness and presence, including witnessing suffering and confusion experienced by others. Specific pedagogical goals in three arenas-professional development, patient care and practitioner well-being - are linked to the writing/reading/listening process. The intent of presenting this model is to help frame future intellectual inquiry and investigation into this innovative pedagogical modality.

Affect↗

PubMed1991

Detection of clinically suspected deep vein thrombosis using light reflection rheography.

Venography is the current standard for the diagnosis of deep vein thrombosis (DVT). Noninvasive tests have differing sensitivity and specificity, are technically demanding, and may be subject to variability in interpretation. Light reflection rheography (LRR) is a noninvasive method utilizing light-emitting diodes and a sensor to measure light reflected from the skin surface. The intensity of reflected light establishes a graphic pattern that indirectly quantifies parameters of venous function by measuring changes in the microcirculation. Seventy-two patients who underwent contrast venography at our institution were also evaluated with LRR. Twenty-four patients were found to have DVT as demonstrated by venography. Of these, 23 also had DVT detected by LRR. No evidence of thrombus was seen in 45 patients studied by venography; in this group, 35 had normal venous emptying indicated by LRR. Using LRR, a sensitivity of 96% was achieved in the evaluation of clinically suspected DVT. This sensitivity is comparable with other noninvasive tests. In addition, LRR is easy to operate, portable, inexpensive, and not technically demanding. Further investigation is needed to confirm these data and further define the role of LRR in the evaluation of clinically suspected DVT.

Adult↗

PubMed1991

Use of light reflection rheography for diagnosis of axillary or subclavian venous thrombosis.

Noninvasive diagnosis of axillary and subclavian venous thrombosis or documentation of the post-thrombotic syndrome using modalities currently in use is not definitive. Light reflection rheography, which is a reflection of venous pressure changes in the extremity as recorded from the subdermal capillary plexus, was used to correctly diagnose axillary or subclavian venous thrombosis in 11 patients. A positive study was confirmed by phlebography in each instance. There were no instances of false-positive results. The methodology is simple, involving testing of the venous outflow from the upper extremity in response to exercise, application of venous congesting pressure, and measurement of the rate of venous outflow when the congesting pressure is released. Normal respiratory variations of an open venous system are also assessed by this noninvasive modality. The tracing obtained is easy to interpret and provides objective evidence of proximal venous occlusion. The test is not operator-dependent and the instrumentation is relatively inexpensive. We believe that light reflection rheography may be an exciting development in the noninvasive diagnosis of axillary or subclavian venous compromise and merits further trials.

Arm↗

PubMed1985

A reflectance method for quantification of immunological reactions on surfaces.

A simple optical method for determination of thicknesses of organic layers on solid substrates is described. The method is based on the use of a substrate with a high refractive index, e.g., silicon, and reflection of light at an angle of incidence close to the pseudo-Brewster angle. Under these conditions, a reflectance minimum is obtained for light polarized in the plane of incidence. The presence of an organic layer on the surface will increase the reflectance, which is used to determine the thickness of the layer. The physical basis of the method is described briefly, and the application to immunology is demonstrated.

Antigen-Antibody Reactions↗

PubMed1986

Determination of the membrane permeability coefficient and the reflection coefficient by the two-dimensional laminar flow model for intestinal perfusion experiments.

We performed single perfusion experiments in the small intestine of rats in order to prove that the two-dimensional laminar flow model is suitable to determine the membrane permeability coefficient and the reflection coefficient. We used progesterone as an aqueous-diffusion-limited drug, urea as a membrane transport-limited drug and the tritiated water as an intermediate substance. The membrane permeability coefficient for progesterone was calculated to be 3.6 X 10(-4) cm/s. This value did not change when the thickness of the aqueous diffusion layer was altered by increasing the perfusion rate 10-fold. It was directly demonstrated that the two-dimensional laminar flow model was suitable to analyze the data of intestinal perfusion experiments. Membrane permeability coefficients for urea and tritiated water were determined to be 3.4 X 10(-5) cm/s and 8.9 X 10(-5) cm/s, respectively. In the presence of water absorption with the hypotonic perfusion solution, the reflection coefficient for urea was 0.84. This value is thought to be theoretically reasonable, suggesting the usefullness of the two-dimensional laminar flow model to obtain the reflection coefficient in the intestinal membrane.

Animals↗