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PubMed1989

[Clinical assessment of a new glucose reflectance meter (Glucoscot II) for the detection of neonatal hypoglycemias].

Glucoscot II, a new glucose reflectance meter and the corresponding test strip "Glucopat" were evaluated for their accuracy in the detection of neonatal hypoglycemia. In 100 neonatal blood samples of 44 neonates glucose was estimated with the reflectance meter and the results were compared with those from a reference method (Beckman-Glucose-Analyser). Hypoglycemia was defined as blood glucose of less than 2.2 mmol/l (40 mg/dl). The correlation between the values obtained by the test strip and the reference values was high (= 0.95). Test sensitivity was 100%, specificity 99% and the predictive value for hypoglycemia was 94%. The incidence of a blood sugar less than 2.2 mmol/l in our study population was 15%. Thirteen percent of glucose values determined with the reflectance meter deviated from the reference value by more then 20%. If our data can be confirmed by others we conclude that the Glucoscot II/Glucopat-system can be recommended as screening-test for hypoglycemia in neonates.

Blood Glucose↗

PubMed1989

Female identity development and self-reflection in late adolescence.

The primary aim of this study was to assess whether the capacity for self-reflection in late adolescent females is related to their level of identity development. It was hypothesized that females characterized by advanced identity status (either identity achievement or moratorium) would exhibit a greater capacity for self-reflection than those characterized by less advanced identity status (foreclosure or diffusion). Of 85 subjects who met the criteria for this study (female college students in the New York City area), 32 fit purely into one of four identity statuses; among this latter group, a t test revealed a significantly higher degree of self-reflection for the advanced identity status subjects. Implications for the psychology of identity are discussed.

Adolescent↗

PubMed1987

Reflectance photoplethysmography as an adjunct to assessment of gravitational acceleration tolerance: preliminary findings.

We have examined the feasibility of using reflectance photoplethysmography to assess Gz acceleration tolerance. Reflectance plethysmograms recorded using a sensor placed on the region of the superficial temporal artery were analysed along with the mean value and the pulsatile component of the Doppler velocity recorded from the opposite temporal artery. The photoplethysmogram signal and pulsatile and mean Doppler velocities were examined as predictors of impending peripheral light loss (PLL) during the experiments. Photoplethysmography correctly predicted a large percentage of the PLL runs (80.5%) and non-PLL runs (98.3%). Mean Doppler velocity predicted a higher percentage of PLL runs (88.1%), but with an unacceptably low rate of non-PLL runs (77.2%). The pulsatile Doppler velocity yielded only 50.7% correct prediction of PLL runs. The results of this preliminary study indicate that, with an improved design of the sensor and the electronics, it may be possible to use reflectance photoplethysmography in acceleration tolerance experiments as a reliable predictor of impending peripheral light loss.

Acceleration↗

PubMed1987

A new type of substratum adhesion structure in NRK cells revealed by correlated interference reflection and electron microscopy.

The substratum adherent membrane of NRK cells in vitro has been studied using correlated interference reflection and surface replica electron microscopy. Structures visualized by interference reflection microscopy were identified in the subsequently prepared platinum-carbon replicas of the adherent membranes. Substratum adherent membranes were prepared using a hypotonic shock/cell shearing technique (lysis-squirting). Typically 20% of the original ventral membrane surface area and 50% of the original focal adhesion number were retained. Microfilament bundle termini, clathrin-coated sheets and pits, cytotic vesicles having a ridged surface and groups of membrane associated particles were well preserved in the replicas. Two types of isolated adhesion structures were found after lysis-squirting. In addition to typical elongate focal adhesions containing actin and vinculin, we report the existence of adherent membrane patches lacking microfilament bundles and negative for vinculin labelling, but coated with clathrin and identifiable in interference reflection microscopy as less dark than focal adhesions and having dot, U- or sinusoidal shapes.

Actin Cytoskeleton↗

PubMed1986

Relative ultraviolet spectral intensity of direct solar radiation, sky radiation and surface reflections. Relative contribution of natural sources to the outdoor UV irradiation of man.

Relative measurements of UVA and UVB radiation from the sun and the sky, as well as the reflected intensity from various land and water surfaces, have been carried out in the Copenhagen area. The measurements were taken in January and in the period April through July and supplemented by measurements in Greenland during May. Likewise, the angular distribution of direct solar radiation and sky radiation close to the direction of the sun was measured with a 0.5 degree field of view. Absolute UV irradiances were measured with detector-filter combinations. Calculations of the relative contributions of direct solar radiation, sky radiation and reflected radiation to the irradiation of a standing person show, in particular, that if seawater with waves is the surrounding scene, its reflected radiation will account for more than 10% of the received UV dose.

Denmark↗

PubMedDate not supplied

[Effect of muscle storage and stimulation on the intensity of Z-reflection of its equatorial x-ray pattern].

The maintenance of frog sartorius muscle in Ringer solution over a long period of time (24 h or more) increases Z-reflection intensity of equatorial X-ray pattern relative to that from fresh (1-2 h) dissecting muscle at sarcomere length more than 2.3 m. Long stimulation deteriorates the equatorial X-ray pattern from muscle. Then with the course of time Z-reflection intensity increases several times, Z and reflections merge, and rigor equatorial X-ray pattern is registered.

Animals↗

PubMed1987

Estimating fat in feces by near-infrared reflectance spectroscopy.

We describe use of near-infrared reflectance spectroscopy (NIRRS) to estimate the amount of fat in feces, for diagnosis of steatorrhea. After sample homogenization, the spectrum of the fecal homogenate is scanned over the near-infrared region. Assay of 94 samples of feces having a known concentration of fat showed the appropriate wavelengths for the NIRRS procedure to be 1734, 1778, 1818, 2270, and 2310 nm. The reflectance output of 47 fecal samples subsequently measured at these wavelengths was used to compute the reflectance scaling factors (F values) by the instrument's microprocessor. Assay of fat content in a further 124 fecal samples, by both hydrolysis/titration (J Biol Chem 1949;177:347) and the NIRRS procedure at the wavelengths and corresponding F values previously determined, gave results that correlated highly satisfactorily. However, the NIRRS procedure demonstrated much better precision.

Feces↗

PubMedDate not supplied

[Relation between the intensity of low-angle equatorial reflections of x-ray diffraction patterns of frog skeletal muscle and sarcomere length].

Dependence of the intensities of low-angle equatorial reflections from frog live resting sartorius muscle on sarcomere length between 1.95 micron and 3.1 micron were studied in stretch and shortening regimes. It is found that intensities of the (10), (20), (30) and Z-reflections increase at sarcomere length increase from about 2 micron, reach maximum value at sarcomere length between 2.3 micron and 2.7 micron, and then fall at further increase of the sarcomere length. The (11) and (21) intensities decrease at sarcomere length increase. A conclusion is drawn that tetragonal lattice of the thin filaments near Z-line gives essential contribution to Z-reflection together with Z-line. It is proposed that hexagonal lattice of A-band and tetragonal lattice of the thin filaments distort each other at sarcomere length less than 2.3 micron and have the most order at sarcomere length between 2.3 micron and 2.7 micron. At further increase of the sarcomere length the packing of both lattices deteriorates apparently due to other factors than in the case of the short sarcomere length.

Animals↗

PubMed1979

[Optimal measurement technic for the vasoconstrictor effect of corticosteroids. Comparative studies with reflection photometry and flow measurement].

In 20 healthy male test subjects, a non-specific ointment base was applied to the back of the hand over 16 hours. Two days later, the same ointment base with 0.25% triamcinolone acetonide was once more applied to the back of the hand over 16 hours. The light reflection of the skin was measured by reflection photometry and the heat transport coefficient was measured fluvographically under the condition of the tourniquet test. The results show that the vasoconstrictor effect of triamcinolone acetonide is best detected by the reflection photometric measurements. In fluvographic measurement, the heat transport coefficient is most affected in maximal reactive hyperemia when the tourniquet has been removed. Application of the base led to a reduction of the blood flow and the water content of the skin after 16 hours, whereas the water content of the skin was unaffected in the presence of triamcinolone acetonide.

Adrenal Cortex Hormones↗

PubMed1982

Pulse wave reflections from arterial discontinuities.

The true or characteristic velocity of pulse waves along different arterial segments in both animals and man often permits the determination of the elastic state of the vessels in health and disease. In this study, the extent to which the measured, or apparent pulse wave velocity (PWV) suffers from reflection effects is investigated. An in vitro test-rig is used to demonstrate that PWV, measured in an elastic tube model, will oscillate about the value characteristic of the vessel wall, as distance progresses close to a discontinuity-generating reflection. These variations are shown to be markedly reduced if the segment length is longer than lambda/4 for the dominant harmonics in the pulse waves. Harmonic analysis of the pulse waves recorded from the elastic tube and from two human volunteers also show that phase velocities oscillate with increasing amplitude as reflection increases.

Animals↗

PubMed1978

Reliability of the Eyetone instrument and the Reflectance Meter in instant blood glucose determinations.

The blood glucose of 271 diabetic subjects (140 boys and 131 girls), followed in a diabetes clinic, was determined by three methods: 1) Reflectance Meter (Ames), 2) Eyetone (Ames), and 3) AutoAnalyzer (Technicon). The results were statistically analyzed at four blood glucose concentration ranges (less than 100, 100 to 200, 201 to 300 and greater than 300 mg/dl). The Eyetone instrument and the Reflectance Meter were found to be simple and exact methods for instant glucose determination as compared with the standard AutoAnalyzer technique. The Reflectance Meter was inexact in the blood glucose range of 201 to 300 mg/dl. The Eyetone instrument was reliable within the range of 10 to 400 mg/dl and was found to be useful for quick glucose determination in the clinic or home.

Adolescent↗

PubMed1983

Reflectance digital matrix photometry.

We have designed and constructed a digital matrix photometer for quantitative measurement of reflected light of small chromophoric areas or colored spots. The areas are divided conceptually into small subunits in which the reflected light is measured. This is done through stepwise scanning with a photodiode array. The sum of the individual reflectance measurements is related to the total amount of an analyte in the spot. We have found that this technique makes possible accurate and precise quantitation of light-absorbing substances in small areas of different sizes, shapes, and internal irregularity measuring as little as 1 mm across.

Color↗

PubMed1982

Effects of lidocaine on conduction through depolarized canine false tendons and on a model of reflected reentry.

Reflected reentry was produced in canine false tendons, mounted in a three-chamber bath, in which the central fiber segment was partially depolarized with an "ischemic" solution to provide an area of impaired conduction. Lidocaine (3-5 mg/l) added to the central chamber further impaired conduction; consequently, reflections were obtained at lower frequencies and over a wider range of stimulation cycle lengths. Complete block followed drug exposure in some preparations. At moderate stimulation rates, the drug-induced shift of the frequency-dependence of manifest reflected reentries was either arrhythmogenic or antiarrhythmic. The action of lidocaine can be explained on the basis of effects on depressed fast or slow response activity at the boundary regions of the ischemic gap. Under slow response conditions, in false tendons homogeneously exposed to a solution containing 20 mM K+ and 9 mM Ca++, lidocaine delayed propagation or induced complete block. In fibers mounted in a single sucrose gap, the drug increased the current required to reach threshold without significant changes in resting potential, threshold voltage or input resistance. The effect of lidocaine on threshold current was lost in Na+-deficient solutions. Thus, lidocaine impairs conduction through K+-depolarized false tendons, an effect that may be related to the Na+ background current.

Animals↗

PubMed1981

[Reflection coefficients in tumor exposure to high-energy laser radiation].

It was shown that a considerable portion of neodymium laser radiation is reflected by human skin neoplasms and transplantable tumors in mice. Melanomas were found to have lower coefficients of reflection compared with nonpigmented tumors. A reflection capacity of all tumors is increased as the energy per impulse increases.

Animals↗

PubMed1994

Light reflection rheography: a simple method of assessing lower limb venous filling.

Light reflection rheography (LRR) has been developed as a simple, quick and non-invasive test of venous function which reproduces the haemodynamic parameters of venous pressure measurements by recording changes in dermal blood content of the lower limb during exercise. It uses the same principles as photoplethysmography (PPG) but is simpler to use in a clinical context. To assess the comparability of LRR, changes in ambulatory venous pressure measurements were compared to simultaneous recordings of LRR in 40 limbs of 20 individuals with venous stasis during and after a standard exercise. One hundred and twenty paired observations were made with an excellent correlation between venous refill times (VRT) recorded by the two methods (r = 0.85, P < 0.01). There was no significant correlation between exercise induced changes in venous pressure (delta P) and light reflection (delta LR) as measures of venous emptying. LRR also demonstrated differences in VRT and delta LR of the limbs of normal subjects and those with signs of venous stasis (varicose veins) (P < 0.0001). Light reflection rheography is thus a simple accurate test of venous function which may be of value in both the pre- and postoperative assessment of venous function.

Adult↗

PubMed1978

Left ventricular mural force changes as reflections of induced alterations in myocardial pump performance.

Strain gauge measurements of changes in left ventricular mural force seen during the ejection phase of the cardiac cycle were examined for a relation to ventricular emptying efficiency. Left ventricular pressure and mural force were recorded at aortic valve opening and closing, then residual fractions were calculated using (a) a representative radius determined from the LaPlace formula (MF = pi PR2), (b) mural force recordings alone, and (c) intraventricular pressure recordings alone. These fractions were compared to other residual fractions simultaneously obtained by thermodilution. Comparisons were made during changes in blood pressure, heart rate, and cardiac contractility. Findings were: 1. Significant correlation is seen when residual fractions, calculated from mural force alone or representative radii (mural force and left ventricular pressure) are regresed against the residual fraction obtained by thermodilution. 2. No relation is seen when residual fraction, calculated from intraventricular pressure, is similarly regressed against the residual fraction obtained by thermodilution. 3. It follows that mural force changes occurring during ventricular ejection do reflect ventricular dimension changes during this period. Moreover, directly recorded mural force can be used to calculate representative ventricular radii which more accurately reflect ventricular size changes. On the other hand, intraventricular pressure, which does not necessarily determine ventricular size, does not reflect ventricular emptying efficiency.

Animals↗

PubMed1993

Reflected line spread function of the human ocular fundus.

Characterisation of the reflection from the fundus of the eye is important for the development of an improved theoretical description of photoscreening. Measurement has been made of the reflected line spread function of the human fundus in vivo using a slit-lamp microscope with video camera and frame-grabber. Line spread functions representative of red, green, and blue light were obtained from fundus sites just temporal to the macula, 10 degrees temporal to the macula, away from the macula temporal, and 30 degrees temporal to the macula. The results show that the lateral spreading of light is greatest for red light, and support the view that red light penetrates further into the fundus before being reflected than green or blue.

Adult↗

PubMed1993

Reflective monitoring in lonely adolescents.

Deficient social skills may be a primary contributor to chronic loneliness during adolescence. Specifically, adolescents at risk of becoming chronically lonely may have trouble reflecting on the appropriateness of their behavior, and learning from their actions. This inability to monitor and reflect on behavior may promote the development of the social, affective, and behavioral problems characteristic of chronic loneliness. Hence, some instances of chronic loneliness may be understood in terms of a developmental psychopathological model which delineates their cognitive, behavioral, and affective components. Dysfunctional familial or peer group interactions in childhood may contribute to the development of a reflective monitoring deficit.

Adolescent↗