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PubMed1998

The level of the collagen cross-link pyridinoline reflects the improvement of cutaneous lesions in one case of skin alveolar echinococcosis.

Cutaneous parasitic lesions, associated with a dense fibrous reaction, markedly improved under albendazole treatment in one case of supraumbilical skin localization of alveolar echinococcosis. Since collagen cross-linking increases during fibrogenesis and contributes to the stability of fibrotic lesions, we monitored the level of the cross-links pyridinoline and pentosidine in skin lesions from this patient to determine if they would reflect the changes occurring during treatment. We looked at the deposition of cross-linked type I collagen by immunohistochemistry and also measured the serum concentrations of pentosidine and of a fragment of type I collagen (ICTP), which contains a site of pyridinoline formation. Albendazole treatment did not affect either the collagen content of skin lesions or the serum concentrations of ICTP and pentosidine, but it led to a pronounced decrease in pyridinoline level concomitant with the disappearance, observed by immunohistochemistry, of extensively cross-linked fibrotic type I collagen. The follow-up of collagen cross-linking by pyridinoline in skin tissue thus appears to be useful in reflecting the improvement of fibrotic skin diseases during therapy.

Albendazole↗

PubMed2005

Photosynthesis and reflectance indices for rainforest species in ecosystems undergoing progression and retrogression along a soil fertility chronosequence in New Zealand.

Measurements of photosynthesis at saturating irradiance and CO2 partial pressure, Amax, "adjusted" normalised difference vegetation index, RaNDVI, and photochemical reflectance index, RPRI, were made on trees sampled along a soil chronosequence to investigate the relationship between carbon uptake and ecosystem development in relation to nutrient availability. Measurements were made on the three most dominant species at six sites along the sequence in South Westland, New Zealand with soil age ranging from < 6 to 120,000 years resulting from the retreat of the Franz Josef glacier. The decrease in soil phosphorus availability with increasing soil age and high soil nitrogen availability at the two youngest sites, due to the presence of a nitrogen-fixing species, provided marked differences in nutrient availability. Mean Amax was high at the two youngest sites, then decreased markedly with increasing site age. Analysis of the data for individual species within sites revealed separation of groups of species in the response of Amax to Nm and Pm, suggesting complex interactions between the two nutrients. There were strong linear relationships for leaf-level RaNDVI and RPRI with Amax, at high irradiance, showing that measurements of reflectance indices can be used to estimate Amax for foliage with a range in morphology and nutrient concentrations. Notwithstanding the change in species composition from angiosperms to conifers with increasing site age, the presence of nitrogen-fixing species, the variability in foliage morphology from flat leaves to imbricate scales and a wide range in foliar nitrogen and phosphorus concentrations, there were strong positive linear relationships between site average Amax and foliage nitrogen, Nm, and phosphorus, Pm, concentrations on a foliage mass basis. The results provide insights to interpret the regulation of photosynthesis across natural ecosystems with marked gradients in nitrogen and phosphorus availability.

Analysis of Variance↗

PubMed2002

Influence of ground reflectivity and topography on erythemal UV radiation on inclined planes.

Erythemal UV irradiance incident on a horizontal surface is not always the best way of estimating the real dose received by humans or animals. For this purpose knowledge of the irradiance incident on inclined planes is required. This study presents a physically accurate model for the calculation of erythemal UV on inclined planes. The influence of ground reflectivity and topography on erythemal UV on inclined planes is investigated as a function of solar zenith and azimuth angle. It is shown that including directional reflectivity does not substantially change the incident dose on inclined planes, the maximum deviation being 10%. The incident erythemal UV may, however, be much more influenced by the surrounding topography and by the direct/diffuse partitioning of the irradiance (which is a function of altitude). Maximum increases in erythemal UV of +57%, compared with the incident erythemal UV on a horizontal plane, were found when the sensor faced the sun with a mountain slope to the left and right of it and for very high altitudes.

Animals↗

PubMed2005

Does central venous pressure or pulmonary capillary wedge pressure reflect the status of circulating blood volume in patients after extended transthoracic esophagectomy?

PURPOSE: We investigated whether central venous pressure (CVP) or pulmonary capillary wedge pressure (PCWP) can accurately reflect the status of circulating blood volume (CBV) during the perioperative period in adult patients after extended transthoracic esophagectomy. METHODS: In 16 adult patients undergoing esophagectomy, simultaneous measurements of CVP, PCWP, and CBV were made at the following seven points: baseline (before surgery) and at 0, 12, 24, 36, 48, and 60 h after admission to the intensive care unit (ICU). CBV was estimated at the bedside with a pulse-dye densitometry method using indocyanine green. The relationship between CBV and these filling pressures was analyzed by linear regression. RESULTS: A total of 122 paired observations were made. The mean value of CBV decreased by approximately -20% at admission to the ICU and increased by approximately 24% of baseline at 48 h after surgery. The time course of CVP and PCWP was similar to that of CBV: both decreased at admission to the ICU, then gradually increased, and peaked at 48 h after surgery. However, both pressures remained within normal ranges, and the actual changes from baseline were small. There was no significant relationship between CBV and CVP (r = 0.17, P = 0.07), and between CBV and PCWP (r = 0.03, P = 0.78). CONCLUSION: Neither CVP nor PCWP accurately reflected the status of CBV in adult patients after extended transthoracic esophagectomy.

Aged↗

PubMed2004

Survival and recurrence after a sphincter-saving resection and abdominoperineal resection for adenocarcinoma of the rectum at or below the peritoneal reflection: a multivariate analysis.

PURPOSE: The purpose of this study was to determine whether the type of operation [sphincter-saving resection (SSR) or abdominoperineal resection (APR)] for primary adenocarcinoma of the rectum at or below the peritoneal reflection affects survival and recurrence after curative surgery. METHODS: This retrospective study included 184 patients who underwent curative surgery achieved by the following two types of operation between 1989 and 1998: (1) SSR ( n = 116 patients) including a low anterior resection with either double-stapling technique ( n = 86) or transanal coloanal anastomosis ( n = 30); (2) APR ( n = 91). The outcome factors evaluated were survival and tumor recurrence. Both univariate and corrected (multivariate Cox's and logistic regression) analyses were used to evaluate the data. The median follow-up was 47.4 months for patients alive at study conclusion. RESULTS: Disease-free and disease-specific survivals, and the frequency and location of recurrence after surgery did not differ between the two types of operations. Multivariate analyses showed that the type of operation was not a significant independent variable in predicting disease-free survival or in the development of both local and distant recurrences after surgery. In addition, tumor-related factors (stage or histologic grade) were significant predictors of the outcome after surgery. CONCLUSIONS: The type of operation (SSR or APR) did not affect the survival or recurrence after a curative resection for adenocarcinoma of the rectum at or below the peritoneal reflection.

Abdomen↗

PubMed2000

Endogenous levels of C-C chemokines MIP-1alpha, MIP-1beta, and RANTES do not reflect the disease course in HIV-seropositive individuals.

It has been shown that the beta (C-C) chemokines macrophage inflammatory protein-1alpha/beta (MIP-1alpha/beta) and RANTES, which are released by CD8+ T cells, are potent inhibitors of HIV viral replication in vitro. To investigate whether serum concentrations of these chemokines reflect such a protective effect in vivo, we measured these in peripheral blood of 60 HIV seropositive patients, 10 healthy subjects, and 10 disease controls. Values were compared with the CDC disease stages and immunological surrogate markers of disease progression, such as CD4+ count, beta2-microglobulin and 5'-neopterin serum levels. In addition, HIV RNA was measured in sera. All three chemokines were not significantly different between HIV patients and healthy individuals, nor were differences of chemokine levels between the CDC stages significant. Instead, disease controls exhibited significantly more MIP-1alpha and MIP-1beta than normals or HIV patients. Furthermore, within the HIV-seropositive subjects we did not observe any relationship with the surrogate markers of HIV disease, CD4+ count, CD4+/CD8+ ratio, beta2-microglobulin, and 5'-neopterin (all correlations NS). HIV viral load did not correlate with the measured chemokine concentrations (r < 0.1, NS). In conclusion, endogenous levels of MIP-1alpha, MIP-1beta, and RANTES do not reflect the hypothesized protective effect on disease progression in HIV infection. Thus, despite potential beneficial effects of the investigated chemokines, other factors may equally contribute to HIV replication control in vivo.

Adult↗

PubMed2004

Event-related potential correlates selectively reflect cognitive dysfunction in schizophrenics.

UNLABELLED: Schizophrenics show event-related potential (ERP) and particularly P3 abnormalities. To study the more detailed relationships between these ERP alterations and cognitive dysfunction we recorded and analyzed ERPs using a particular experimental approach. In 34 schizophrenics and 25 controls ERPs were obtained by a visual Go/Nogo task requiring response inhibition and were decomposed into temporally independent topographical components using Independent Component Analysis (ICA). ICA disentangled different subcomponents of P3. Subcomponent P3b with a parietal maximum amplitude was significantly reduced in the schizophrenics, probably reflecting their attentional deficits. Subcomponent P3ng with a frontal maximum amplitude and enhanced during Nogo condition appeared as an electrophysiological index of response inhibition. A significantly reduced P3ng enhancement, found in schizophrenics, probably reflects their impaired response control. CONCLUSIONS: ICA can successfully identify ERP subcomponents with distinct scalp topographies representing significant differential indices of normal and abnormal cognitive processing. Involvement of frontal brain areas in disturbed executive control in schizophrenics is supported by our ICA findings.

Adult↗

PubMed2006

Plasma natriuretic peptide levels reflect changes in heart failure symptoms, left ventricular size and function after surgical mitral valve repair.

BACKGROUND AND AIM: N-terminal pro-B-type natriuretic peptide (NT-proBNP) has diagnostic and prognostic value in patients with heart failure. The present prospective study was designed to assess whether changes in NT-proBNP levels after surgical mitral valve repair reflect changes in heart failure symptoms and changes in left atrial size, left ventricular size and left ventricular function. METHODS: The study population consisted of 22 patients (mean age: 62.8 +/- 14.2 years, 68% male) undergoing surgical mitral valve repair. Serial NT-proBNP measurements, transthoracic echocardiography and New York Heart Association (NYHA) class assessment were performed before and 6 months after surgery. RESULTS: All patients underwent successful mitral valve repair and no patients died during follow-up. The decrease in NT-proBNP level was associated with the reduction in left atrial dimension (r = 0.72, P < 0.001), left ventricular end-systolic dimension (r = 0.63, P = 0.002), left ventricular end-diastolic dimension (r = 0.46, P = 0.031), and the increase in fractional shortening (r = - 0.63, P = 0.002). Finally, patients with decreasing NT-proBNP levels revealed a significant improvement in heart failure symptoms (NYHA class). CONCLUSION: Changes in NT-proBNP after surgical mitral valve repair reflect changes in heart failure symptoms and changes in left atrial and ventricular dimensions and function.

Aged↗

PubMed2006

Evaluating ecological condition using soil biogeochemical parameters and near infrared reflectance spectra.

Rapid, repeatable assessment of ecological condition is critical for quantitative ecosystem monitoring. Soils provide a sensitive, integrative indicator for which sampling and analysis techniques are well defined. We evaluated soil properties as indicators of ecological condition (subjectively classified into minimally/moderately/severely degraded based on vegetative, hydrologic and edaphic cues) at 526 sites within Ft. Benning military installation (Georgia, USA). For each sample, we measured 17 biogeochemical parameters, and collected high-resolution diffuse reflectance spectra using visible/near infrared reflectance spectroscopy (VNIRS). VNIR spectra have been related to numerous soil attributes - we examine them here for diagnosing integrated response (i.e., ecological condition). We used ordinal logistic regression (OLR) and classification trees (CT) to discriminate between condition categories using both sets of predictors (biogeochemistry and spectra). Sixteen biogeochemical parameters were significantly different across condition categories; however, multivariate models greatly improved discrimination ([calibration, validation] accuracy of [69%, 66%] and [96%, 73%] for OLT and CT models, respectively). Important predictors included total C, total P, and Mehlich K/Ca/Mg. VNIR spectra further improved discrimination ([calibration, validation] accuracy of [74%, 70%] and [96%, 75%] for OLR and CT models, respectively). While spectra were comparably effective at discriminating minimally degraded sites, they were significantly more effective at discriminating severely degraded sites. Error rates across confounding factors suggest that watershed of origin and landscape position were the only important confounders, likely due to imbalanced sampling. We conclude that multivariate diagnosis improves accuracy, and that VNIR spectroscopy, which yields substantial cost and logistical improvements over conventional analyses, provides an effective tool for rapid condition diagnosis.

Ecosystem↗

PubMed2006

Does seston size structure reflect fish-mediated effects on water quality in a degraded semiarid wetland?

This study evaluates whether the size structure of seston (the sum of living and nonliving particles in the water column) reflects the effects of fish on wetland water quality. Using enclosures, we measured water quality and zooplankton community structure in the presence and absence of two fish species with distinct foraging strategies [benthivorous carp (Cyprinus carpio) and planktivorous mosquitofish (Gambusia holbrooki)]. Seston collected from the enclosures was counted and sized automatically with a Coulter counter, and the size structure in the range of 1-60 microm was modelled using the underlying Pareto distribution of particles. Only Cyprinus contributed to a loss of water quality (increased nutrient levels, algal and non-algal turbidity, hypoxia), while both fish species changed zooplankton community composition compared to fishless controls. However, these changes were not reflected in parameters [goodness of fit (r (2)) and parameter c (slopes)] of Pareto models. Multivariate statistics suggest that seston size structure responded more to environmental gradients related to water depth but the relationships were also weak. Our overall result contrasts with the regulation of size spectra constructed from living organisms. Although seston integrates many structural and functional features of the water column, the lack of strong relationships between Pareto model parameters and water quality suggests that a size-based approach to characterise seston structure has a limited potential for assessing biota-mediated effects in wetlands in a straightforward manner.

Animals↗

PubMed2004

Intensity of X-ray reflections from skeletal muscle thin filaments partially occupied with myosin heads: effect of cooperative binding.

For quantitative analysis of contractile proteins of muscle by means of X-ray diffraction, it is important to know how the intensities of individual reflections are related to the number of diffracting objects, i.e., the amount of constituent contractile protein in the muscle cell. Here we diffused various amounts of exogenous myosin subfragment-1 (S1) into overstretched skinned skeletal muscle fibers, either in the presence or absence of Ca2+ , and derived the relationship between the S1 content and the intensities of reflections arising from the S1. In theory, the intensities should be proportional to the square of the S1 content (square law). However, the intensity-content relation deviated systematically from the square law as the S1 content was lowered, and it was better described as a linear function at the lower end of the S1 contents (<20% of saturation level). Model calculations show that the way of deviation is explained by the cooperative manner of S1 binding to the regulated thin filament.

Actins↗

PubMed1991

Does the brachial artery Doppler flow velocity waveform reflect changes in downstream impedance?

Brachial artery Doppler flow velocity waveforms were recorded from 10 nonpregnant women and 19 women with uncomplicated pregnancies. The pregnant group showed higher peak systolic frequencies (3.24 compared with 2.26, p = 0.01), higher maximum end-diastolic frequencies (0.62 compared with 0.25, p = 0.01), and lower pulsatility indices (2.57 compared with 3.95, p = 0.06) when compared with the nonpregnant group. These Doppler changes could reflect the increase in maternal cardiac output and decline in systemic vascular resistance that occur in normal pregnancy. The effect on brachial artery Doppler of acutely increasing downstream impedance by hand immersion in ice-cold water was studied in nine women with uncomplicated pregnancies at 32 to 38 weeks' gestation. Immersion for 15 seconds was associated with a significant reduction in peak systolic frequencies (from 3.06 to 1.97, p less than or equal to 0.005) and maximum end-diastolic frequencies (from 0.82 to 0.03, p less than or equal to 0.005) and a significant increase in the pulsatility index (from 1.87 to 5.62, p less than or equal to 0.005). These changes persisted for the duration of immersion (60 seconds). After immersion, the brachial artery flow velocity waveform returned to its preimmersion pattern by 60 seconds. We conclude that in normal pregnancy, the maternal brachial artery Doppler flow velocity waveform reflects acute and chronic changes in downstream impedance.

Blood Flow Velocity↗

PubMed1974

Discomfort glare and disturbances from light reflections in an office landscape with CRT display terminals.

In the present investigation, the lighting was studied in an office landscape equipped with 17 CRT display terminals. Complaints from the personnel were analysed and compared with the results obtained. Discomfort glare and reflections on the screen were found to be the main causes of the complaints. Discomfort glare resulted from the difference in luminance between the dark screen and other light surfaces in the room. Reflections from windows and ceiling lighting developed on the glossy screen and were often found to have higher luminance values than the text on the screen. On the basis of the present results, guiding principles are suggested for the design of lighting in similar working places.

Journal Article↗

PubMed1981

Hemoperfusion, rate of oxygen consumption and redox levels of mitochondrial cytochrome c (+c1) in liver in situ of anesthetized rat measured by reflectance spectrophotometry.

Utilizing reflectance spectrophotometry, hemoperfusion, rate of oxygen consumption and redox level of mitochondrial cytochrome c (+c1) in livers in situ of anesthetized rats were measured. The transition to the anoxic state was induced by raising the pressure on the liver surface to more than the hepatic blood pressure by pressing with the tip of the optical guide of the reflectance spectrophotometer. During this transition, the average oxygen saturation of hemoglobin in the liver in situ decreased linearly with time until it became 10--20% of the total. This was followed by reduction of mitochondrial cytochrome c (+c1), which reached completion in 10--20 s. The measured O2 consumption rate remained constant until the percentage of oxyhemoglobin in situ decreased to a critical level. There was then a decrease in the rate of O2 consumption which was accompanied by a progressive reduction of cytochrome c (+c1). It was shown that amounts of hemoglobin and mitochondrial respiratory chain cytochromes in the liver in situ could be measured non-invasively and could provide important signals for vital cellular functions. The changes in hemoperfusion and rate of O2 consumption of the liver in situ following ethanol ingestion were also shown in rats, and are briefly discussed with respect to possible application of this method to study the pathophysiology of tissues.

Animals↗

PubMed1980

Correlation between phagocytic and membrane surface properties reflected by partitioning of human peripheral blood monocytes in two-polymer aqueous phases.

Human peripheral blood monocyte-enriched fractions (identified by staining for peroxidase and by sizing) were obtained by velocity sedimentation at unit gravity of peripheral blood mononuclear cells. They were then fractionated by countercurrent distribution (a multiple-extraction procedure) in a charged Dextran/poly(ethylene glycol) aqueous phase system. The monocytes remained viable after the separation (order of 90%). Cells obtained from different cavities along the extraction train were tested for their ability to phagocytize latex particles. With increasing partition coefficient (presumably higher charge-associated membrane properties) the ratio of monocytes that phagocytized to monocytes that did not phagocytize increased appreciably. When, however, monocytes were permitted to phagocytize particles prior to countercurrent distribution, an increase in partition coefficient was associated with an appreciable decrease in the above-specified ratio. Control experiments indicate that the observed change in partitioning behavior cannot be ascribed to an alteration in size and/or density of the monocytes as a function of phagocytosis. It may be due to the internalization of charged surface groups during phagocytosis. We conclude that there is a correlation between the surface properties of monocytes (as reflected by partitiartitioning behavior cannot be ascribed to an alteration in size and/or density of the monocytes as a function of phagocytosis. It may be due to the internalization of charged surface groups during phagocytosis. We conclude that there is a correlation between the surface properties of monocytes (as reflected by partitioning) and their ability to ingest particles. Furthermore, an alteration in the surface charge-associated properties of monocytes as a consequence of phagocytosis is indicated by the cells' reduced partition coefficient.

Cell Membrane↗

PubMed1989

Determination of solute reflection coefficients in kidney brush-border membrane vesicles by light scattering: influence of the refractive index.

Solute reflection coefficients sigma of cell membrane vesicles or liposomes are commonly determined by comparison of the water flow induced by a gradient of the studied solute and that of a reference molecule using light scattering techniques. However, variations in scattered light which are mainly related to change in vesicle volume are also influenced by the refractive index of the surrounding medium. Therefore comparing kinetics of vesicle shrinkage induced by hyperosmotic solutions which have different refractive indexes might lead to an under or over estimation of sigma. We determined sigma NaCl in rat kidney brush-border membrane vesicles by two different approaches using mannitol, a poorly permeant molecule, as reference. (1) The refractive index of the hyperosmotic NaCl solution was adjusted to that of mannitol by addition of polyvinyl pyrrolidone (Mr 40,000), without a significant increase in osmolality. Thereby the change in scattered light intensity induced by osmotic vesicle shrinkage due to gradients of NaCl and mannitol were comparable and led to a sigma NaCl value close to one instead of the previously published value of 0.53. (2) The reflection coefficient was calculated from the lifetime of vesicle shrinkage which is not refractive index-dependent. Again sigma NaCl was not different from one. These results suggest that the water proteic pathways found in the luminal membrane of proximal tubules are not shared by salts.

Animals↗

PubMed1989

Water permeabilities and salt reflection coefficients of luminal, basolateral and intracellular membrane vesicles isolated from rabbit kidney proximal tubule.

The mechanisms of water transport across the rabbit renal proximal convoluted tubule were approached by measuring osmotic permeabilities and solute reflection coefficients of the brush-border and the basolateral membranes. Plasma and intracellular membrane vesicles were isolated from rabbit renal cortex by centrifugation on a Percoll gradient. Three major turbidity bands were obtained: a fraction of purified basolateral membranes (BLMV), the two others being brush-border (BBMV) and endoplasmic reticulum (ERMV) membrane vesicles. The osmotic permeability (Pf) of the three types of vesicle was measured using stop-flow techniques and their geometry was determined by quasi-elastic light scattering. Pf was equal to 123 +/- 8 microns/s (n = 10) for BBMV, 166 +/- 10 microns/s (n = 10) for BLMV and 156 +/- 9 microns/s (n = 4) for ERMV (T = 26 degrees C). A transcellular water permeability, per unit of apical surface area, of 71 microns/s was calculated considering that the luminal and the basolateral membranes act as two conductances in series. This value is in close agreement, after appropriate normalizations, with previously reported transepithelial water permeabilities obtained using in vitro microperfusion techniques thus supporting the hypothesis of a predominantly transcellular route for water flow across rabbit proximal convoluted tubule. The addition of 0.4 mM HgCl2, a sulfhydryl reagent, decreased Pf about 60% in three types of membrane providing evidence for the existence of proteic pathways. NaCl and KCl reflection coefficients were measured and found to be close to one for plasma and intracellular membranes suggesting that the water channels are not shared by salts.

Animals↗

PubMed1995

Energy-dispersive X-ray reflectivity study of the model membranes at the air/water interface.

The results of the first energy-dispersive reflectivity measurements with a (membrane coated) liquid surface are reported. They rely on the calibration curve measured with pure water and can be done without any sample or detector movement with a low-intensity, laboratory-based X-ray generator within less than 1 h. As an illustration, the structural parameters of a diarachidoylphosphatidylcholine monolayer at the air/water interface are determined. It is argued that the energy-dispersive detection in combination with the intense synchrotron radiation can be used for the time-resolved reflectivity measurements on the time-scale of minutes.

Air↗