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In vivo fate of nanomaterials is influenced by the particle size among other parameters. Thus, Health Agencies have identified the size of nanomaterial as an essential physicochemical property to characterize. This parameter can be explored by dynamic light scattering (DLS) that is described in the ISO standard 22412:2008(E) and is one of the methods recognized by Health Agencies. However, no protocol of DLS size measurement has been validated over a large range of size so far. In this work, we propose an extension of validation of a protocol of size measurement by DLS previously validated with certified reference materials (CRM) at 60 and 203nm. The present work reports robustness, precision and trueness of this protocol that were investigated using CRM at 100 and 400nm. The protocol was robust, accurate and consistent with the ISO standard over the whole range of size that were considered. Expanded uncertainties were 4.4 and 3.6% for CRM at 100 and 400nm respectively indicating the reliability of the protocol. The range of application of the protocol previously applied to the size measurement of liposomes and polymer nanoparticles was extended to inorganic nanomaterial including silica nanoparticles.

Acetylene (C 2 H 2 ) and ethane (C 2 H 6 ) are by-products of complex photochemistry in the stratosphere of Saturn. Both hydrocarbons are important to the thermal balance of Saturn’s stratosphere and serve as tracers of vertical motion in the lower stratosphere. Earlier studies of Saturn’s hydrocarbons using Cassini-CIRS observations have provided only a snapshot of their behaviour. Following the vernal equinox in August 2009, Saturn’s northern and southern hemispheres have entered spring and autumn, respectively, however the response of Saturn’s hydrocarbons to this seasonal shift remains to be determined. In this paper, we investigate how the thermal structure and concentrations of acetylene and ethane have evolved with the changing season on Saturn. We retrieve the vertical temperature profiles and acetylene and ethane volume mixing ratios from Δ ν = 15.5 cm - 1 Cassini-CIRS observations. In comparing 2005 (solar longitude, L s ∼ 308°), 2009 ( L s ∼ 3°) and 2010 ( L s ∼ 15°) results, we observe the disappearance of Saturn’s warm southern polar hood with cooling of up to 17.1 K ± 0.8 K at 1.1 mbar at high-southern latitudes. Comparison of the derived temperature trend in this region with a radiative climate model (Section 4 of Fletcher et al., 2010 and Greathouse et al. (2013, in preparation)) indicates that this cooling is radiative although dynamical changes in this region cannot be ruled out. We observe a 21 ± 12% enrichment of acetylene and a 29 ± 11% enrichment of ethane at 25°N from 2005 to 2009, suggesting downwelling at this latitude. At 15°S, both acetylene and ethane exhibit a decrease in concentration of 6 ± 11% and 17 ± 9% from 2005 to 2010, respectively, which suggests upwelling at this latitude (though a statistically significant change is only exhibited by ethane). These implied vertical motions at 15°S and 25°N are consistent with a recently-developed global circulation model of Saturn’s tropopause and stratosphere( Friedson and Moses, 2012 ), which predicts this pattern of upwelling and downwelling as a result of a seasonally-reversing Hadley circulation. Ethane exhibits a general enrichment at mid-northern latitudes from 2005 to 2009. As the northern hemisphere approaches summer solstice in 2017, this feature might indicate an onset of a meridional enrichment of ethane, as has been observed in the southern hemisphere during/after southern summer solstice.

Mid-infrared spectral observations Uranus acquired with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope are used to determine the abundances of C 2 H 2 , C 2 H 6 , CH 3 C 2 H, C 4 H 2 , CO 2 , and tentatively CH 3 on Uranus at the time of the 2007 equinox. For vertically uniform eddy diffusion coefficients in the range 2200–2600 cm 2 s −1 , photochemical models that reproduce the observed methane emission also predict C 2 H 6 profiles that compare well with emission in the 11.6–12.5 μm wavelength region, where the υ 9 band of C 2 H 6 is prominent. Our nominal model with a uniform eddy diffusion coefficient K zz = 2430 cm 2 s −1 and a CH 4 tropopause mole fraction of 1.6 × 10 −5 provides a good fit to other hydrocarbon emission features, such as those of C 2 H 2 and C 4 H 2 , but the model profile for CH 3 C 2 H must be scaled by a factor of 0.43, suggesting that improvements are needed in the chemical reaction mechanism for C 3 H x species. The nominal model is consistent with a CH 3 D/CH 4 ratio of 3.0 ± 0.2 × 10 −4 . From the best-fit scaling of these photochemical-model profiles, we derive column abundances above the 10-mbar level of 4.5 + 01.1/−0.8 × 10 19 molecule-cm −2 for CH 4 , 6.2 ± 1.0 × 10 16 molecule-cm −2 for C 2 H 2 (with a value 24% higher from a different longitudinal sampling), 3.1 ± 0.3 × 10 16 molecule-cm −2 for C 2 H 6 , 8.6 ± 2.6 × 10 13 molecule-cm −2 for CH 3 C 2 H, 1.8 ± 0.3 × 10 13 molecule-cm −2 for C 4 H 2 , and 1.7 ± 0.4 × 10 13 molecule-cm −2 for CO 2 on Uranus. A model with K zz increasing with altitude fits the observed spectrum and requires CH 4 and C 2 H 6 column abundances that are 54% and 45% higher than their respective values in the nominal model, but the other hydrocarbons and CO 2 are within 14% of their values in the nominal model. Systematic uncertainties arising from errors in the temperature profile are estimated very conservatively by assuming an unrealistic “alternative” temperature profile that is nonetheless consistent with the observations; for this profile the column abundance of CH 4 is over four times higher than in the nominal model, but the column abundances of the hydrocarbons and CO 2 differ from their value in the nominal model by less than 22%. The CH 3 D/CH 4 ratio is the same in both the nominal model with its uniform K zz as in the vertically variable K zz model, and it is 10% lower with the “alternative” temperature profile than the nominal model. There is no compelling evidence for temporal variations in global-average hydrocarbon abundances over the decade between Infrared Space Observatory and Spitzer observations, but we cannot preclude a possible large increase in the C 2 H 2 abundance since the Voyager era. Our results have implications with respect to the influx rate of exogenic oxygen species and the production rate of stratospheric hazes on Uranus, as well as the C 4 H 2 vapor pressure over C 4 H 2 ice at low temperatures.

The latitudinal variation of Saturn's tropospheric composition (NH3, PH3 and AsH3) and aerosol properties (cloud altitudes and opacities) are derived from Cassini/VIMS 4.6-5.1μm thermal emission spectroscopy on the planet's nightside (April 22, 2006). The gaseous and aerosol distributions are used to trace atmospheric circulation and chemistry within and below Saturn's cloud decks (in the 1- to 4-bar region). Extensive testing of VIMS spectral models is used to assess and minimise the effects of degeneracies between retrieved variables and sensitivity to the choice of aerosol properties. Best fits indicate cloud opacity in two regimes: (a) a compact cloud deck centred in the 2.5-2.8bar region, symmetric between the northern and southern hemispheres, with small-scale opacity variations responsible for numerous narrow light/dark axisymmetric lanes; and (b) a hemispherically asymmetric population of aerosols at pressures less than 1.4bar (whose exact altitude and vertical structure is not constrained by nightside spectra) which is 1.5-2.0× more opaque in the summer hemisphere than in the north and shows an equatorial maximum between ±10° (planetocentric).Saturn's NH3 spatial variability shows significant enhancement by vertical advection within ±5° of the equator and in axisymmetric bands at 23-25°S and 42-47°N. The latter is consistent with extratropical upwelling in a dark band on the poleward side of the prograde jet at 41°N (planetocentric). PH3 dominates the morphology of the VIMS spectrum, and high-altitude PH3 at p

Thunderstorm activity has been observed on Saturn via radio emissions from lightning discharges and optical detections of the lightning flashes on the planets nightside. Thunderstorms provide extreme environments in which specific atmospheric chemistry can be induced - namely through energy release via lightning discharges, and fast vertical transport resulting in rapid advection of tropospheric species. It is thus theorised that certain atmospheric trace species such as C 2H 2, HCN, and CO can be generated in the troposphere by large bursts of energy in the form of lightning, and transported upward towards the upper troposphere by the extreme dynamics of thunderstorms, where they should be observable by satellite instruments. In this work, high-spectral-resolution Cassini/CIRS observations from October 2005 through April 2009 are used to study whether there is an observable increase in upper tropospheric acetylene in regions of known normal thunderstorm activity. Using both individual measurements in which there is known thunderstorm activity, as well as large coadditions of data to study latitudinal-dependencies over the full disc, no systematic enhancement in upper tropospheric (100 mbar) C 2H 2 was detected around regions in which there are known occurrences of normally sized (2000 km) thunderstorms, or in normally sized thunderstorm-prone regions such as 40°S. It is likely that the magnitude of the enhancement theorised is too generous or that enhancements are not advected into the upper troposphere as vertical mixing rates in models would suggest, since Cassini/CIRS can only detect C 2H 2 above the 200 mbar level - although the massive northern hemisphere thunderstorm of 2010/2011 seems able to decrease stratospheric concentrations of C 2H 2. From this, it can be asserted that lightning from normal thunderstorm activity cannot be the key source for upper tropospheric C 2H 2 on Saturn, since the upper-tropospheric concentrations retrieved agree with the concentrations stemming from the photolysis of CH 4 (23 ppbv) from solar radiation penetrating through the Saturnian atmosphere, with an upper limit for lightning-induced C 2H 2 volume mixing ratio of 10 -9. © 2012 Elsevier Ltd. All rights reserved.

We present an intercomparison of Saturn’s stratosphere between Voyager 1-IRIS observations in 1980 and Cassini-CIRS observations in 2009 and 2010. Over a saturnian year (∼29.5 years) has now passed since the Voyager flybys of Saturn in 1980/1981. Cassini observations in 2009/2010 capture Saturn in the same season as Voyager observations (just after the vernal equinox) but one year later. Any differences in Saturn’s atmospheric properties implied by a comparison of these two datasets could therefore reveal the extent of interannual variability. We retrieve temperature and stratospheric acetylene and ethane concentrations from Voyager 1-IRIS ( Δ ν = 4.3 cm - 1 ) observations in 1980 and Cassini-CIRS ( Δ ν = 15.5 cm - 1 ) ‘FIRMAP’ observations in 2009 and 2010. We observe a difference in temperature at the equator of 7.1 ± 1.2 K at the 2.1-mbar level that implies that the two datasets have captured Saturn’s semiannual oscillation (SSAO) in a slightly different phase suggesting that its period is more quasi-semiannual. Elevated concentrations of acetylene at 25°S in 1980 with respect to 2010 imply stronger downwelling at the former date which may also be explained by a difference in the phase of the SSAO and its dynamical forcing at low latitudes. At high-southern and high-northern latitudes, stratospheric temperatures and hydrocarbon concentrations appear elevated in 1980 with respect to 2009/2010. This could be an artefact of the low signal-to-noise ratio of the corresponding observations but might also be explained by increased auroral activity during solar maximum in 1980.

On 2007 December 16-17, spectra were acquired of the disk of Uranus by the Spitzer Infrared Spectrometer (IRS), ten days after the planet's equinox, when its equator was close to the sub-Earth point. This spectrum provides the highest-resolution broad-band spectrum ever obtained for Uranus from space, allowing a determination of the disk-averaged temperature and molecule composition to a greater degree of accuracy than ever before. The temperature profiles derived from the Voyager radio occultation experiment by Lindal et al. (Lindal, G.F., Lyons, J.R., Sweetnam, D.N., Eshleman, V.R., Hinson, D.P. [1987]. J. Geophys. Res. 92, 14987-15001) and revisions suggested by Sromovsky et al. (Sromovsky, L.A., Fry, P.A., Kim, J.H. [2011]. Icarus 215, 292-312) that match these data best are those that assume a high abundance of methane in the deep atmosphere. However, none of these model profiles provides a satisfactory fit over the full spectral range sampled. This result could be the result of spatial differences between global and low-latitudinal regions, changes in time, missing continuum opacity sources such as stratospheric hazes or unknown tropospheric constituents, or undiagnosed systematic problems with either the Voyager radio-occultation or the Spitzer IRS data sets. The spectrum is compatible with the stratospheric temperatures derived from the Voyager ultraviolet occultations measurements by Herbert et al. (Herbert, F. et al. [1987]. J. Geophys. Res. 92, 15093-15109), but it is incompatible with the hot stratospheric temperatures derived from the same data by Stevens et al. (Stevens, M.H., Strobel, D.F., Herbert, F.H. [1993]. Icarus 101, 45-63). Thermospheric temperatures determined from the analysis of the observed H2 quadrupole emission features are colder than those derived by Herbert et al. at pressures less than ∼1 μbar. Extrapolation of the nominal model spectrum to far-infrared through millimeter wavelengths shows that the spectrum arising solely from H2 collision-induced absorption is too warm to reproduce observations between wavelengths of 0.8 and 3.3 mm. Adding an additional absorber such as H2S provides a reasonable match to the spectrum, although a unique identification of the responsible absorber is not yet possible with available data. An immediate practical use for the spectrum resulting from this model is to establish a high-precision continuum flux model for use as an absolute radiometric standard for future astronomical observations. © 2014.

The surface modification of U, UFe 2 by exposition in air at room temperature and at 63°C was studied by secondary ion mass spectroscopy (SIMS), time of flight-secondary ion mass spectroscopy (ToF-SIMS), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) with variable detection angle. For the two systems, a first layer of carbon contamination, followed by complex oxide layer constitutes the surface. For U, the oxide layer is composed of a mixture of UO 2 and UO 2+ x with x maximal at the surface. In UFe 2 , the oxide layer is composed of a mixture of UO 2 and UO 2+ x , oxidised iron in Fe2+ and Fe3+ chemical states (more probably FeO), a few percent of a ternary oxide UFeO 4 , and less than 1% of uranium carbide. A surface segregation of uranium is shown in UFe 2 .

Results from measurements of K-shell ionization cross sections of the elements Cr, Ni and Cu by electron impact with energies in the range 6.5-40 keV are presented. Cross sections were obtained by measuring characteristic x-rays emitted from (1-6 nm thick) films of the studied elements deposited on self-supporting carbon backing films. The procedure yields relative cross sections with uncertainties of the order of 2%. Transformation to absolute units increases the uncertainties to about 10%. Our results are compared with those from other groups and with two calculations based on the first Born approximation, which include corrections for exchange, Coulomb and relativistic effects. A simple empirical formula that accurately describes the energy dependence of the measured cross sections is provided.

Ammonia (NH 3 ) has been detected both on Saturn and Jupiter, and although its concentration and distribution has been well-studied on Jupiter, it has proven more difficult to do so on Saturn due to higher sensitivity requirements resulting from Saturn's lower atmospheric temperatures and the dominance of Saturn's phosphine which masks the ammonia signal. Using far-infrared measurements of Saturn taken by Cassini/CIRS between February 2005 and December 2010, the latitudinal variations of upper tropospheric ammonia on Saturn are studied. Sensitivity to NH 3 in the far-infrared is explored to provide estimates of temperature, para-H 2 and PH 3 , from 2.5 cm −1 spectral resolution measurements alone, 0.5 cm −1 spectral-resolution measurements alone, and 0.5 cm −1 measurements degraded to 2.5 cm −1 spectral resolution. The estimates of NH 3 from these three different datasets largely agree, although there are notable differences using the high emission angle 0.5 cm −1 data, which are asserted to result from a reduction in sensitivity at higher emission angles. For low emission angles, the 0.5 cm −1 -retrieved values of NH 3 can be used to reproduce the 2.5 cm −1 spectra with similar efficacy as those derived directly from the 2.5 cm −1 resolution data itself, and vice versa. Using low emission angle data, NH 3 is observed to have broad peak abundances at ±25° latitude, attributed to result from condensation and/or photolytic processes. Lack of data coverage at equatorial latitudes precludes analysis of NH 3 abundance at less than about 10° latitude. Noise levels are not sufficient to distinguish fine zonal features, although it seems that NH 3 cannot trace the zonal belt/zone structure in the upper troposphere of Saturn.

A wide-ranging experimental approach reveals a linear relationship between photoluminescence band peak energy and measured indium fraction for In[x]Ga[1] N epilayers with 0 < x < 0.40. We examine the dependence of the emission spectrum on composition using local measurements of the average indium content by Rutherford backscattering spectrometry, energy dispersive X-ray analysis, extended X-ray absorption fine structure and wavelength dispersed electron probe micro-analysis. Corresponding absorption and photoluminescence excitation data reveal the existence of a supplementary linear relationship between the optical bandgap and the indium fraction. Our observations provide definitive and conclusive evidence that the optical properties of InGaN do not conform to current theoretical descriptions of alloy band structure.

We previously demonstrated that in rats gastric acid secretion declines after birth and drops steeply on day 12 of life. In the present study, we investigated the part played in this decline by prostaglandin E2 (PGE2) from maternal milk. PGE2 content was first measured in the milk of untreated dams 0, 1, 5, 10, 12, 15, and 18 days after parturition. PGE2 levels were high during the first 5 days (123.5-200.5 pg/ml), declined significantly between days 10 and 15 (56.6-85.4 pg/ml; P less than 0.05), and dropped to 18.4 pg/ml on day 18. We also found that depleting milk of PGE2 prevented drop of acid secretion in 12-day-old suckling rats. Injecting lactating dams with indomethacin significantly reduced milk PGE2 content by 65% vs. milk of untreated dams. Surprisingly, administration of sesame oil, the indomethacin vehicle to the dams, increased milk PGE2 content by 182%. In the pups of the indomethacin-treated dams, acid secretion did not drop. On the contrary, in vivo basal and histamine-induced acid output rose markedly by 40 and 50%, respectively, and in vitro the net movements of 36Cl and 22Na measured in the isolated stomach indicated that active Cl- secretion had resumed. Mucosal PGE2 did not appear to be significantly involved in early development of acid secretion because administration of indomethacin to pups from untreated dams did not significantly modify the secretion measured on day 12. Data indicate that maternal milk depletion of PGE2 prevents the drop of gastric acid secretion previously observed in 12-day-old pups and suggest that in infant rats maternal PGE2 plays a physiological part in regulating acid secretion.

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Several lines of evidence, mostly derived from animal studies, indicate that changes in fetal environment may affect renal development. Besides maternal hyperglycemia or drug exposure, that were recently found to alter nephrogenesis, changes in vitamin A supply to the fetus may prove to be responsible for most of the variations in nephron number found in the population. A low vitamin A status in the fetus may be a major cause of inborn nephron deficit, either as a feature of intrauterine growth retardation or independently of growth retardation. The possibility that vitamin A status may also influence renal vascular development is raised. We suggest that low vitamin A supply to the fetus plays a role in the intrauterine programming of chronic renal disease and hypertension.

In the rat, in utero exposure to gentamicin during early renal differentiation leads to a permanent nephron deficit. The aim of the present study was to analyze, in vitro, the potential direct effect of gentamicin on early nephrogenesis.We used paired rat metanephric organ cultures from 14 (F14) or 15-day-old (F15) fetuses. We measured gentamicin accumulation into explanted metanephroi and then assessed in vitro growth in the absence or presence of the drug. Glomerular labeling and counting were performed on the whole explant to analyze the effect of antibiotics on early nephrogenesis.Growth of F14 metanephric explants in the presence of 50 micrograms of gentamicin/ml was significantly reduced from 4 days onwards as compared to controls, whereas F15 explants grown with gentamicin displayed a normal in vitro development. After 6 days of culture, F14 and F15 explants had the same accumulation of gentamicin (1 microgram/mg protein) but the gentamicin content was 4 times larger in F15 explants. At both ages, gentamicin-exposed metanephric explants exhibited a significant reduction in their number of nephrons. However, the effects of 50 micrograms of gentamicin/ml on nephrogenesis were significantly more drastic on F14 than F15 explants (35% versus 18%). When grown with 0.5 microgram of gentamicin/ml, F14 explants still exhibited a 16% defect in nephrogenesis as compared with controls, and about the same reduction was observed for cultures in the presence of 100 micrograms/ml of streptomycin and 100 IU/ml of penicillin. Incubation of F14 explants with streptomycin alone for 6 days had no effect on nephrogenesis.These results indicate that gentamicin induces a significant reduction in the number of nephrons in metanephric explants and that this effect is more important on less differentiated metanephroi. Metanephric organ culture combined with glomerular labeling represents a useful model to test the effect of various growth factors and other drugs on early nephrogenesis.

Budd-Chiari syndrome with or without portal thrombosis occurring during paroxysmal noctural hemoglobinuria is a complication with poor prognosis. We report the case of a 17-year-old woman with a double portal and hepatic venous thrombosis revealing a paroxysmal noctural hemoglobinuria and regressive with heparin. Our case suggests that the early diagnosis of the thrombosis with ultrasonography and Doppler, and rapidly initiated anticoagulant treatment may improve the prognosis of this disease.

The oxygen combining capacity of haemoglobin is tentatively assumed to be 1.3897 ml O2.g−1 Hb for a molecular weight of 64458 in man. By calculating in the same manner, dog oxygen combining capacity is found to be 13803 (1 mole Hb = 64898). Determination of the oxygen capacity/[Hb] ratio was performed in 11 dogs under two conditions simultaneously: (1) on ex vivo blood during pure oxygen inhalation; (2) on the same blood saturated in two tonometers for 20 min with pure oxygen in the first and for 5 min with pure oxygen and then 15 min with air in the second. Two main conclusions are drawn from this study, the first being theoretical: pure oxygen tonometry on the blood sampled in a subject inhaling pure oxygen for a period of 90 min allowed one to saturate completely the haemoglobin present, which is wholly active, and therefore to obtain a value for the CmaxO2Hb/[Hb] ratio of 1.383, which agrees very closely with the theoretical value. Secondly, a more practical conclusion: during pure oxygen inhalation, this theoretical value is not reached in vivo, the ratio being 1.363 (significantly lower than the theoretical one) for the sampling time of 90 min. No change was observed with respect to this value when pure oxygen tonometry was stopped after 5 min and replaced by air tonometry for the last 15 min. The latter procedure, therefore, enables one to evaluate an “actual functional oxygen capacity”. At present, coulometric method yields easy and accurate measurements of oxygen concentrations. Actual oxygen combined concentration and oxygen functional capacity are the best sources of informations concerning the oxygen transport in a subject. The theoretical value of oxygen combining capacity must be used only to evaluate the amount of active haemoglobin from oxygen functional capacity.

Nonpregnant and pregnant guinea pigs in the last third of gestation were injected intramuscularly with 4 mg of gentamicin per kg, and drug concentrations in plasma were determined by radioimmunoassay at several intervals after injection. The maximum gentamicin concentration was lower in pregnant than in nonpregnant animals (14.6 +/- 0.7 micrograms/ml versus 21.6 +/- 0.7 micrograms/ml), and the peak time occurred significantly later (0.57 +/- 0.12 h versus 0.13 +/- 0.02 h). Four hours after gentamicin injection, drug concentrations in plasma were 2.1 +/- 0.8 and 0.3 +/- 0.1 micrograms/ml in pregnant and nonpregnant animals, respectively. Pregnant animals therefore eliminated the drug from their plasma more slowly. These data provide good evidence that the kinetics of plasma gentamicin varies in pregnant females because its volume of distribution was larger in pregnant than in nonpregnant animals. Detectable but small amounts of gentamicin (less than or equal to 0.50 microgram/ml) were found in the plasma of 46 of 57 fetuses. However, no net variations in these concentrations were observed during the period between 15 min and 6 h after injection to the mother. Gentamicin concentrations were also determined in the kidneys, liver, lungs, heart, and brain of fetal guinea pigs after administration to their mothers of one daily injection of 4 mg/kg for 7 days. Gentamicin was present in all these fetal organs; however, as in the adult organs, the kidneys contained far more than any of the others. Gentamicin concentrations were not significantly different in the kidney cortex and medulla (1.79 +/- 0.16 versus 1.48 +/- 0.92 micrograms/g), indicating that, contrary to what is observed for adults, renal accumulation of gentamicin in the fetus does not occur preferentially in the cortex.

We present uniaxial stress measurements performed on the activation energies of both the deep EL2 center in GaAs (820 meV), often called « O » center, and the EL3 electronic trap (600 meV). The EL2 level is found to separate from the conduction band at a rate of (1.1 + 0.6) meV/kbar for uniaxial stress in the (100) direction and (0.8 ± 0.5) meV/kbar for uniaxial stress in the (111) direction. Both values are consistent with the pressure coefficient reported under hydrostatic conditions. The second level (EL3) exhibits more important stress dependences : (1.8 ± 0.3) meV/kbar under (100) and (2.8 ± 0.4) meV/kbar under (111) compressions, respectively.

Micropuncture samples were collected from late proximal and early distal sites of the same nephron in nondiuretic young rats aged 13-15, 19-21, and 30-39 days. Plasma ultrafiltrate (UF), tubular fluid (TF), and final urine were analyzed for Cl, Na, K, Mg, P, and Ca concentrations by electron probe. Between days 13 and 39, the proximal convoluted tubule reabsorbed a constant fraction of continuously increasing filtered loads of water, sodium, and potassium. The mean TF/UF concentration ratio for Cl in the late proximal tubule was 0.98 +/- 0.03 in the 13- to 15-day age group and increased to 1.20 +/- 0.03 in the 30- to 39-day age group. The mean TF/UF concentration ratio for Mg increased from 1.17 +/- 0.07 at 13-15 days to 2.07 +/- 0.22 at 30-39 days. The mean TF/UF concentration ratio for Ca at the end of the proximal tubule was found to be significantly lower than unity in the two youngest groups and higher in the oldest. Evidence was also found for maturation of the loop of Henle. The amounts of Cl, Na, K, and Ca reabsorbed by the loop, expressed in percent of the amount delivered, rose significantly with age. In contrast, mean Mg fractional reabsorption was already maximal in the youngest group. Phosphate reabsorption in the loop was limited in all three groups. It is concluded that in the 13- to 15-day rats 1) the fraction of the Na, K, and H2O filtered loads reabsorbed along the proximal tubule is already the same as in adult animals; 2) the proximal tubule epithelium is not able to create or maintain a transepithelial concentration gradient for Cl; and 3) the fractional reabsorption of Mg is higher than in the adult animal. It is also concluded that Cl, Na, K, and Ca transport along the loop of Henle all have the same maturation pattern but that the pattern for Mg is different.

Clearance experiments were performed with young pups born of guinea pigs given a daily injection of 4 mg of gentamicin per kg (body weight) from days 48 to 54 of gestation (term, 68 days). For 3-day-old animals, the glomerular filtration rate was similar to that measured in control guinea pigs of the same age whose mothers were given saline during the same period of gestation. The same applied to fractional excretion of water, urea, total solutes, Na, K, Ca, and Mg but not to fractional phosphate excretion, which increased significantly in the gentamicin group when compared with the controls (mean +/- standard error, 21.7 +/- 4.9 versus 7.3 +/- 1.8%; P less than 0.05; n = 6 for both). The glomerular volume of the juxtamedullary nephrons diminished by about 40%, and their proximal tubule length decreased by about 20%. The glomerular volume of the superficial nephrons also diminished, by about 30%, but their proximal tubule length did not change. The gentamicin concentration was higher in the renal cortex than in the medulla (13.1 +/- 2.6 versus 5.7 +/- 2.2 micrograms/g [dry wt]; P less than 0.01; n = 6 for each). It decreased significantly from days 3 to 20 in both tissues. No functional impairment of the kidney was found in 10-day-old animals, and normal or even supranormal morphometry of the nephrons was observed in the 20-day-old animals. It is concluded that fetal exposure to gentamicin impairs proximal tubular function in the developing animal and might also adversely affect glomerular and tubular growth. However, both the functional and morphometric impairments of nephrons are transitory.

Clearance experiments were carried out in fetal, young, and adult pigs undergoing salt loading. Kidney sections were histologically examined and the proximal tubular length, glomerular volume, and number of glomeruli were estimated. Between days 48 and 55 of gestation, the significant increase in glomerular filtration rate was proportionately higher than the concentration increase in water, total solutes, and sodium reabsorption. During this period, neither the proximal tubular length nor the glomerular volume of the juxtamedullary nephrons changed significantly. The main morphologic change took place in the superficial cortex, where new glomeruli attached to very short tubules differentiated. From day 55 to birth, the increase in water, total solutes, and sodium filtered loads was proportionately smaller than the concomitant increase in tubular reabsorption. During this phase, the major morphologic change was the significant lengthening of the proximal tubules of the juxtamedullary and superficial nephrons. These findings suggest that for water, sodium, and total solutes the maturation of superficial nephrons is accompanied by a phase of functional glomerular preponderance. Despite the differentiation of the superficial nephrons, renal handling of normally filtered glucose did not change significantly. Functional glomerulotubular coupling for water, sodium, and total solutes took place soon after birth.

Cauda equina syndrome is a rare neurological complication of ankylosing spondylitis. The specific myelographic and tomodensitometric anomalies are exemplified by the reported observation. This case is unusual by the moderation of the neurological manifestations, and especially by the absence of sphincteral disorders. The characteristic roentgenologic signs of ankylosing spondylitis are associated with a scalloped appearance of the lumbar spinal column and antecedent quiescent acromegaly.

Kidneys of newborn rats, whose mothers were given 75 mg/kg of gentamicin daily from the tenth day of gestation to its term, were examined by light and electron microscopy, as were kidneys of control rats whose mothers were given saline during the same period. In the gentamicin-treated group, the numbers of differentiated glomeruli and of S-shaped bodies counted in a median cross-section of the kidney were reduced, compared with those in the control group, but the glomerular volume was the same. In newborn rats issued from gentamicin-treated mothers, the proximal tubular lumen of the mature nephron lying in the deepest cortex was dilated, and their proximal tubular cells exhibited extensive damage, resembling that described in tubular cells of adult rats exposed to gentamicin. The subcapsular nephrogenic zone exhibited focal alterations of cytoplasmic organelle membranes, as well as nuclear lesions of several types, in cells of the nephron anlagen of the undifferentiated metanephric blastema, which were otherwise of normal appearance.

The maturation of renal function was investigated by clearance studies in 11 fetal, 9 young, and 4 adult guinea pigs undergoing salt loading (NaCl 1.5%, 75 mul min-1 100 g-1) and in 10 young and 4 adult animals under nondiuretic conditions. The fetal preparation described makes it possible to obtain two to four steady clearance periods for each animal. In the fetus, GFR increased significantly with age, but less than in the newborn. Fractional water and sodium reabsorption was generally low, and net renal secretion of potassium was observed in some cases. Fetal urine was sometimes slightly hypertonic. The effectiveness of the diuretic and natriuretic response following saline expansion was smaller in young than adult animals. The fractional excretion rate of solutes and water increased as a function of age in the young animal and the urinary Na/K concentration ratio showed a marked drop around birth. This latter observation suggests that during the first days of life the effect of saline expansion on the proximal tubule is partially blunted by enhanced sodium reabsorption from the distal nephron due to the high concentration of circulating aldosterone.

Whipple's disease is a systemic illness whose pathogenesis, which is still poorly understood, implies an infectious agent accessible to antibiotic therapy. The authors report a case which is made unusual by the manifold systemic manifestations, important eosinophilia and destructive nature of the joint lesions of the hips. The physiopathological mechanisms of ocular and cutaneous manifestations are considered. A dramatic improvement is obtained with tetracyclin.

Plasma exchange, used since 1979 in the treatment of severe rheumatoid arthritis, has been the subject of numerous publications in the recent years. According to data from a review of the literature and from our personal experience, this therapy cannot be advocated in the usual forms of rheumatoid arthritis. Because of the side-effects, the complicated technical equipment required and the short duration of therapeutic results, plasma exchange should, for the time being, be restricted to malignant forms of rheumatoid arthritis, polyvisceral exacerbations in lupus and scleroderma, and hyperviscosity syndromes in globulinopathies.

The role of magnesium in the constitution, metabolism and hormonal control of bone tissue can be deducted from what is known of its physiology. Magnesium deficiency may result in vitamin-D resistant hypocalcaemia or even biochemical signs of hypoparathyroidism, which only regress after the deficiency is corrected. Measurements of magnesium levels in blood and urine are justified when such abnormalities occur in patients with digestive disorders, predominantly alcoholism, liver diseases or malabsorption. In all other circumstances, magnesium therapy is very rarely indicated for osteo-articular diseases.

Destructive arthropathy of the shoulder is reviewed and the indications of total prothesis are briefly considered. It seems that the long term functional tolerance of destructive arthropathy of the shoulder is better than would be expected considering the radiological damage which is often substantial. The indications of shoulder prosthesis are dominated by rheumatoid polyarthritis and are infrequent in the other forms of these arthropathies.

The authors present a short series (6 cases) of serum positive rheumatoid arthritis, treated by I.M. injections (5 cases) or intra-articular injections (one case) of dismutase superoxide of bovine origin. The treatment was stopped in one case for local intolerance. Four cases treated for four months by the intramuscular route, were uninfluenced by the treatment, nor was the patient treated by the intra-articular route. The laboratory parameters (E.S.E., Rose Waaler reaction) were not modified. On the other hand, the lymphocyte fragility in culture was improved. The good tolerance of this compound in the laboratory will permit further trials in higher dosage.

Nous présentons des résultats de spectroscopie transitoire de niveaux profonds obtenus sur des matériaux homogènes de haute résistivité, silicium et sulfure de cadmium. On applique à des transitoires de photocourant entre contacts ohmiques la méthode usuelle d'analyse différentielle des transitoires de capacité utilisée pour des matériaux conducteurs. Dans le silicium N compensé la méthode permet de caractériser les pièges à minoritaires. Nous en fournissons une démonstration expérimentale directe avec un échantillon de résistivité égale à 200 Ω cm sur lequel on peut réaliser simultanément une jonction Schottky. La méthode capacitive classique révèle la présence de 3 pièges à électrons : Ec - Et = 86,156 et 550 meV alors que la photo-capacité et la photoconductivité révèlent celle d'un piège à trous : E t - Ev = 330 meV. Dans un autre échantillon de silicium, p = 104 Ω cm, le seul niveau détecté correspond à E t - Ev = 247 meV. Dans le sulfure de cadmium semi-isolant, p > 108 Ω cm, nous avons détecté la présence de 3 centres profonds et caractérisé l'un d'entre eux. Son énergie d'activation est E = 100 meV et nous pensons qu'il s'agit d'un piège à électrons.

In the mammalian foetus, the blood oxygen tension is low (PaO2 congruent to 25 Torr). The factors limiting the oxygen transfer from maternal into foetal blood are mainly the vascular arrangement and the distribution of blood flow within the placenta. The oxygen diffusion across the placenta in facilitated by a higher oxygen affinity in foetal than in maternal blood. During placental gas exchange the Bohr Effect acts in both the maternal and foetal blood to shift their oxyhaemoglobin dissociation curve so that the mean oxygen pressure gradient across the placental membrane is increased. The two main characteristics of foetal blood, a high oxygen capacity and a high oxygen affinity are well adapted to hypoxaemia since, together with a high cardiac output, they ensure an adequate oxygen supply to the foetal tissues. These characteristics of foetal blood disappear during the postnatal period in all the species thus far investigated. The change in the blood oxygen affinity which occurs in the foetus and the newborn have been attributed in some species to the presence of a foetal haemoglobin (HbF) which differs from the adult haemoglobin (HbA) either by an intrinsically higher oxygen affinity, independant of any intracellular cofactor, or by an impaired reactivity towards cofactors which alter haemoglobin oxygen affinity by directly interacting with the haemoglobin molecule (2,3 DPG, CO2). In those species in which HbF has not been shown to be structurally and functionally different from HbA, change in 2,3 DPG concentration can explain change in oxygen affinity.

Five patients with typical seropositive rheumatoid arthritis were treated by plasma exchange. All patients had severe affections resistant to conventional treatment, while in four cases the disease involved extra-articular localizations: rheumatoid nodules (3 cases), polyneuritis (1 case), skin necrosis (1 case). Each patient received between 5 and 10 plasma exchanges over a period of 3 to 4 weeks. No major complications were observed. Immediate results were very good in all cases, as shown by absence of clinical expression of the arthritis, marked regression in extra-articular symptoms, and reduction in erythrocyte sedimentation rate without parallel alterations in rheumatoid factor levels. Improvement lasted for only a few weeks in 3 patients, in one case preceded by an acutely painful episode. In the remaining 2 cases, with associated vasculitis, improvement has been sustained for a period that now exceeds one year. Results are compared with those reported in the published literature, and the mode of action and indications for plasma exchange in rheumatoid arthritis discussed.