Lysosomal dysfunction causes neurodegeneration in mucolipidosis II 'knock-in' mice.

Mucolipidosis II is a neurometabolic lysosomal trafficking disorder of infancy caused by loss of mannose 6-phosphate targeting signals on lysosomal proteins, leading to lysosomal dysfunction and accumulation of non-degraded material. However, the identity of storage material and mechanisms of neurodegeneration in mucolipidosis II are unknown. We have generated 'knock-in' mice with a common mucolipidosis II patient mutation that show growth retardation, progressive brain atrophy, skeletal abnormalities, elevated lysosomal enzyme activities in serum, lysosomal storage in fibroblasts and brain and premature death, closely mimicking the mucolipidosis II disease in humans. The examination of affected mouse brains at different ages by immunohistochemistry, ultrastructural analysis, immunoblotting and mass spectrometric analyses of glycans and anionic lipids revealed that the expression and proteolytic processing of distinct lysosomal proteins such as α-l-fucosidase, ß-hexosaminidase, α-mannosidase or Niemann-Pick C2 protein are more significantly impacted by the loss of mannose 6-phosphate residues than enzymes reaching lysosomes independently of this targeting mechanism. As a consequence, fucosylated N-glycans, GM2 and GM3 gangliosides, cholesterol and bis(monoacylglycero)phosphate accumulate progressively in the brain of mucolipidosis II mice. Prominent astrogliosis and the accumulation of organelles and storage material in focally swollen axons were observed in the cerebellum and were accompanied by a loss of Purkinje cells. Moreover, an increased neuronal level of the microtubule-associated protein 1 light chain 3 and the formation of p62-positive neuronal aggregates indicate an impairment of constitutive autophagy in the mucolipidosis II brain. Our findings demonstrate the essential role of mannose 6-phosphate for selected lysosomal proteins to maintain the capability for degradation of sequestered components in lysosomes and autophagolysosomes and prevent neurodegeneration. These lysosomal proteins might be a potential target for a valid therapeutic approach for mucolipidosis II disease.

Record high levels of atmospheric ammonia over India: Spatial and temporal analyses.

Atmospheric ammonia (NH3) is an alkaline gas and a prominent constituent of the nitrogen cycle that adversely affects ecosystems at higher concentrations. It is a pollutant, which influences all three spheres such as haze formation in the atmosphere, soil acidification in the lithosphere, and eutrophication in water bodies. Atmospheric NH3 reacts with sulfur (SOx) and nitrogen (NOx) oxides to form aerosols, which eventually affect human health and climate. Here, we present the seasonal and inter-annual variability of atmospheric NH3 over India in 2008-2016 using the IASI (Infrared Atmospheric Sounding Interferometer) satellite observations. We find that Indo-Gangetic Plains (IGP) is one of the largest and rapidly growing NH3 hotspots of the world, with a growth rate of +1.2% yr-1 in summer (June-August: Kharif season), due to intense agricultural activities and presence of many fertilizer industries there. However, our analyses show insignificant decreasing trends in annual NH3 of about -0.8% yr-1 in all India, about -0.4% yr-1 in IGP, and -1.0% yr-1 in the rest of India. Ammonia is positively correlated with total fertilizer consumption (r = 0.75) and temperature (r = 0.5) since high temperature favors volatilization, and is anti-correlated with total precipitation (r = from -0.2, but -0.8 in the Rabi season: October-February) as wet deposition helps removal of atmospheric NH3. This study, henceforth, suggests the need for better fertilization practices and viable strategies to curb emissions, to alleviate the adverse health effects and negative impacts on the ecosystem in the region. On the other hand, the overall decreasing trend in atmospheric NH3 over India shows the positive actions, and commitment to the national missions and action plans to reduce atmospheric pollution and changes in climate.

The use of contextual learning to teach biochemistry to dietetic students.

This article describes the use of contextualized and "blended" learning to teach biochemistry to dietetic students during the second year of their professional training in a 4-year undergraduate degree (Bachelor of Nutrition and Dietetics). Contextualized content was used to engage students and motivate them to learn biochemistry, which many perceived as a "hard" subject. Contextualized learning presented via problem solving exercises, case-studies, and by the use of virtual subjects in laboratory class introduced content material through real life situations highly relevant to their later clinical practice. A "blended" curriculum where content was presented in a number of different modalities (on-line, on CD, or face-to-face in small/large groups and in tutorials/lectures/laboratory class) further enhanced contextualized learning by providing a range of learning modalities catering to different student learning styles. The on-line and CD material also allowed student self-assessment of learning progress through interactive quizzes in varied assessment formats, where feedback was often immediate. Student responses to this biochemistry course have been positive with 89% finding it intellectually stimulating.

Atmospheric ammonia (NH3) emanations from Lake Natron's saline mudflats.

In a recent global analysis of satellite-derived atmospheric NH3 data, a hotspot was observed in the vicinity of Lake Natron, Tanzania. The lake is in the centre of an endorheic (limited drainage) basin and has shallow, saline-alkaline waters. Its remote location and the absence of nearby large anthropogenic sources suggest that the observed NH3 is mainly of natural origin. Here we explore 10 years of IASI NH3 satellite data and other publicly available datasets over the area to characterize the natural NH3 emissions in this unique ecosystem. Temporal analysis reveals that the emissions are episodic and linked with the lake's surface area. The largest NH3 column loadings generally occur at the end of the dry season in September-November over Lake Natron's largest mudflat, that is exposed with receding water levels. The timing is different from the agricultural dominated NH3 emissions in the wider Natron area, which peak early in the year, after the first wet season. The likely source of NH3 at Lake Natron is decomposition of organic material, either from rivers and springs or produced in the lake (plankton, bird excreta). High temperatures and alkalinity are known to promote NH3 losses from soda lakes. We formulate six processes that may explain why the largest losses are observed specifically over concentrated brines and/or exposed sediments. As a by-product, we also show that hyperspectral infrared sounders such as IASI are capable of mapping different types of evaporative minerals such as trona and thermonatrite.

Using satellite-based measurements to explore spatiotemporal scales and variability of drivers of new particle formation.

New particle formation (NPF) can potentially alter regional climate by increasing aerosol particle (hereafter particle) number concentrations and ultimately cloud condensation nuclei. The large scales on which NPF is manifest indicate potential to use satellite-based (inherently spatially averaged) measurements of atmospheric conditions to diagnose the occurrence of NPF and NPF characteristics. We demonstrate the potential for using satellite-based measurements of insolation (UV), trace gas concentrations (sulfur dioxide (SO2), nitrogen dioxide (NO2), ammonia (NH3), formaldehyde (HCHO), and ozone (O3)), aerosol optical properties (aerosol optical depth (AOD) and Ångström exponent (AE)), and a proxy of biogenic volatile organic compound emissions (leaf area index (LAI) and temperature (T)) as predictors for NPF characteristics: formation rates, growth rates, survival probabilities, and ultrafine particle (UFP) concentrations at five locations across North America. NPF at all sites is most frequent in spring, exhibits a one-day autocorrelation, and is associated with low condensational sink (AOD × AE) and HCHO concentrations, and high UV. However, there are important site-to-site variations in NPF frequency and characteristics, and in which of the predictor variables (particularly gas concentrations) significantly contribute to the explanatory power of regression models built to predict those characteristics. This finding may provide a partial explanation for the reported spatial variability in skill of simple generalized nucleation schemes in reproducing observed NPF. In contrast to more simple proxies developed in prior studies (e.g., based on AOD, AE, SO2, and UV), use of additional predictors (NO2, NH3, HCHO, LAI, T, and O3) increases the explained temporal variance of UFP concentrations at all sites.

Temporal changes in charge content of cultured chondrocytes from bovine cartilaginous tissues.

The effective charge content of the pericellular matrix of chondrocytes has been determined while the matrix is being synthesized by cells grown in culture for several weeks. The data were compared with estimates determined by chemical analysis. When measurements were performed after digestion of the matrix with papain, there was close agreement between results obtained from both techniques for proteoglycans synthesized by chondrocytes from nasal septum (a non-articular cartilage). By contrast, no such agreement was observed for proteoglycans synthesized by chondrocytes from articular cartilage, even after solubilization of the matrix with papain. While the charge calculated from chemical analysis showed a constant increase with time in culture, that measured by colloid titration showed a cyclical pattern, with maximal values occurring on days 7 and 24 of culture and a minimal value on day 14. This inability to detect all negative groups present in the matrix synthesized by articular chondrocytes would suggest the involvement of these groups in electrostatic interactions. Partial characterization of proteins synthesized by the pericellular matrix indicates that the decrease in charge content observed on day 14 could not be attributed to proteins of a particular molecular mass but possibly to an increase in the total amount of protein present. It is concluded that the marked difference in the availability of negative groups between chondrocytes cultured from articular and non-articular cartilages may reflect differences in the interaction of these negative groups with matrix components; these differences would lead to the distinct structural organization of these two cartilaginous tissues which possess different mechanical functions.

Biological and immunological characterization of human luteinizing hormone: I. Biological profile in pituitary and plasma samples after electrofocusing.

Pituitary and plasma pools from postmenopausal women and plasma pools from women at midcycle were fractionated by electrofocusing in sucrose density gradients. The biological LH activity was determined in each of the electrofocusing fractions by the use of an in vitro bioassay method. A heterogeneous profile of LH activity was found in both pituitary and plasma samples with a large proportion present within the pH range 6.5-10. In a total of 11 electrofocusing runs 7 main regions of high LH activity were found within this range with mean pI values (+/- SD) of 6.75 +/- 0.08 (n = 6), 7.33 +/- 0.08 (11), 7.80 +/- 0.09 (11), 8.23 +/- 0.10 (11), 8.81 +/- 0.04 (7), 9.17 +/- 0.05 (6) and 9.55 (2). A significantly higher proportion of LH activity was found in the midcycle plasma samples (36%) in the pH regions with mean pI values of 8.81, 9.17 and 9.55 than in postmenopausal plasma (7%) and pituitary extracts (5%). This indicates that the profile of biologically active LH in women in the fertile age is different from that present in postmenopausal women. By detailed fractionation based on narrow pH range studies and the refocusing of specific peak fractions it was shown that each of the regions studied consisted of several peaks of LH activity indicating the presence of a large number of molecular species exhibiting varying degrees of LH activity. The relative proportions of these species showed considerable differences between sources but also between samples from the same source.

Evaluation of nonideality from gel chromatographic partition coefficients. A technique with greater versatility than equilibrium dialysis.

Frontal gel chromatography has been used to measure partition coefficients which enable a quantitative evaluation of the thermodynamic nonideality of small solutes generated by the presence of high concentrations of macromolecular solutes. Equivalence of results obtained by the present method and by equilibrium dialysis is demonstrated in a comparison of results for dextran sulfate-NaCl and dextran-sorbitol systems. Interaction coefficients obtained for dextran-sorbitol and protein-polyethylene glycol 4000 systems yields results which are in reasonable agreement with those predicted on the statistical-mechanical basis of excluded volume. Because of its greater versatility in regard to the range of systems that may be studied, the frontal gel chromatographic procedure is likely to be of particular value for the quantitative characterization of thermodynamic nonideality arising from excluded volume effects in concentrated mixtures of macromolecular solutes.

[Not Available]. / Détermination de constantes d'acidité d'amidines N-N'-substituées. Relations entre les pKA et les vibrations IR - I. Acétamidines et métacrylamidines.

Changes in the ultraviolet absorption spectra with pH in aqueous solution were used to determine the pKA values of amidines. A new mathematical procedure was used to study sparingly soluble compounds. In this technique, all the experimental data are used to solve for the absorbance of the insoluble basic species and for the pKA value by a 'complex method' of optimization, which is more general than the classical least-squares method. A relationship between a double bond vibration frequency and the acidity constants of these compounds has been demonstrated.

[Diagnostic studies in carbon monoxide poisoning]. / Le dépistage de l'intoxication au monoxyde de carbone.

Origin, symptomatology, seriousness and mechanism of carbon monoxide toxicity have been reviewed as are the diagnosis based on clinical or analytical data upon which the physician may rely to search out a CO intoxication. Treatments are discussed and the best therapy is proposed in case of mild or severe poisonings.

Transport of charged macromolecules across a biological charged membrane.

The glomerular capillary wall of the kidney behaves as an electronegatively charged structure consisting of three layers, the lamina densa and the two laminae rarae, which are differently charged. Thus, a three layer model is proposed to analyse the transport of charged macromolecules across this wall. A modified Nernst-Planck equation describes the macromolecule flux across the wall and a Donnan equilibrium is assumed at each interface. For a given value of the fixed charge concentration in each layer, the local sieving coefficient of the macromolecule, i.e. the ratio between the concentrations in the filtrate and in the plasma, is calculated. A sieving curve which relates the sieving coefficient to the Einstein-Stokes radius of the macrosolute is obtained. The fixed charge concentrations in each layer are iteratively modified until simultaneous adjustment is achieved between calculated and experimental curves, for positively and negatively charged tracers and their neutral equivalent.

[Tomodensitometry of hydatid brain cysts in a child]. / Aspect tomodensitometrique du kyste hydatique intracranien chez l'enfant.

A case of an eleven year old boy with an intracranial hydadid cyst is reported. The characteristics of computerised tomography of the skull are described, and differential diagnosis of other cystic space occupying lesions of the brain as seen on computerised tomography is discussed.

The pressure and flow distribution within a filtering capillary network.

A model is developed to estimate the parameters controlling glomerular function by network analysis. The topological and dimensional parameters are obtained by reconstructing a Wistar rat glomerulus. The model allows the calculation of blood and plasma flow distribution between the glomerular branches, their contribution to filtration and the drop of intracapillary hydrostatic pressure along the network. The program adjusts the blood flow distribution and the red cells partition at divergent nodes, the afferent intracapillary hydrostatic pressure and the hydrodynamic conductance of the glomerular wall in order to satisfy the following conditions. The intracapillary pressures at a convergent node must be the same whatever pathway is followed to reach that node; the mean integrated intracapillary hydrostatic pressure and the single nephron glomerular filtration rate must equal their experimental value. Convergence is obtained applying the Newton-Raphson method.

Useful sample handlings for reversed phase high performance liquid chromatography in emergency toxicology.

Some physicochemical treatments of biological samples, before being injected into a liquid chromatograph, are discussed. The advantages of dilution, liquid and solid extraction are compared referring mainly to unpublished results. Assays of antiepileptic drugs, caffeine, theophylline, tricyclic antidepressants, valproic acid, and meprobamate are used to demonstrate the importance of sample handlings in toxicological analyses in which reversed phase high performance liquid chromatographies are applied.