Evaluation of manganese uptake and toxicity in mouse brain during continuous MnCl2 administration using osmotic pumps.

Manganese is a vital element and cofactor of many key enzymes, but it is toxic at high levels, causing pronounced disturbances in the mammalian brain. Magnetic resonance imaging (MRI) studies using manganese ions as a paramagnetic contrast agent are often limited by the neurotoxicity of Mn(2+) . In this work, we have explored a new in vivo model to study Mn(2+) uptake, distribution and neurotoxicity in mice by subcutaneous implantation of mini-osmotic pumps delivering MnCl(2) continuously for 21 days. Fractionated injections can reduce the toxicity; however, constant administration at very low doses using osmotic pumps caused a substantial effect on the T(1) contrast in MRI while reducing toxicity. Manganese-enhanced MRI documented fast but reversible Mn(2+) deposition largely in glomerular and mitral cell layers of the olfactory bulb, in the CA3 area of the hippocampus, and in the gray matter of the cerebellum. Mn(2+) accumulated as early as the first days after implantation, with a fast dispersal 9 days after stopping a 12-days Mn(2+) exposure. Prominent Mn(2+) accumulation was also seen in salivary glands and in the endocrine thyroid and posterior pituitary gland. These structures with enhanced Mn(2+) accumulation correlated well with those showing high expression of the secretory pathway Ca(2+) /Mn(2+) -ATPase (SPCA1), i.e. a transporter that could take part in Mn(2+) detoxification. Our new experimental model for continuous low-dosage administration of Mn(2+) is an easy alternative for enhancing Mn(2+) -based contrast in MEMRI studies, and might provide insight into the etiology of neuropathologies resulting from chronic Mn(2+) exposure in vivo.

Distribution of the intracellular Ca(2+)-ATPase isoform 2b in pig brain subcellular fractions and cross-reaction with a monoclonal antibody raised against the enzyme isoform.

The presence and distribution of sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) isoform 2b in microsomes and other subcellular fractions isolated from pig brain has been demonstrated by the combined use of a specific antibody raised against the SERCA2b isoform and ATP phosphorylation experiments. All subcellular fractions show an approximately 110 kDa phosphorylated protein, the band intensity being stronger in microsomes. Preliminary treatment of the samples with trypsin generates two phosphorylated fragments of about 57 and 33 kDa in the presence of Ca(2+). The observed fragments are typical trypsinized products of the SERCA2b isoform. The monoclonal antibody Y/1F4 raised against the sarcoplasmic reticulum Ca(2+)-ATPase (isoform 1) binds to the 110 kDa band in membranes isolated from brain. The binding was stronger in microsomes than in other fractions. Furthermore, this antibody also recognizes a clear band at around 115 kDa. This band is always stronger in plasma membrane than in synaptosomes or microsomes and is unaffected by trypsin. Phosphorylation studies in the absence of Ca(2+) suggest that the 115 kDa protein is not a Ca(2+)-ATPase.

Membranoproliferative glomerulonephritis with polyarteritis: a case report.

A case of membranoproliferative glomerulonephritis with polyarteritis is described. The patient was a 68 year old male who had the disease for about four months. A kidney biopsy specimen taken just before the patient died was studied by light, immunofluorescence, and electron microscopy. Splitting of the basement membrane, IgG, IgA, BlC, Clq, fibrinogen, and electron dense deposits were found in the glomeruli. It is considered that perhaps some cases of membranoproliferative glomerulonephritis are produced by circulating immune complexes.

Quantitative studies of immunofluorescent staining. Relationships of characteristics of unabsorbed antihuman IgG conjugates to their specific and non-specific staining properties in an indirect test for antinuclear factors.

Reproducible titres of indirect immunofluorescent (IF) staining with antinuclear factor (ANF)-containing sera could be obtained with different antihuman IgG conjugates by quantitative adjustments of their characteristics. Conversely, one ANF yielded a broad range of ANF titre (80-640) upon appropriate adjustments of the conjugate characteristics. The same and related characteristics of the conjugates also afforded a basis for quantitatively defining the conditions under which non-specific staining (NSS) appeared. The salient characteristics of the anti-IgG conjugates include: (1) their strength of antiglobulin (expressed as units/ml of precipitating antibody or mug antibody N/ml); (2) their apparent fluorescein concentration (in mug F/ml); (3) their protein concentration (in mg/ml). Optical and immunologic sensitivity ratios are calculated from these conjugate characteristics. Optical sensitivity (expressed as fluorescein concentration to protein concentration (F/P) ratios), immunological sensitivities (expressed as units/1% protein) and the dilution employed serve to characterize quantitatively anti-IgG conjugates adequately to define their specific and non-specific staining properties.