Mutation in saposin D domain of sphingolipid activator protein gene causes urinary system defects and cerebellar Purkinje cell degeneration with accumulation of hydroxy fatty acid-containing ceramide in mouse

The sphingolipid activator proteins (saposins A, B, C and D) are small homologous glycoproteins that are encoded by a single gene in tandem within a large precursor protein (prosaposin) and are required for in vivo degradation of some sphingolipids with relatively short carbohydrate chains. Human patients with prosaposin or specific saposin B or C deficiency are known, and prosaposin- and saposin A-deficient mouse lines have been generated. Experimental evidence suggests that saposin D may be a lysosomal acid ceramidase activator. However, no specific saposin D deficiency state is known in any mammalian species. We have generated a specific saposin D(-/-) mouse by introducing a mutation (C509S) into the saposin D domain of the mouse prosaposin gene. Saposin D(-/-) mice developed progressive polyuria at around 2 months and ataxia at around 4 months. Pathologically, the kidney of saposin D(-/-) mice showed renal tubular degeneration and eventual hydronephrosis. In the nervous system, progressive and selective loss of the cerebellar Purkinje cells in a striped pattern was conspicuous, and almost all Purkinje cells disappeared by 12 months. Biochemically, ceramides, particularly those containing hydroxy fatty acids accumulated in the kidney and the brain, most prominently in the cerebellum. These results not only indicate the role of saposin D in in vivo ceramide metabolism, but also suggest possible cytotoxicity of ceramide underlying the cerebellar Purkinje cell and renal tubular cell degeneration.     

Light and electron microscopic analyses of immediate and late tissue damage caused by radiofrequency ablation in porcine liver

Radiofrequency ablation (RFA) is an effective procedure for localized hepatocellular carcinoma. Contrast-enhanced CT depicts the ablated area as a hypoattenuated area without hepatic blood flow; however, light microscopy does not show obvious necrosis in the ablated area. We evaluated liver tissue changes after RFA by light microscopy and electron microscopy. The normal livers of three anesthetized pigs were coagulated using RFA after laparotomy. The liver was examined immediately, and 1 week after operation by light and electron microscopy. After RFA, the liver parenchyma surrounding the needle electrode was brown in color and surrounded by a red marginal zone separate from the normal liver parenchyma. Hematoxylin-eosin staining of the central area did not show cell necrosis, and the structures of liver sinusoids, liver cell cord and the nuclei of hepatocytes were preserved. However, electron microscopic examination of tissue immediately after RFA showed destruction of mitochondria of hepatocytes and fixation of sinusoidal cells. One week later, there was a large quantity of debris in the enlarged sinusoids, in addition to irreversible destruction of hepatocyte organelles. RFA of the porcine liver causes hepatocyte damage. This damage was not evident by light microscopy but clearly identified by electron microscopy.     

RMRP mutations in Japanese patients with cartilage-hair hypoplasia

We examined 12 Japanese patients with metaphyseal chondrodysplasia (MCD) for mutations in the ribonuclease mitochondrial RNA processing gene (RMRP), and identified four novel mutations in two patients with typical and atypical cartilage-hair hypoplasia (CHH), a form of MCD characterized by extra-skeletal manifestations including hypoplastic hair and defective immunity. A patient with typical CHH had a 17-bp duplication at +3 and a de novo 182G > A. The other patient with atypical CHH had a 17-bp insertion at -20 and a 218A > G. Expression analysis revealed that the allele with this insertion mutation in the promoter region silenced the gene. Spectrum analysis of the mutations and polymorphisms in RMRP showed marked difference between the Japanese and other ethnic groups. Such ethnic and phenotypic difference should be taken into account in mutation analysis of the gene.     

Heterogeneous Expression and Release of CD14 by Human Gingival Fibroblasts: Characterization and CD14-Mediated Interleukin-8 Secretion in Response to Lipopolysaccharide

To identify the role in periodontal inflammatory diseases of human gingival fibroblasts (HGF), the major constituents of gingival tissue, the expression of CD14, a possible lipopolysaccharide (LPS) receptor, and the release of soluble CD14 (sCD14) by HGF were examined. Among the HGF samples from the nine donors tested, more than 50% of the HGF from five donors expressed CD14 but less than 20% of HGF from the other four donors did so, as determined by flow cytometric analysis. The CD14 expression on the cell surface was correlated with the expression of CD14 mRNA. The HGF and skin and lung fibroblasts tested expressed no CD18, which indicates that fibroblasts do not possess other LPS receptors, such as CD11b/CD18 and CD11c/CD18. The CD14 expression by the HGF was decreased after subculturing and was highest at the confluent stage of culture. The treatment of high-CD14-expressing (CD14^high) HGF with phosphatidylinositol-phospholipase C reduced CD14 expression; this result and the increase in a 55-kDa CD14 indicate that the membrane CD14 (mCD14) on the HGF may be a 55-kDa glycosylphosphatidylinositol-anchored protein. CD14^high HGF spontaneously released 48- and 57-kDa sCD14. The total release of sCD14 by the HGF was augmented by gamma interferon and Escherichia coli LPS in accordance with the increased expression of mCD14. The CD14^high HGF secreted interleukin-8 in response to LPS, and the secretion was completely inhibited by anti-CD14 antibody. These results suggest that (i) HGF consist of populations that are heterogeneous on the basis of different levels of expression of CD14 and (ii) CD14^high HGF secrete inflammatory cytokines in response to LPS via CD14.     

Quantitative distribution of rat brain monoamine oxidase A by [14C]clorgyline autoradiography

The distribution of functionally active monoamine oxidase type A (MAO-A) was investigated by in vivo quantitative autoradiography using [¹⁴C]clorgyline in normal, conscious rat brain. [¹⁴C]clorgyline was synthesized by the methylation reaction of N-desmethylclorgyline using [¹⁴C]methyliodide. Sixty minutes after [¹⁴C]clorgyline administration (1.58 MBq/animal i.v.), the brains were removed and prepared for autoradiography by washing the brain sections with 5% trichloroacetic acid solution to remove the nonbinding free tracer. The amount of MAO-A was calculated from the regional acid-insoluble tissue radioactivity and the specific activity of the tracer. The highest amount of MAO-A (5.84 nmol/g tissue) was found in the locus coeruleus. The interpeduncular nucleus, habenular nucleus, fasciculus retroflexus, and solitary tract nucleus possessed over 1.6 nmol/g tissue of MAO-A. Among 23 regions of interest, the lowest amount of MAO-A (0.37 nmol/g tissue) was found in the globus pallidus. The findings of this study suggest that the pattern of MAO-A parallels both in neuroanatomical distribution and in density that of norepinephrine and serotonin innervation. The MAO-A concentration was, however, relatively low in the dopamine-related areas. This corresponded to the previous results obtained by histochemical analysis. In addition, among the white matter structures, a high amount of MAO-A was found specifically in the fasciculus retroflexus.     

Increased release of glucuronoxylomannan antigen and induced phenotypic changes in Trichosporon asahii by repeated passage in mice

Clinically important fungi such as Candida albicans and Cryptococcus neoformans are known to undergo phenotypic changes after repeated subculture or passages in vivo. However, there are no reports describing this phenomenon in Trichosporon species. This study investigated whether in-vivo passages of environmental isolates of Trichosporon asahii in mice changes their phenotype; three environmental isolates and 14 clinical isolates (from deep-seated infections) were used. The shape of the colony and cell type were observed, and the titre of glucuronoxylomannan (GXM) antigen and concentration of (1-->3)-beta-D-glucan were measured for each isolate. Changes in these features were also examined after three passages of the environmental isolates in mice. The shape of colonies and cell types were clearly different in environmental and clinical isolates. Furthermore, the clinical isolates released significantly higher levels of GXM antigen than environmental isolates (titre: log2 9.4 SD 0.7 versus log2 5.4 SD 1.4). The phenotype of passaged isolates was significantly different from the original environmental isolates with respect to the morphology of colonies and cell type and GXM release (titre: log2 10.0 SD 0.7 versus log2 5.4 SD 1.4). These results suggest that the phenotypic changes in T. asahii occur as a result of in-vivo passages. This process may allow a proportion of the fungal population to escape eradication by the host immune system, as GXM antigen is considered to protect the fungi against phagocytosis by polymorphonuclear leucocytes and monocytes in vivo.     

Somatic mosaicism of CAG repeat in dentatorubral-pallidoluysian atrophy (DRPLA)

An unstable expansion of CAG repeat in the coding region ofthe DRPLA gene on chromosome 12p is the mutation specific forhereditary dentatorubralpallidoluysian atrophy (DRPLA). We studiedthe CAG expansion in brain and other tissues from six unre latedDRPLA patients. The CAG repeat lengths showed distinct difterencesbetween tissues. The sizes of the CAG expansion in various regionsof the brain except the cerebellum were generally larger byseveral repeats than in other peripheral tissues. Brain samplesshowed greater variation of the expansion compared with othertissues, but neither the size of the CAG expansion nor the degreeof CAG repeat variation parallels the detailed findings of neuropathologicalinvolvement. We conclude that somatic instabilities of the CAGrepeat cause tissue variability of the CAG repeat size in DRPLAbut other region or cell type-specific factors would be involvedto explain the selectivity of cell damage in DRPLA.     

HTL V-I from Iranian Mashhadi Jews in Israel is phylogenetically related to that of Japan,India, and South America rather than to that of Africa and Melanesia

A new endemic focus of human T-lymphotropic virus type I (HTL V-I) was recently reported among Mashhadi Jews, a group of immigrants from northeastern Iran to Israel. We extracted DNAs from fresh peripheral blood mononuclear cells (PBMCs) and/or gargle mouthwash from 10 HTL V-I carriers, who consisted of members of one family, and HTL V-I-associated myelopathy (HAM) and adult T-cell leukemia (ATL) patients. Long terminal repeat (LTR) regions of proviral DNAs were sequenced and analyzed phylogenetically. In a phylogenetic tree, all the Mashhadi HTL V-I isolates belonged to subtype A, one of the three subtypes of the cosmopolitan type of HTL V-I, and made a tight cluster distinct from the other isolates of subtype A from Japan, India, the Caribbean Basin, and South America. Although a few nucleotide substitutions were observed among the clones sequenced, no characteristic sequence variation was found in different disease manifestations, even in one family or different sources of DNA preparation.     

Claudin‐7 Expressed on Lateral Membrane of Rat Epididymal Epithelium does not Form Aberrant Tight Junction Strands

Claudins are integral membrane proteins at tight junctions (TJs) and form TJ strands. In the present study, we found that claudin‐7 was localized along the entire lateral membranes of epididymal epithelium, including the apical junctional region throughout the epididymis, but claudin‐8 was restricted to the apical junctional region. This finding raises the possibility that aberrant TJ strands may be formed on lateral membranes. Thus, we focused on examining whether TJ strands exist on lateral membranes of epididymal epithelium. Freeze‐fracture electron microscopy showed that aberrant TJ strands were observed in only a few principal cells in all segments of the epididymis except for the initial segment, indicating that the occurrence of aberrant strands is very rare. Aberrant TJ strands were smooth and not subdivided into individual particles in the protoplasmic face, and complementary grooves in the extracellular face were almost free of particles. Aberrant TJ strands in the distal caput and corpus epididymis were accompanied by many vesicle‐like structures but those in the proximal caput and cauda epididymis were not. These results suggest that most of claudin‐7 in lateral membranes may exist in a nonpolymerized form and may play some different roles other than the formation of TJ strands, for example, in the formation of a pool of claudin proteins or in the reinforcement of cell adhesion. Anat Rec, 1431‐1438, 2007. © 2007 Wiley‐Liss, Inc.