Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth.

The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu's boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.

An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime.

The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2's Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu's surface age.

Characterization of anti-crotalic antibodies.

Crotalus durissus terrificus, C. d. collilineatus, C. d. cascavella and C. d. marajoensis are responsible minor but severe snake bites in Brazil. The venoms of these snakes share the presence of crotoxin, a neurotoxin comprising of two associated components, crotapotin and phospholipase A2 (PLA2). Treatment of the victims with specific antiserum is the unique effective therapeutic measure. The ability of anti-Crotalus antisera produced by the routine using crude venom to immunize horses or purified crotoxin and PLA2 as individual immunogens was compared. Antisera obtained from horses immunized with C. durissus terrificus crude venom were able to recognize and neutralize not only the toxins presents in C. durissus terrificus, but also the ones present in the venoms from C. d. collilineatus, C. d. cascavella and C. d. marajoensis. Antisera from horses immunized with individual crotoxin or PLA2, although in lesser titers, were also able of recognizing the toxins in all four Crotalus species and neutralize the lethality of the C. d. terrificus venom.

Recovery of corneal irregular astigmatism, ocular higher-order aberrations, and contrast sensitivity after discontinuation of overnight orthokeratology.

AIMS: To examine prospectively the recovery of various parameters after discontinuation of overnight orthokeratology. METHODS: Seventeen subjects undergoing orthokeratology for 12 months were examined. Refraction, corneal topography, wavefront aberrometry, a visual acuity test and a contrast sensitivity test were performed at baseline, 12 months after commencement of the procedure, and 1 week and 1 month after discontinuation of the treatment. Asymmetry and higher-order irregularity components were calculated using a Fourier analysis of the corneal topography data. Contrast sensitivity was assessed at four spatial frequencies, and the area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS: Orthokeratology significantly reduced manifest refraction (p<0.0001, Dunnett test) and significantly improved uncorrected visual acuity (UCVA) at 12 months after commencement of the procedure (p<0.0001). Asymmetry and higher-order irregularity components increased significantly (p<0.0001, p = 0.0032, respectively), and third- and fourth-order aberrations also increased significantly (p<0.0001). The treatment resulted in significant decreases in AULCSF (p = 0.0004). After discontinuing lens wear, all parameters, such as refraction, UCVA, asymmetry, higher-order irregularity, third-order aberration, fourth-order aberration and AULCSF, returned to the baseline level at 1 week. CONCLUSION: This study confirmed that the effect of orthokeratology is completely reversible in light of optical quality of the eye and quality of vision as well as refraction and visual acuity.

Higher-order wavefront aberration and letter-contrast sensitivity in keratoconus.

AIMS: To evaluate the relation between higher-order aberration of the eye and contrast sensitivity function in eyes with keratoconus. METHODS: In 22 eyes of 14 patients with keratoconus (age 30.5+/-8.4 years, means+/-SD) and 26 eyes of 13 normal controls (age 29.2+/-6.7 years), ocular higher-order wavefront aberration for a 6-mm pupil was measured with the Hartmann-Schack aberrometer (KR-9000 PW, Topcon). The root mean square (RMS) of third- and fourth-order Zernike coefficients was used to represent higher-order aberrations. The letter-contrast sensitivity was examined using the CSV-1000LV contrast chart (Vector Vision). RESULTS: In the keratoconus group, the letter-contrast sensitivity showed significant correlation with third-order (Spearman's correlation coefficient r=-0.736, P<0.001) and fourth-order aberrations (r=-0.464, P<0.05). There was borderline correlation between log MAR BSCVA and third-order (r=0.413, P=0.070) and fourth-order aberrations (r=0.394, P=0.086). In the normal group, the letter-contrast sensitivity had no significant correlation with third-order (r=-0.170, P=0.411) and fourth-order aberrations (r=-0.088, P=0.673), and log MAR best spectacle-corrected visual acuity (BSCVA) showed no correlation with third-order (r=0.063, P=0.762) and fourth-order aberrations (r=-0.282, P=0.165). CONCLUSIONS: In eyes with keratoconus, there is significant correlation between contrast sensitivity and ocular higher-order wavefront aberrations.

Changes in higher-order aberrations after scleral buckling surgery for rhegmatogenous retinal detachment.

PURPOSE: To evaluate changes in higher-order aberrations (HOAs) after scleral buckling surgery for the treatment of rhegmatogenous retinal detachment (RD). DESIGN: Prospective observational comparative case series. PARTICIPANTS: The study included 67 eyes of 67 rhegmatogenous RD patients undergoing scleral buckling surgery, and the fellow normal eyes comprised the control group. Twenty-seven eyes were treated with the segmental buckling procedure and 40 eyes received the encircling buckling procedure alone. METHODS: Hartmann-Shack wavefront analysis was performed at 2 weeks, 1 month, and 3 months postoperatively. MAIN OUTCOME MEASURE: Time course of changes in HOAs. RESULTS: Scleral buckling surgery significantly increased HOAs at 2 weeks (P<0.0001), 1 month (P<0.0005), and 3 months (P<0.05) postoperatively as compared with the control group. At 3 months postoperatively, the HOAs were significantly lower in the encircling group than in the segmental buckling group (P<0.05). The vertical coma (Zernike Z(3)(-1)) became negative (significantly lower than zero, P<0.01) in patients who received segmental buckling in the upper quadrant. The ocular HOAs and logarithm of the minimum angle of resolution best-corrected visual acuity significantly correlated at 3 months postoperatively (third-order root mean square [RMS]: r = 0.445, P<0.0005; fourth-order RMS: r = 0.489, P<0.0001). CONCLUSIONS: Scleral buckling surgery significantly increased HOAs. The segmental buckling procedure increased the HOAs to a greater extent and for a longer duration than the encircling procedure. The direction of coma aberration corresponded to the location of the segmental buckle. The increase in HOAs can be one of the factors responsible for visual disturbances after scleral buckling surgery.

Changes in corneal topography after 25-gauge transconjunctival sutureless vitrectomy versus after 20-gauge standard vitrectomy.

PURPOSE: To evaluate the changes in regular and irregular corneal astigmatism after 25-gauge transconjunctival sutureless vitrectomy and 20-gauge standard vitrectomy. DESIGN: Prospective observational comparative case series. PARTICIPANTS: Thirty-two eyes of 32 patients undergoing 25-gauge transconjunctival sutureless vitrectomy and 25 eyes of 24 patients undergoing 20-gauge standard vitrectomy. METHODS: Corneal topography was obtained preoperatively and at 2 weeks and 1 month postoperatively. MAIN OUTCOME MEASURES: The dioptric data of the central 3-mm zone of the cornea were decomposed using Fourier harmonic analysis into spherical power, regular astigmatism, asymmetry, and higher-order irregularity. RESULTS: None of the 4 Fourier indices changed throughout the observation period in the 25-gauge group. In the 20-gauge group, regular astigmatism, asymmetry, and higher-order irregularity were increased significantly at 2 weeks after vitrectomy (P<0.05, Wilcoxon signed-ranks test) and returned to preoperative levels by 1 month. The spherical power in the 20-gauge group did not change after surgery. For regular astigmatism, asymmetry, and higher-order irregularity, the 20-gauge group showed significantly greater surgically induced changes than the 25-gauge group (P<0.05, Mann-Whitney U test). CONCLUSIONS: Twenty-five-gauge transconjunctival sutureless vitrectomy does not induce significant changes in corneal topography and exerts little influence on the optical quality of the cornea.

Influence of tilt and decentration of scleral-sutured intraocular lens on ocular higher-order wavefront aberration.

AIM: To investigate the influence of tilt and decentration of scleral-sutured intraocular lenses (IOLs) on ocular higher-order wavefront aberrations. METHODS: In 45 eyes of 36 patients who had undergone scleral suture fixation of posterior chamber IOL, tilt and decentration of IOLs were determined by Scheimpflug videophotography, and higher-order aberration for a 4-mm pupil was measured using the Hartmann-Shack aberrometer. In another 100 eyes of 100 patients after standard cataract surgery with posterior chamber IOL implantation, ocular higher-order aberration was measured. RESULTS: In eyes with scleral-sutured IOL, the mean (SD) tilt angle and decentration were 4.43 degrees (3.02 degrees ) and 0.279 (0.162) mm, respectively. Ocular coma-like aberration in the sutured IOL group was 0.324 (0.170) microm, which was significantly greater than that of the standard cataract surgery group (0.169 (0.061) microm, p<0.001, Student's t test). No significant difference was found in ocular spherical-like aberration between the sutured IOL group (0.142 (0.065) microm) and standard surgery group (0.126 (0.033) microm; p = 0.254). In the sutured IOL group, IOL tilt significantly correlated with ocular coma-like aberration (Pearson's correlation coefficient r = 0.628, p<0.001), but no significant correlation was found between IOL tilt and ocular spherical-like aberration (r = 0.222, p = 0.175). The IOL tilt did not correlate with corneal coma-like (r = 0.289, p = 0.171) and spherical-like (r = 0.150, p = 0.356) aberrations. The IOL decentration did not correlate with any higher-order aberrations. CONCLUSION: In eyes with scleral-sutured posterior chamber IOL, tilting of the lens induces considerable amount of ocular coma-like aberrations.

Cellular uptake of amelogenin, and its localization to CD63, and Lamp1-positive vesicles.

Proteins of the developing enamel matrix include amelogenin, ameloblastin and enamelin. Of these three proteins amelogenin predominates. Protein-protein interactions are likely to occur at the ameloblast Tomes' processes between membrane-bound proteins and secreted enamel matrix proteins. Such protein-protein interactions could be associated with cell signaling or endocytosis. CD63 and Lamp1 are ubiquitously expressed, are lysosomal integral membrane proteins, and localize to the plasma membrane. CD63 and Lamp1 interact with amelogenin in vitro. In this study our objective was to study the molecular events of intercellular trafficking of an exogenous source of amelogenin, and related this movement to the spatiotemporal expression of CD63 and Lamp1 using various cell lineages. Exogenously added amelogenin moves rapidly into the cell into established Lamp1-positive vesicles that subsequently localize to the perinuclear region. These data indicate a possible mechanism by which amelogenin, or degraded amelogenin peptides, are removed from the extracellular matrix during enamel formation and maturation.

Multicentric lymphoma with metastasis in the central nervous system in a dog

Linfoma multicêntrico foi diagnosticado em um cão com dois anos de idade que apresentava insuficiência respiratória, aumento de volume abdominal (ascite) e linfoadenopatia generalizada. O exame imunoistoquímico revelou origem de células T com expressão CD3+ e CD79-. Após cinco semanas, o cão apresentou déficits neurológicos progressivos, sendo identificada a presença de linfócitos neoplásicos no líquor. O exame histopatológico demonstrou invasão de células neoplásicas no baço, linfonodos, cérebro e cerebelo.

Structural organization and cellular localization of tuftelin-interacting protein 11 (TFIP11).

Tuftelin-interacting protein (TFIP11) was first identified in a yeast two-hybrid screening as a protein interacting with tuftelin. The ubiquitous expression of TFIP11 suggested that it might have other functions in non-dental tissues. TFIP11 contains a G-patch, a protein domain believed to be involved in RNA binding. Using a green fluorescence protein tag, TFIP11 was found to locate in a novel subnuclear structure that we refer to as the TFIP body. An in vivo splicing assay demonstrated that TFIP11 is a novel splicing factor. TFIP11 diffuses from the TFIP body following RNase A treatment, suggesting that the retention of TFIP11 is RNA dependent. RNA polymerase II inhibitor (-amanitin and actinomycin D) treatment causes enlargement in size and decrease in number of TFIP bodies, suggesting that TFIP bodies perform a storage function rather than an active splicing function. The TFIP body may therefore represent a new subnuclear storage compartment for splicing components.

Linfoma multicêntrico com metástase no sistema nervoso central em cão. Relato de caso

O artigo não apresenta resumo.

Vesicular trafficking machinery, the actin cytoskeleton, and H+-K+-ATPase recycling in the gastric parietal cell.

Gastric HCl secretion by the parietal cell involves the secretagogue-regulated re-cycling of the H+-K+-ATPase at the apical membrane. The trafficking of the H+-K+-ATPase and the remodelling of the apical membrane during this process are likely to involve the co-ordination of the function of vesicular trafficking machinery and the cytoskeleton. This review summarizes the progress made in the identification and characterization of components of the vesicular trafficking machinery that are associated with the H+-K+-ATPase and of components of the actin-based cytoskeleton that are associated with the apical membrane of the parietal cell. Since many of these proteins are also expressed at the apical pole of other epithelial cells, the parietal cell may represent a model system to characterize the protein- protein interactions that regulate apical membrane trafficking in many other epithelial cells.

Clathrin in gastric acid secretory (parietal) cells: biochemical characterization and subcellular localization.

Clathrin from H-K-ATPase-rich membranes derived from the tubulovesicular compartment of rabbit and hog gastric acid secretory (parietal) cells was characterized biochemically, and the subcellular localization of membrane-associated clathrin in parietal cells was characterized by immunofluorescence, electron microscopy, and immunoelectron microscopy. Clathrin from H-K- ATPase-rich membranes was determined to be comprised of conventional clathrin heavy chain and a predominance of clathrin light chain A. Clathrin and adaptors could be induced to polymerize quantitatively in vitro, forming 120-nm-diameter basketlike structures. In digitonin-permeabilized resting parietal cells, the intracellular distribution of immunofluorescently labeled clathrin was suggestive of labeling of the tubulovesicular compartment. Clathrin was also unexpectedly localized to canalicular (apical) membranes, as were alpha-adaptin and dynamin, suggesting that this membrane domain of resting parietal cells is endocytotically active. At the ultrastructural level, clathrin was immunolocalized to canalicular and tubulovesicular membranes. H-K-ATPase was immunolocalized to the same membrane domains as clathrin but did not appear to be enriched at the specific subdomains that were enriched in clathrin. Finally, in immunofluorescently labeled primary cultures of parietal cells, in contrast to the H-K-ATPase, intracellular clathrin was found not to translocate to the apical membrane on secretagogue stimulation. Taken together, these biochemical and morphological data provide a framework for characterizing the role of clathrin in the regulation of membrane trafficking from tubulovesicles and at the canalicular membrane in parietal cells.

Clathrin in mitotic spindles.

Subconfluent cultures of Madin-Darby canine kidney (MDCK) and CV-1 cells were immunostained with two monoclonal antibodies (MAbs), MAb X-22 and MAb 23, against clathrin heavy chain and with polyclonal antiserum against a conserved region of all mammalian clathrin light chains. In interphase MDCK and CV-1 cells, staining by all three antibodies resulted in the characteristic intracellular punctate vesicular and perinuclear staining pattern. In mitotic cells, all three anti-clathrin antibodies strongly stained the mitotic spindle. Staining of clathrin in the mitotic spindle was colocalized with anti-tubulin staining of microtubular arrays in the spindle. Staining of the mitotic spindle was evident in mitotic cells from prometaphase to telophase and in spindles in mitotic cells released from a thymidine-nocodazole block. In CV-1 cells, staining of clathrin in the mitotic spindle was not affected by brefeldin A. On Western blots, clathrin was detected, but not enriched, in isolated spindles. The immunodetection of clathrin in the mitotic spindle may suggest a novel role for clathrin in mitosis. Alternatively, the recruitment of clathrin to the spindle may suggest a novel regulatory mechanism for localization of clathrin in mitotic cells.

A tuftelin-interacting protein (TIP39) localizes to the apical secretory pole of mouse ameloblasts.

Enamel biomineralization is a complex process that involves interactions between extracellular matrix proteins. To identify proteins interacting with tuftelin, a potential nucleator of enamel crystallites, the yeast two-hybrid system was applied to a mouse tooth expression library and a tuftelin-interacting protein (TIP) was isolated for further characterization. Polyclonal antibodies were prepared against two recombinant variants of this protein. Both antibodies identified a major protein product in tooth organs at 39 kDa, and this protein has been called TIP39. Northern analysis showed TIP39 messenger RNA in multiple organs, a pattern similar to that of tuftelin messenger RNA. In situ hybridization of mandibles of 1-day-old mice detected TIP39 RNA in secretory ameloblasts and odontoblasts. Immunolocalization of TIP39 and tuftelin in cultured ameloblast-like cells showed that these two proteins colocalize. Within the developing tooth organ, TIP39 and tuftelin immunolocalized to the apical pole of secretory ameloblasts (Tomes' processes) and to the newly secreted extracellular enamel matrix. TIP39 amino acid sequence appears to be highly conserved with similarities to proteins in species as diverse as yeast and primates. Available sequence data and the findings reported here suggest a role for TIP39 in the secretory pathway of extracellular proteins.

Interaction of alpha- and beta-subunits in native H-K-ATPase and cultured cells transfected with H-K-ATPase beta-subunit.

The assembly of the beta-subunit of the gastric H-K-ATPase (HKbeta) with the alpha-subunit of the H-K-ATPase or the Na-K-ATPase (NaKalpha) was characterized with two anti-HKbeta monoclonal antibodies (MAbs). In fixed gastric oxyntic cells, in H-K-ATPase in vitro, and in Madin-Darby canine kidney (MDCK) cells transfected with HKbeta, MAb 2/2E6 was observed to bind to HKbeta only when interactions between alpha- and beta-subunits were disrupted by various denaturants. The epitope for MAb 2/2E6 was mapped to the tetrapeptide S(226)LHY(229) of the extracellular domain of HKbeta. The epitope for MAb 2G11 was mapped to the eight NH(2)-terminal amino acids of the cytoplasmic domain of HKbeta. In transfected MDCK cells, MAb 2G11 could immunoprecipitate HKbeta with alpha-subunits of the endogenous cell surface NaKalpha, as well as that from early in the biosynthetic pathway, whereas MAb 2/2E6 immunoprecipitated only a cohort of unassembled endoglycosidase H-sensitive HKbeta. In HKbeta-transfected LLC-PK(1) cells, significant immunofluorescent labeling of HKbeta at the cell surface could be detected without postfixation denaturation or in live cells, although a fraction of transfected HKbeta could also be coimmunoprecipitated with NaKalpha. Thus assembly of HKbeta with NaKalpha does not appear to be a stringent requirement for cell surface delivery of HKbeta in LLC-PK(1) cells but may be required in MDCK cells. In addition, endogenous posttranslational regulatory mechanisms to prevent hybrid alpha-beta heterodimer assembly appear to be compromised in transfected cultured renal epithelial cells. Finally, the extracellular epitope for assembly-sensitive MAb 2/2E6 may represent a region of HKbeta that is associated with alpha-beta interaction.

MHC class II molecules, cathepsins, and La/SSB proteins in lacrimal acinar cell endomembranes.

Sjögren's syndrome is a chronic autoimmune disease affecting the lacrimal glands and other epithelia. It has been suggested that acinar cells of the lacrimal glands provoke local autoimmune responses, leading to Sjögren's syndrome when they begin expressing major histocompatibility complex (MHC) class II molecules. We used isopycnic centrifugation and phase partitioning to resolve compartments that participate in traffic between the basolateral membranes and the endomembrane system to test the hypothesis that MHC class II molecules enter compartments that contain potential autoantigens, i.e., La/SSB, and enzymes capable of proteolytically processing autoantigen, i.e., cathepsins B and D. A series of compartments identified as secretory vesicle membranes, prelysosomes, and microdomains of the trans-Golgi network involved in traffic to the basolateral membrane, to the secretory vesicles, and to the prelysosomes were all prominent loci of MHC class II molecules, La/SSB, and cathepsins B and D. These observations support the thesis that lacrimal gland acinar cells that have been induced to express MHC class II molecules function as autoantigen processing and presenting cells.