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PubMedDate not supplied

Mosaic pattern of hepatocellular carcinoma: histologic basis for a characteristic CT appearance.

PURPOSE: The mosaic pattern is a characteristic CT appearance for hepatocellular carcinoma (HCC). This study was designed to assess the tissue composition responsible for the CT mosaic pattern. METHOD: Gross and whole-mount histologic sections of 10 HCC tumors from eight patients were prepared at identical levels as preoperative CT sections. CT features of the mosaic tumor pattern were spatially registered with the corresponding pathologic sections. RESULTS: CT of mosaic HCC demonstrated enhancing nodules (9/10), low attenuation areas (9/10), and internal septa (3/10). Spatial registration of CT and microscopic sections showed that enhancing tissue was viable tumor in nine of nine. Low attenuation areas were either necrotic (4/9) or of mixed tissue (5/9), including areas of necrosis, fibrosis, and hemorrhage. CONCLUSION: The variable tissue composition of HCC accounts for the mosaic CT pattern. In most patients, enhancing nodules indicate viable tumor cells, and low attenuation areas represent necrosis, fibrosis, or hemorrhage.

Aged↗
PubMed2005

Generalized mosaicing: polarization panorama.

We present an approach to image the polarization state of object points in a wide field of view, while enhancing the radiometric dynamic range of maging systems by generalizing image mosaicing. The approach is biologically-inspired, as it emulates spatially varying polarization sensitivity of some animals. In our method, a spatially varying polarization and attenuation filter is rigidly attached to a camera. As the system moves, it senses each scene point multiple times, each time filtering it through a different filter polarizing angle, polarizance, and transmittance. Polarization is an additional dimension of the generalized mosaicing paradigm, which has recently yielded high dynamic range images and multispectral images in a wide field of view using other kinds of filters. The image acquisition is as easy as in traditional image mosaics. The computational algorithm can easily handle nonideal polarization filters (partial polarizers), variable exposures, and saturation in a single framework. The resulting mosaic represents the polarization state at each scene point. Using data acquired by this method, we demonstrate attenuation and enhancement of specular reflections and semireflection separation in an image mosaic.

Algorithms↗
PubMed2003

Novel charge-mosaic membranes.

Novel charge-mosaic composite membranes composed of cation and anion permeable domains were prepared. Poly(4-methylstyrene-isoprene-styrene-isoprene-4-methylstyrene) pentablock copolymer (MsISIMs), poly(isoprene-4-methylstyrene) diblock copolymer (IMs), and poly(isoprene-styrene-isoprene) triblock copolymer (ISI), used as the precursor of the charge-mosaic membranes, were polymerized from styrene (S), isoprene (I), and 4-methylstyrene (Ms). MsISIMs and a blend of ISI and IMs were then dissolved in benzene and cast on a polypropylene microporous supporting membrane. After chemical modification, the MsISIMs and IMs/ISI charge-mosaic composite membranes were obtained. Our experimental results show that the IMs/ISI charge-mosaic composite membrane is similar in membrane structure and properties to the MsISIMs charge-mosaic composite membrane.

Electrochemistry↗
PubMed2006

Amino acid substitutions in mosaic penicillin-binding protein 2 associated with reduced susceptibility to cefixime in clinical isolates of Neisseria gonorrhoeae.

The molecular mechanisms of reduced susceptibility to cefixime in clinical isolates of Neisseria gonorrhoeae, particularly amino acid substitutions in mosaic penicillin-binding protein 2 (PBP2), were examined. The complete sequence of ponA, penA, and por genes, encoding, respectively, PBP1, PBP2, and porin, were determined for 58 strains isolated in 2002 from Japan. Replacement of leucine 421 by proline in PBP1 and the mosaic-like structure of PBP2 were detected in 48 strains (82.8%) and 28 strains (48.3%), respectively. The presence of mosaic PBP2 was the main cause of the elevated cefixime MIC (4- to 64-fold). In order to identify the mutations responsible for the reduced susceptibility to cefixime in isolates with mosaic PBP2, penA genes with various mutations were transferred to a susceptible strain by genetic transformation. The susceptibility of partial recombinants and site-directed mutants revealed that the replacement of glycine 545 by serine (G545S) was the primary mutation, which led to a two- to fourfold increase in resistance to cephems. Replacement of isoleucine 312 by methionine (I312M) and valine 316 by threonine (V316T), in the presence of the G545S mutation, reduced susceptibility to cefixime, ceftibuten, and cefpodoxime by an additional fourfold. Therefore, three mutations (G545S, I312M, and V316T) in mosaic PBP2 were identified as the amino acid substitutions responsible for reduced susceptibility to cefixime in N. gonorrhoeae.

Amino Acid Sequence↗
PubMed2003

Sexual mosaics induced by tetracycline treatment in the Wolbachia-infected adzuki bean borer, Ostrinia scapulalis.

Wolbachia-infected Ostrinia scapulalis (Lepidoptera: Crambidae) females generate all-female or nearly all-female broods. Curing the infection by tetracycline treatment during larval stages results in the generation of all-male broods in the next generation. Here we show that sexually mosaic offspring are produced by Wolbachia-infected females treated with tetracycline at the adult stage. The sexual mosaics had wings that were composed of distinctive female and male sectors. Besides wings, the sexually dimorphic mid tibiae displayed an intermediate morphology in some of the mosaics. Many of the mosaic individuals had an abnormal structure of the external genitalia as well, a combination of the male uncus and the female ovipositor. We assume that Wolbachia has a feminizing effect on O. scapulalis genetic males and, hence, incomplete curing of the Wolbachia infection results in the generation of sexually mosaic individuals.

Animals↗
PubMed1986

Gardnerella vaginalis and mosaic colposcopic pattern of the cervix: casual or causal association?

We made a retrospective study of the flora found in the vaginal smears of sexually active women who presented with a mosaic colposcopic pattern of the uterine cervix in an attempt to study some of its epidemiologic factors. Of the 195 cervicovaginal cytologies of patients with mosaic, 61 revealed an abnormal flora (31.2%) while of the 9,856 patients without mosaic, only 2,234 cytologies had an abnormal flora (22.7%) demonstrating a statistically significant higher frequency (p less than 0.0001) of an abnormal flora in women with a mosaic pattern on the cervix. A statistically significant association (p less than 0.02) was encountered between the presence of Gardnerella vaginalis and the mosaic colposcopic pattern, and surprisingly a statistically greater frequency (p less than 0.05) of biopsied dysplasias in the same group. At the moment we can interpret these observations as nothing more than interesting initial findings.

Adult↗
PubMed2001

Gradient model versus mosaic model of the sinoatrial node.

BACKGROUND: A radical reinterpretation (mosaic model) of the makeup of the sinoatrial (SA) node has been proposed to explain the characteristic regional differences in electrical activity between the periphery and center of the SA node. According to the mosaic model, the differences result from a change in the mix of atrial cells and uniform SA node cells from periphery to center, whereas according to the alternative gradient model, there are no atrial cells within the functional SA node, and the differences result from a change in the intrinsic properties of SA node cells from periphery to center. METHODS AND RESULTS: A mosaic model of peripheral and central tissue has been constructed computationally by use of a coupled ordinary differential equation network (CODE) in a 2D lattice (20x20), with each node of the lattice designated randomly as an atrial cell or SA node cell (in correct proportions for periphery and center). The mosaic model fails to predict the characteristic differences in action potential rate and shape between the periphery and center, whereas the existing gradient model can do so. CONCLUSIONS: The mosaic model of the SA node is untenable, and the SA node is adequately described by the gradient model.

Animals↗
PubMed2004

A moving wave patterns the cone photoreceptor mosaic array in the zebrafish retina.

In this paper, we describe the embryonic origin and patterning of the planar mosaic array of cone photoreceptor spectral subtypes in the zebrafish retina. A discussion of possible molecular mechanisms that might generate the cone mosaic array considers but discards a model that accounts for formation of neuronal mosaics in the inner retina and discusses limitations of mathematical simulations that reproduce the zebrafish cone mosaic pattern. The formation and organization of photoreceptors in the ommatidia of the compound eye of Drosophila is compared with similar features in the developing zebrafish cone mosaic, and a model is proposed that invokes spatiotemporally coordinated cell-cell interactions among cone progenitors to determine the identity and positioning of cone spectral subtypes.

Animals↗
PubMed2003

Development of the cone photoreceptor mosaic in the mouse retina revealed by fluorescent cones in transgenic mice.

PURPOSE: Normal function of the retina relies on the orderly stereotyped organization of different neurons and their synaptic connections. How such neural organization is patterned during development remains poorly understood due to the paucity of adequate developmental markers. This study was to examine the spatial organization and development of cone photoreceptors quantitatively in the mouse retina. METHODS: A transgenic approach was used to generate a living cone cell marker by driving GFP expression in mouse cones with the human red/green opsin gene 5' sequences. The spatial organization and development of the cones in the mouse retinas were examined quantitatively with epifluorescence and scanning laser confocal microscopy. Cone specific GFP expression in the developing retinas was verified with peanut agglutinin (PNA) staining. Developmental expression of mouse cone opsin genes was determined with RT-PCR. RESULTS: The fluorescent retinal cells expressing GFP can be visualized as early as on embryonic day E15. Following up morphological differentiation of these cells revealed features that were consistent with the typical morphology of the mouse cones. Double labeling with cone specific PNA showed that these cells were co-labeled starting from postnatal day P1, and that a subpopulation of PNA positive cones expressed the GFP. The fluorescent cell densities had a similar ventral and dorsal distribution from E15 to P2, increased dramatically in the ventral by P6, and in the dorsal from P7. Nearest neighbor distance analysis demonstrated that this subpopulation of cones was organized into a regular mosaic pattern with a regularity index of 4.82 in the central and 3.55 in the peripheral retina. Quantitative pattern assessment of the developing cones revealed that the fluorescent cells appeared to be distributed in a non-random array before birth. The regularity of the cone array began to rise on P7, in parallel with the onset of mouse green opsin gene expression and the development of cone pedicles. The regular pattern of cone mosaic organization was basically formed by P10, coinciding with the timing of the cone pedicle maturation. CONCLUSIONS: The cones in the mouse retina are organized in a regular mosaic pattern. Patterning the cone mosaic appears to follow a two phase developmental process involving regulated opsin gene expression and cone pedicle maturation: an early phase where a non-random array emerges during cone differentiation, and a late phase where the regular mosaic pattern is mature at the time when cone synaptic contacts are being formed.

Animals↗
PubMedDate not supplied

Impaired somatostatin accumulation within the median eminence in mice with mosaic mutation.

OBJECTIVES: The mosaic mutation (Atp7a(mo-ms)) linked to X-chromosome is caused by changes in the Atp7a gene encoding CPx-type protein responsible for the ATP-dependent copper transport across cell membranes. Mosaic mutant males represent an animal model for Menkes disease in humans. Starting from the eighth day of life the mosaic males exhibit a progressive decrease in body weight with poor viability and progressive paresis of the hind limbs. In order to examine whether hypothalamic somatostatin metabolism may be different in normal and copper deficient mice, somatostatin accumulation at the level of median eminence in 14 days old normal and mosaic mutant males was compared. METHODS: An electron microscopic immunocytochemical study on ultrathin brain slices was performed according to post-embedding immunogold procedure. RESULTS: In non-mutant animals somatostatin has been detected in many synapses within median eminence. Gold particles moderately decorated synaptic vesicles and mitochondria. In mosaic mutant animals somatostatin expression within the median eminence was very low and only a few gold particles represented somatostatin. Particles were sporadically associated with synaptic vesicles, mitochondria or cytoskeleton elements. Moreover, pre- and post- synaptic parts of synapses were very often swollen. CONCLUSION: Our data demonstrating that copper deficiency leads to the pathological changes within the median eminence ultrastructure and severe impairment of somatostatin expression suggest that this trace metal is an important element necessary for normal neurohormonal brain development.

Adenosine Triphosphatases↗
PubMed1994

Immunosorbent electron microscopic studies on a tobamovirus causing brinjal necrotic mosaic.

Serological relationships of brinjal necrotic mosaic virus (BNMV), a strain of tobacco mosaic virus (TMV) causing necrotic mosaic disease of brinjal in India to other TMV strains was investigated by immunosorbent electron microscopy (ISEM). The intensity of trapping and decoration revealed a close relationship of BNMV to TMV-D, TMV-U1 and TMV-WU1 strains, and a distant relationship to TMV-A1 and TMV-P11 strains. There was a negligible relationship to TMV-P14, tomato mosaic virus (ToMV) and cucumber green mottle mosaic virus (CGMMV). Therefore, BNMV is proposed to be distinct from the previously reported TMV-A1 strain of brinjal.

India↗
PubMed1996

Temporal expression of rod and cone opsins in embryonic goldfish retina predicts the spatial organization of the cone mosaic.

PURPOSE: Cone photoreceptors in teleost fish retina are organized into a precise, crystalline mosaic in which the four spectral subtypes have a consistent position relative to each other. The objective of the current study was to describe the spatial and temporal progression of photoreceptor differentiation in the embryonic goldfish retina to understand how the retinal cone mosaic might be produced. METHODS: To identify developing photoreceptors when they first begin to express a specific opsin, the authors used in situ hybridization with cRNA probes generated from cDNA for rod opsin and red, green, blue, and ultraviolet cone opsins from goldfish (Carassius auratus). RESULTS: In the retina, rod opsin was expressed first, and it was restricted to a small patch of regularly spaced, precocious rods located near the ventronasal edge of the retina, close to the choroid fissure. The patch enlarged by recruitment of additional rods in a circular path, moving from ventral to nasal to dorsal to temporal retina. Expression of cone opsins began approximately 10 hours after rod opsin was first expressed, and differentiation of cone photoreceptors followed the spatial pattern laid down by the early rods. The temporal order of onset of cone opsin expression was red, then green, then blue, then ultraviolet. When rod and red cone opsin probes were combined, the number of labeled cells was additive, suggesting that these two opsins are expressed in separate populations of photoreceptors. CONCLUSIONS: The onset of opsin expression in goldfish retina follows a highly ordered spatio-temporal pattern. Early differentiation and regular spacing of the precocious rods was unexpected and suggested that they may play a role in cone mosaic patterning. The order of subsequent cone opsin expression was related to the relative positions of cone subtype in the mosaic, suggesting the possibility that inductive interactions among developing photoreceptors may be responsible for patterning the cone mosaic array.

Animals↗
PubMed2026

Costello Syndrome Associated With Somatic Mosaicism of Rare p.Gly13Asp HRAS Variant: Expanding the Phenotypic Spectrum.

BACKGROUND: Costello syndrome (CS) is a rare RASopathy, mostly caused by de novo heterozygous pathogenic variants in the HRAS gene. Over 80% of cases involve the germline p.Gly12Ser variant, resulting in a fairly uniform phenotype of neuro-cardio-facio-cutaneous involvement with an increased risk of malignancy. Consequences of other rare HRAS variants are less well understood due to the limited number of reported cases. METHODS: An adult, young woman was referred due to sparse, slow-growing scalp hair, Blaschko-linear hyperpigmentation, acanthosis nigricans, palmoplantar hyperkeratosis, and joint hyperlaxity. Molecular, imaging, and detailed laboratory studies were performed. RESULTS: Although initial clinical exome- and whole-exome sequencing (WES) were inconclusive, indicating possible mosaicism, subsequent WES from hair-derived DNA samples revealed somatic mosaicism for the rare HRAS p.Gly13Asp variant. Brain MRIs showed a cerebral cavernoma, while cardiological evaluation, urinalysis, abdominal, and pelvic ultrasound were unremarkable. Nevertheless, she remains under close follow-up. CONCLUSION: Among the ten reported individuals carrying the p.Gly13Asp variant, our patient is only the second with confirmed mosaicism and the fifth mosaic CS case described to date. This case expands the phenotypic spectrum of CS and highlights the need for multi-tissue analysis in attenuated or atypical presentations to ensure a correct diagnosis, oncological risk assessment, and informed genetic and reproductive counseling.

Humans↗
PubMed1977

Fluorescent study of tobacco mosaic virus protein.

Protein fluorescence properties of tobacco mosaic virus [3 Trp residues per monomer (positions 17, 52, 152)] and of two tobacco mosaic virus mutants [green tomato atypical mosaic virus, 2 Trp (52, 152) and cucumber virus4, 1 Trp (unknown position)] have been studied. Emission spectra, fluorescence quantum yields and lifetimes were determined. Results showed that protein fluorescence is due to buried Trp only, except for the cucumber virus4 strain, in which Tyr also contributed to the emission. Comparison of the three strains showed that Trp 17 and Trp 52 have high fluorescence yields (phi17 = 0.29; phi52 = 0.37) whereas Trp 152 (probably present in cucumber virus4) is strongly quenched (phi152 = 0.035). An unusually efficient Tyr leads to Trp energy transfer was observed in tobacco mosaic virus protein, indicating that most of four Tyr residues are located near the highly fluorescent Trp.

Mathematics↗
PubMed1984

Nucleotide sequence of cucumber-mosaic-virus RNA 2 reveals a translation product significantly homologous to corresponding proteins of other viruses.

The nucleotide sequence of the 3035 residues of RNA 2 (Mr 1.03 X 10(6) ) of the Q strain of cucumber mosaic virus (CMV) was determined by sequencing M13 clones of the RNA 2 cDNA and by dideoxy sequencing using primers prepared either from M13 clones or by chemical synthesis. A single long open reading frame starts at the second AUG from the 5' end of RNA 2 and encodes 839 amino acids (Mr 94333). This frame has flanking regions of 92 nucleotides at the 5' terminus and 423 nucleotides at the 3' terminus. Computer analysis of the nucleotide sequence showed that CMV RNA 2 has a significant homology with RNA 2 of brome mosaic virus (BMV) and alfalfa mosaic virus (AMV) and also with a region for tobacco mosaic virus (TMV) RNA encoding the read-through part of the 183-kDa protein. About 400 amino acids in the central region of the CMV RNA 2 translation product have a striking homology with the corresponding proteins encoded by BMV and AMV and with the read-through part of the TMV 183-kDa protein. Hydrophobicity plots of CMV and BMV RNA translation products also had apparent similarities. It is concluded that CMV is related to BMV, AMV and TMV in order of increasing evolutionary divergence.

Amino Acid Sequence↗
PubMed1996

Mosaicism for the FMR1 gene influences adaptive skills development in fragile X-affected males.

Fragile X syndrome is one of the most common forms of inherited mental retardation, and the first of a new class of genetic disorders associated with expanded trinucleotide repeats. Previously, we found that about 41% of affected males are mosaic for this mutation in that some of their blood cells have an active fragile X gene and others do not. It has been hypothesized that these mosaic cases should show higher levels of functioning than those who have only the inactive full mutation gene, but previous studies have provided negative or equivocal results. In the present study, the cross-sectional development of communication, self-care, socialization, and motor skills was studied in 46 males with fragile X syndrome under age 20 years as a function of two variables: age and the presence or absence of mosaicism. The rate of adaptive skills development was 2-4 times as great in mosaic cases as in full mutation cases. There was also a trend for cases with autism to be more prevalent in the full-mutation group. These results have implications for prognosis, for the utility of gene or protein replacement therapies for this disorder, and for understanding the association between mental retardation, developmental disorders, and fragile X syndrome.

Adolescent↗
PubMed1996

Mosaicism for del(17)(p11.2p11.2) underlying the Smith-Magenis syndrome.

Smith-Magenis syndrome (SMS) is a multiple congenital anomalies/mental retardation syndrome associated with deletion of band p11.2 of chromosome 17. The deletion is typically detected by high-resolution cytogenetic analysis of chromosomes from peripheral lymphocytes. Fluorescence in situ hybridization (FISH) has been previously used to rule out apparent mosaicism for del(17)(p11.2p11.2) indicated by routine cytogenetics. We now report mosaicism for del(17)(p11.2p11.2) in a child with SMS. The mosaicism had gone undetected during previous routine cytogenetic analysis. FISH analysis of peripheral lymphocytes as well as immortalized lymphoblasts using markers from 17p11.2 revealed that approximately 60% of cells carried the deletion. To our knowledge, this is the first case of SMS associated with mosaicism for del(17)(p11.2p11.2).

Abnormalities, Multiple↗
PubMed1996

Identification of mosaicism in Prader-Willi syndrome using fluorescent in situ hybridization.

We report on our findings of 4 patients with mosaicism for a deletion of chromosome 15, most commonly associated with Prader-Willi syndrome (PWS). We examined a series of typical and atypical PWS patients in order to identify cytogenetically undetected deletions, using fluorescence in situ hybridization. In 4 of the patients analyzed we detected a deletion in 14-60% of peripheral blood leukocytes, using four commercially available probes. Our results indicate that mosaicism may play a role in the etiology of some PWS cases. These findings may be especially useful in patients who display discrepancies between clinical phenotype and established diagnostic criteria. Methylation and microsatellite polymorphism analyses of 2 patients with low-level mosaicism failed to identify the deletion. We propose that fluorescence in situ hybridization is the most effective method for detecting somatic mosaicism, since a large number of cells can be individually examined for the presence or absence of a specific deletion.

Adolescent↗