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PubMed1988

Variations in human corpus callosum do not predict gender: a study using magnetic resonance imaging.

Controversy exists in the neuropsychological literature concerning the existence of gender-associated differences in cognitive functioning and in hemispheric lateralization of cognitive functions. A recent study, based on 14 brains obtained at autopsy, reported sex differences in the splenium of the human corpus callosum and suggested that the larger splenium in females reflects less hemispheric lateralization, or "specialization," than the male brain for visuospatial functions. Our measurements of the human corpus callosum using magnetic resonance images of 37 living subjects failed to confirm reported sex differences in the splenium. A marginally significant sex-related difference in minimum body width and an age-related decrease in anteroposterior distance were found. Most striking were the large variations in callosal size and shape among individuals regardless of age or gender. Existing knowledge of the functions of the corpus callosum does not permit correlations between variations in callosal size and shape and variations in cognitive functions.

Adolescent↗
PubMed1992

Partial callosotomy and left-right response differentiation in the rat: separate anterior and posterior facilitatory effects.

Earlier research demonstrated that complete section of the corpus callosum in the rat reduced the number of trials required to acquire a left-right response differentiation (LRRD). This study was designed to investigate whether the facilitatory effect on LRRD could be produced by section of an anatomical subdivision of the callosum. Rats with sections of the anterior or posterior corpus callosum mastered the LRRD task faster than sham subjects, but more slowly than rats with total callosal section; section of the middle portion of the callosum had no such effect. The partial facilitatory effects of anterior and posterior callosotomy appear to be independent, and suggest that the callosal intermixing of lateral information, which contributes to left-right confusion, occurs at both the sensory and motor levels of processing.

Animals↗
PubMed1997

Individual differences in lateralization: effects of gender and handedness.

Male and female left- and right-handers participated in 3 experiments designed to investigate 3 components of performance asymmetry in lateralized tasks. Experiment 1 used a consonant-vowel-consonant (CVC) identification task measuring quantitative differences in hemispheric abilities and hemispheric control and qualitative differences in hemispheric strategies. The quantitative data revealed that left-handers have a smaller performance asymmetry than do right-handers and that both groups have the same degree of increased accuracy when stimuli are presented bilaterally. Handedness affected the qualitative measures of men, not of women. Experiment 2 used nominal and physical letter-matching tasks with bilateral presentations and measured the flexibility of callosal function. The results suggest that left-handers have less flexible interhemispheric communication than do right-handers and show no effect of gender. Experiment 3 used a chair identification task indexing hemispheric arousal bias. Left-handers tended to have more aroused right than left hemispheres, whereas the distribution of right-handers was centered around 0 arousal bias. Intertask analyses revealed a relationship between arousal bias and metacontrol, where individuals with more aroused right hemispheres tended to use a right-hemisphere strategy in the bilateral condition of the CVC experiment. Intercorrelations between measures from the experiments revealed only a limited relationship between metacontrol patterns in the CVC task and a measure of callosal flexibility in the physical letter-matching task. The results are discussed in the context of the relationships between dimensions of hemispheric asymmetry.

Adult↗
PubMed2001

The Arabidopsis aberrant growth and death2 mutant shows resistance to Pseudomonas syringae and reveals a role for NPR1 in suppressing hypersensitive cell death.

A novel Arabidopsis mutant has been identified with constitutive expression of GST1-GUS using plants with a pathogen-responsive reporter transgene containing the beta-glucuronidase (GUS) coding region driven by the GST1 promoter. The recessive mutant, called agd2 (aberrant growth and death2), has salicylic acid (SA)-dependent increased resistance to virulent and avirulent strains of the bacterial pathogen Pseudomonas syringae, elevated SA levels, a low level of spontaneous cell death, callose deposition, and enlarged cells in leaves. The enhanced resistance of agd2 to virulent P. syringae requires the SA signaling component NONEXPRESSOR OF PR1 (NPR1). However, agd2 renders the resistance response to P. syringae carrying avrRpt2 NPR1-independent. Thus agd2 affects both an SA- and NPR1-dependent general defense pathway and an SA-dependent, NPR1-independent pathway that is active during the recognition of avirulent P. syringae. agd2 plants also fail to show a hypersensitive cell death response (HR) unless NPR1 is removed. This novel function for NPR1 is also apparent in otherwise wild-type plants: npr1 mutants show a stronger HR, while NPR1-overproducing plants show a weaker HR when infected with P. syringae carrying the avrRpm1 gene. Spontaneous cell death in agd2 is partially suppressed by npr1, indicating that NPR1 can suppress or enhance cell death depending on the cellular context. agd2 plants depleted of SA show a dramatic exacerbation of the cell-growth phenotype and increased callose deposition, suggesting a role for SA in regulating growth and this cell-wall modification. AGD2 may function in cell death and/or growth control as well as the defense response, similarly to what has been described in animals for the functions of NFkappaB.

Arabidopsis↗
PubMed2004

Clinical callosum syndrome in a case of multiple sclerosis.

This case report confirms that a clinical callosal disconnection could be observed in multiple sclerosis. Moreover, this case describes a new kind of strange manual behavior related to callosal disconnection. This behavior could neither be considered as a diagonistic dyspraxia nor as an alien hand, but they evoke rather a conflict of intentions.

Adult↗
PubMed1997

Gating of epidermal plasmodesmata is restricted to the leading edge of expanding infection sites of tobacco mosaic virus (TMV).

Plasmodesmatal gating in epidermal cells of Nicotiana tabacum was examined in expanding infection sites of tobacco mosaic virus (TMV) expressing a fusion between the viral movement protein and the green fluorescent protein (MP-GFP). The infection sites were circular in profile and within 3 days post-inoculation had developed a brightly fluorescent leading edge, giving them a characteristic 'halo' shape. Co-localization of MP-GFP with callose demonstrated that nearly all epidermal cell plasmodesmata were targeted with MP-GFP. The fusion protein was located in the centre of the plasmodesmal pore, between paired callose platelets. Increase in plasmodesmatal size exclusion limit, as determined by the passage of microinjected 10 kDa Texas Red dextran, was restricted predominantly to cells within the fluorescent halo, and was virtually absent from cells in the centre of the expanding infection site. The plasmodesmata of these cells, however, remained fluorescently labelled with MP-GFP. Injections outside the fluorescent infection site failed to show movement of dextran, while dextran injected into cells at the leading edge moved inwards towards the centre of the lesion but not outwards into cells lacking GFP. Leaf incisions through cells ahead of the infection front halted the advance of the virus, indicating that virus replication was absent in non-fluorescent cells outside the infection site. The data provide the first demonstration that within an expanding infection site plasmodesmatal gating is under temporal control.

Green Fluorescent Proteins↗
PubMed1999

A male gametophyte-specific monosaccharide transporter in Arabidopsis.

The AtSTP2 gene (sugar transport protein 2) of Arabidopsis thaliana encodes a high affinity, low specificity monosaccharide carrier that can transport a number of hexoses and pentoses at similar rates. AtSTP2 has 12 putative transmembrane helices and a molecular mass of 55.0 kDa. AtSTP2 expression was localized in AtSTP2 promoter-beta-glucuronidase (GUS) Arabidopsis plants showing AtSTP2-driven GUS activity during pollen maturation and also in germinating pollen. Immunohistochemical studies with anti-AtSTP2 antiserum as well as RNA in situ hybridization analyses modified these results and showed that AtSTP2 expression is confined to the early stages of gametophyte development. Both AtSTP2 mRNA and AtSTP2 protein are first seen at the time of beginning callose degradation and microspore release from the tetrades. AtSTP2 mRNA and AtSTP2 protein are no longer detected after the mitotic divisions and the formation of the trinucleate gametophyte. No AtSTP2 mRNA or AtSTP2 protein is seen in fully developed or germinating pollen. The putative role of AtSTP2 in the uptake of glucose units resulting from callose degradation during pollen maturation is discussed.

Amino Acid Sequence↗
PubMed2001

Local expression of enzymatically active class I beta-1, 3-glucanase enhances symptoms of TMV infection in tobacco.

Mutant tobacco plants deficient for class I beta-1,3-glucanase (GLU I) are decreased in their susceptibility to virus infection. This is correlated with delayed virus spread, a reduction in the size exclusion limit of plasmodesmata and increased cell-wall deposition of the beta-1,3-glucan callose. To further investigate a role of GLU I during cell-to-cell movement of virus infection, we inserted the GLU I coding sequence into TMV for overexpression in infected cells. Compared with the size of local lesions produced on plants infected with virus expressing either an enzymatically inactive GLU I or a frameshift mutant of the gene, the size of local lesions caused by infection with virus expressing active GLU I was consistently increased. Viruses expressing antisense GLU I constructs led to lesions of decreased size. Similar effects were obtained for virus spread using plants grown at 32 degrees C to block the hypersensitive response. Together, these results indicate that enzymatically active GLU I expressed in cells containing replicating virus can increase cell-to-cell movement of virus. This supports the view that GLU I induced locally during infection helps to promote cell-to-cell movement of virus by hydrolyzing callose. Moreover, our results provide the first direct evidence that a biological function of a plant beta-1,3-glucanase depends on its catalytic activity.

Biological Transport↗
PubMed2001

Striated palmoplantar keratoderma of Brunauer-Fohs-Siemens.

A 67-year-old African American man presented with callosities of his hands (which he had since adolescence) that were exacerbated by manual labor. His father suffered severe callosities of his feet, but no other family member was afflicted. Physical examination revealed symmetrically distributed linear hyperkeratotic plaques on the palms extending onto the full length of the volar aspect of his digits (Fig. 1). There was no personal or family history of hair, nail, or dental abnormalities. Histologic evaluation showed marked acanthosis, hypergranulosis, and hyperkeratosis of the lesions (Fig. 2). There was no evidence of epidermolytic hyperkeratosis.

Aged↗
PubMed2000

Corpus callosum and cerebral laterality in a modular brain model.

This paper elaborates the function of corpus callosum in the brain model that contains encoding and modulating axons: the former encode data as presynaptic axonal 'on-off' patterns, and the latter help the former convert data into long-term memory through the development of long-term potentiation and depression. It is hypothesized that callosal axons transfer data codes as interhemispheric memory. Bisection of corpus callosum cuts off interhemispheric data transfer and results in strange-hand syndrome, decreased attention and difficulties in acquiring new interdependent bimanual skills. While uniting two hemispheres for a unitary consciousness, corpus callosum contributes to two similar sets of integrated abstract memory, one in each hemisphere. Therefore, it takes bilateral cerebral lesions to manifest a failure of converting short-term memory into long-term memory. The asymmetric callosal data transfer may correlate with cerebral laterality where a cerebral function, such as language, is conducted mainly in one hemisphere for the benefit of less interhemispheric data-traffic. Complete lateralization of a cerebral function is the rare occasion when the specialized neuron groups (modules) for that function all reside in one hemisphere. It is possible that many cerebral functions including language are incompletely lateralized, and corpus callosum links the non-lateralized modules with the lateralized ones. The more the cerebral lateralization, the fewer the non-lateralized modules to be linked, and the smaller the corpus callosum.

Corpus Callosum↗
PubMed2001

Long-term MRI observations of childhood-onset relapsing-remitting multiple sclerosis.

PURPOSE: Long-term MRI follow-up of childhood-onset relapsing-remitting multiple sclerosis (RRMS) was carried out in 4 cases. MRI findings were correlated with clinical course and characteristic differences from adult-onset RRMS were elaborated. METHODS: Two girls and one boy with true childhood-onset, and one girl with juvenile-onset RRMS underwent 5-16 MRI examinations within 6-8 years. The total number of lesions, the numbers of new, active, disappearing and reappearing lesions, infratentorial and U-fibre lesions, "giant" plaques and "black holes" were counted. Callosal atrophy and general brain atrophy were assessed. The findings were related to the physical status according to the Expanded Disability Status Scale (EDSS). RESULTS AND CONCLUSIONS: Results showed that the primary differences in childhood-onset RRMS compared to adult-onset RRMS lie in the lack of, or slower development of irreversible changes ("black hole" formation, brain atrophy). Despite callosal atrophy and intensive U-fibre region involvement, school performance was unchanged. Regarding the frequency of "giant" lesions, an even more pronounced white matter involvement was found in our children compared to adults. All children exhibited a rather "benign" disease course. A more intensive remyelination, less severe neuronal loss, and higher functional brain plasticity at younger ages may account for these differences.

Atrophy↗
PubMedDate not supplied

[Surgical treatment of cavovarus foot deformity considering dynamic pedobarography].

AIM: The operative management of cavovarus foot deformity using soft tissue and bony procedures turns out to be difficult. The present study was undertaken to evaluate an individualised operative treatment and changes in pathologic peak pressure pattern. METHOD: 38 patients (average age 29.6 years, follow-up 44.6 months) with 59 operated feet were examined pre- and postoperatively. The clinical assessment included a questionnaire, ankle ROM and evidence of callosities. Correction of the longitudinal arch was measured on lateral X-rays using Hibbs', calcaneal pitch and Meary's angles. Plantar peak pressures were analysed in 16 patients (21 feet) using dynamic pedobarography (EMED SF4 system). RESULTS: A good subjective functional and cosmetic result were achieved in 74.6 % of the feet. Walking distance, shoe wear and ankle ROM were improved. The height of longitudinal arch and calcaneal dorsiflexion decreased significantly (p = 0.001). An elevated first ray (overcorrection) was noted in 49.1 % of the cases. Postoperative plantar callosities occurred essentially under the lateral border of the foot but were improved compared to the preoperative situation. Dynamic pedobarography showed a significant postoperative (p = 0.002) decrease of loading under the lateral border, but peak pressures remained relatively high in the midfoot area. An increase of peak pressure under the great toe showed a functional improvement at push off. CONCLUSION: The individualised operative concept has proved to be successful and leads to satisfaction with early improvement of foot function and shoe wear. Nevertheless it is difficult to restore muscular balance and normal foot posture in progressive neuromuscular disorders. A more selective use of the Jones procedure, an additional peroneus longus to peroneus brevis tendon transfer and a dorsal wedge extension osteotomy should prevent overcorrection of the first ray. To avoid a relapsed hindfoot varus deformity, a stabilising triple arthrodesis including lateral wedge resection should be performed early in severe deformities.

Adolescent↗
PubMed2004

A family of conserved bacterial effectors inhibits salicylic acid-mediated basal immunity and promotes disease necrosis in plants.

Salicylic acid (SA)-mediated host immunity plays a central role in combating microbial pathogens in plants. Inactivation of SA-mediated immunity, therefore, would be a critical step in the evolution of a successful plant pathogen. It is known that mutations in conserved effector loci (CEL) in the plant pathogens Pseudomonas syringae (the Delta CEL mutation), Erwinia amylovora (the dspA/E mutation), and Pantoea stewartii subsp. stewartii (the wtsE mutation) exert particularly strong negative effects on bacterial virulence in their host plants by unknown mechanisms. We found that the loss of virulence in Delta CEL and dspA/E mutants was linked to their inability to suppress cell wall-based defenses and to cause normal disease necrosis in Arabidopsis and apple host plants. The Delta CEL mutant activated SA-dependent callose deposition in wild-type Arabidopsis but failed to elicit high levels of callose-associated defense in Arabidopsis plants blocked in SA accumulation or synthesis. This mutant also multiplied more aggressively in SA-deficient plants than in wild-type plants. The hopPtoM and avrE genes in the CEL of P. syringae were found to encode suppressors of this SA-dependent basal defense. The widespread conservation of the HopPtoM and AvrE families of effectors in various bacteria suggests that suppression of SA-dependent basal immunity and promotion of host cell death are important virulence strategies for bacterial infection of plants.

Arabidopsis↗
PubMed2001

Arabidopsis cyt1 mutants are deficient in a mannose-1-phosphate guanylyltransferase and point to a requirement of N-linked glycosylation for cellulose biosynthesis.

Arabidopsis cyt1 mutants have a complex phenotype indicative of a severe defect in cell wall biogenesis. Mutant embryos arrest as wide, heart-shaped structures characterized by ectopic accumulation of callose and the occurrence of incomplete cell walls. Texture and thickness of the cell walls are irregular, and unesterified pectins show an abnormally diffuse distribution. To determine the molecular basis of these defects, we have cloned the CYT1 gene by a map-based approach and found that it encodes mannose-1-phosphate guanylyltransferase. A weak mutation in the same gene, called vtc1, has previously been identified on the basis of ozone sensitivity due to reduced levels of ascorbic acid. Mutant cyt1 embryos are deficient in N-glycosylation and have an altered composition of cell wall polysaccharides. Most notably, they show a 5-fold decrease in cellulose content. Characteristic aspects of the cyt1 phenotype, including radial swelling and accumulation of callose, can be mimicked with the inhibitor of N-glycosylation, tunicamycin. Our results suggest that N-glycosylation is required for cellulose biosynthesis and that a deficiency in this process can account for most phenotypic features of cyt1 embryos.

Amino Acid Sequence↗
PubMed2002

In vitro versus in vivo cellulose microfibrils from plant primary wall synthases: structural differences.

Detergent extracts of microsomal fractions from suspension cultured cells of Rubus fruticosus (blackberry) were tested for their ability to synthesize in vitro sizable quantities of cellulose from UDP-glucose. Both Brij 58 and taurocholate were effective and yielded a substantial percentage of cellulose microfibrils together with (1-->3)-beta-d-glucan (callose). The taurocholate extracts, which did not require the addition of Mg(2+), were the most efficient, yielding roughly 20% of cellulose. This cellulose was characterized after callose removal by methylation analysis, electron microscopy, and electron and x-ray synchrotron diffractions; its resistance toward the acid Updegraff reagent was also evaluated. The cellulose microfibrils synthesized in vitro had the same diameter as the endogenous microfibrils isolated from primary cell walls. Both polymers diffracted as cellulose IV(I), a disorganized form of cellulose I. Besides these similarities, the in vitro microfibrils had a higher perfection and crystallinity as well as a better resistance toward the Updegraff reagent. These differences can be attributed to the mode of synthesis of the in vitro microfibrils that are able to grow independently in a neighbor-free environment, as opposed to the cellulose in the parent cell walls where new microfibrils have to interweave with the already laid polymers, with the result of a number of structural defects.

Bacteria↗
PubMed2000

MRI analysis of brain atrophy after severe closed-head injury: relation to clinical status.

The purpose of this study was to determine the clinical correlates of supratentorial ventricular dilations and of corpus callosal atrophy at the subacute stage after a severe closed-head injury (CHI). Thirty-three CHI patients underwent MRI 2 months or more after injury. Morphometric measures were compared to clinical data (coma score, coma duration and Glasgow Outcome Scale). There were numerous significant correlations between clinical data and mid-third ventricle and frontal horns measurements. Fewer significant correlations were found with the lateral ventricle bodies and the corpus callosal body. There was no significant correlation with the posterior part of the corpus callosum and of the ventricles. Corpus callosum atrophy correlated significantly with anterior and deep ventricular dilatation. In conclusion, the best indicator of clinical status was ventriculomegaly, and particularly third ventricle enlargement, which probably reflects the extent of both anterior and deep white matter lesions.

Adult↗
PubMed1968

P protein in the phloem of Cucurbita. II. The P protein of mature sieve elements.

During maturation of sieve elements in Cucurbita maxima Duchesne, the P-protein bodies (slime bodies) usually disperse in the tonoplast-free cell. In some sieve elements the P-protein bodies fail to disperse. The occurrence of dispersal or nondispersal of P-protein bodies can be related to the position of the sieve elements in the stem or petiole. In the sieve elements within the vascular bundle the bodies normally disperse; in the extrafascicular sieve elements the bodies often fail to disperse. Extrafascicular sieve elements showing partial dispersal also occur. The appearance of the sieve plate in fixed material is related to the degree of dispersal or nondispersal of the P-protein bodies. In sieve elements in which complete dispersal occurs the sieve plate usually has a substantial deposit of callose, and the sieve-plate pores are filled with P protein. In sieve elements containing nondispersing P-protein bodies the sieve plate bears little or no callose, and its pores usually are essentially "open." The dispersed P-protein components may aggregate into loosely organized "strands," which sometimes extend vertically through the cell and continue through the sieve-plate pores; but they may be oriented otherwise in the cell, even transversely.

Histocytochemistry↗
PubMed1999

Localization of Cell Wall Polysaccharides during Kiwifruit (Actinidia deliciosa) Ripening.

The localization of pectin, cellulose, xyloglucan, and callose was compared in kiwifruit (Actinidia deliciosa [A. Chev.] C. F. Liang and A. R. Ferguson var. deliciosa "Hayward") at harvest, at the end of the first phase of softening, and when ripe. Pectin was visualized using three different methods: labeling of galacturonic acid residues, labeling of negatively charged groups, and labeling with JIM 5 (nonesterified residues) and JIM 7 (methyl-esterified) monoclonal antibodies. Labeling of pectin gave different results depending on the detection system used. Differences related to patterns of change during ripening and to spatial distribution of label intensity. Cell wall pectin was available for labeling at all stages of fruit softening, but no clear differentiation of the middle lamella region was seen, although JIM 5 binding predominated where the middle lamellae joined the intercellular spaces in unripe fruit. Negatively charged groups (cationic gold labeling) and, to a lesser extent, galacturonic acid residues (Aplysia depilans gonad lectin labeling) were preferentially located near the cell wall/plasma membrane boundary. The lack of strong binding of the JIM antibodies indicated that the reactive groups were inaccessible. Cellulose remained intact and labeled densely across the wall at all stages of fruit ripening. Distribution of xyloglucan was patchy at harvest but was scattered throughout the wall later in ripening. Alterations to labeling of xyloglucan indicated that some epitopes were differentially exposed. Plasmodesmatal regions were clearly different in composition to other wall areas, showing an absence of cellulose labeling, specific pectin labeling, and callose presence. A similar predominance of pectin labeling compared with cellulose also occurred at the middle lamella wedge near intercellular spaces.

Journal Article↗