Registration accuracy for VBM studies varies according to region and degenerative disease grouping

Voxel-based morphometry studies are frequently cited as having the advantage of being objective compared to region-of-interest methods. This statement assumes, however, that all regions are treated equally both in controls and diseased cohorts. This study aimed to test whether this statement is correct by analyzing fiducial landmarks in controls, Alzheimer's disease (as a model of mild generalized atrophy model); Frontotemporal Dementia (focal atrophy model) and Semantic Dementia (extreme focal atrophy model). Standard SPM5 and DARTEL were evaluated using either raw or skull-stripped/bias corrected scans. The results indicated that with all methods there was variability in the degree of misregistration across regions and that there was a disease grouping interaction-most severely in the extreme focal atrophy model (Semantic Dementia). Preprocessing improved VBM outputs both with standard SPM and DARTEL. In the latter case, this occurred to an extreme degree-DARTEL using raw data was grossly insensitive to a ground truth (manually verified hippocampal atrophy in AD) whereas DARTEL after preprocessing yielded excellent results with respect to this yardstick.

LRRTM1 on chromosome 2p12 is a maternally suppressed gene that is associated paternally with handedness and schizophrenia

Left-right asymmetrical brain function underlies much of human cognition, behavior and emotion. Abnormalities of cerebral asymmetry are associated with schizophrenia and other neuropsychiatric disorders. The molecular, developmental and evolutionary origins of human brain asymmetry are unknown. We found significant association of a haplotype upstream of the gene LRRTM1 (Leucine-rich repeat transmembrane neuronal 1) with a quantitative measure of human handedness in a set of dyslexic siblings, when the haplotype was inherited paternally (P=0.00002). While we were unable to find this effect in an epidemiological set of twin-based sibships, we did find that the same haplotype is overtransmitted paternally to individuals with schizophrenia/schizoaffective disorder in a study of 1002 affected families (P=0.0014). We then found direct confirmatory evidence that LRRTM1 is an imprinted gene in humans that shows a variable pattern of maternal downregulation. We also showed that LRRTM1 is expressed during the development of specific forebrain structures, and thus could influence neuronal differentiation and connectivity. This is the first potential genetic influence on human handedness to be identified, and the first putative genetic effect on variability in human brain asymmetry. LRRTM1 is a candidate gene for involvement in several common neurodevelopmental disorders, and may have played a role in human cognitive and behavioral evolution.

A novel autosomal dominant restless legs syndrome locus maps to chromosome 20p13

The authors investigated genetic factors contributing to restless legs syndrome (RLS) by performing a 10-cM genome-wide scan in a large French-Canadian pedigree. They detected an autosomal-dominant locus mapping to chromosome 20p13, with a maximum multipoint lod score of 3.86 at marker D20S849. This is the third reported autosomal-dominant locus for RLS and the first autosomal-dominant RLS locus in the French-Canadian population.

Rice SERK1 gene positively regulates somatic embryogenesis of cultured cell and host defense response against fungal infection

Here we report on the isolation and characterization of a somatic embryogenesis receptor-like kinase (OsSERK1) gene in rice (Oryza sativa). The OsSERK1 gene belongs to a small subfamily of receptor-like kinase genes in rice and shares a highly conserved gene structure and extensive sequence homology with previously reported plant SERK genes. Though it has a basal level of expression in various rice organs/tissues, as high expression level was detected in rice callus during somatic embryogenesis. Suppression of OsSERK1 expression in transgenic calli by RNA interference resulted in a significant reduction of shoot regeneration rate (from 72% to 14% in the japonica rice Zhonghua11). Overexpression of OsSERK1, however, increased the shoot regeneration rate (from 72% to 86%). Interestingly, OsSERK1 is significantly activated by the rice blast fungus, particularly during the incompatible interaction, and is associated with host cell death in Sekigushi lesion mimic mutants. This gene is also inducible by defense signaling molecules such as salicylic acid, jasmonic acid, and abscisic acid. Furthermore, constitutive overexpression of OsSERK1 in two rice cultivars led to an increase in host resistance to the blast fungus. Our data suggest that OsSERK1 may partially mediate defense signal transduction in addition to its basic role in somatic embryogenesis.

Determination of CD30 expression on peripheral blood T lymphocyte subsets in patients with hemorrhagic fever with renal syndrome by FCM

To determine the CD30 expression on peripheral blood T lymphocyte subsets in patients with hemorrhagic fever with renal syndrome (HFRS) and its clinical implications, double immunofluorescence technique and flow cytometry were used. There was no significant difference among the severe group, mild-moderate group and normal control group in the CD4+CD30- T lymphocyte subset. While the CD4+CD30+ T cells of HFRS patients were increased and the difference between severe group and mild-moderate group or normal control group were very significant (P < 0.01) and the difference between the mild-moderate group and normal control group was also significant (P < 0.05). The CD8+CD30- T cells were increased while the CD8+CD30+ T cells decreased obviously in HFRS patients, and the differences among three groups in both subsets were very significant (P < 0.01). The results showed that the humoral immunity and cellular immunity are overactive in HFRS patients during acute phase. The loss of balance between T lymphocyte subsets may play an important role in the pathophysiology of HFRS and is closely correlated with the severity of the HFRS.

Streptomyces sp. 173, an insecticidal micro-organism from marine

AIMS

To find new insecticidal antibiotics from marine micro-organisms.

METHODS AND RESULTS

Strains isolated from seawater and sea sediments from Beidiahe and Dagang of the east coast of China were screened for their insecticidal qualities. The screening was carried out using bioassay of brine shrimp and the insect pest Helicoverpa armigera. The fermentation, preliminary extraction and isolation of Streptomyces sp.173 were carried out.

CONCLUSIONS

In total 331 isolates were examined through bioassay of brine shrimp and 40 isolates (12.08%) showed potential insecticidal activities. Of the 40 isolates, one isolate, designated Streptomyces sp.173, was found to have strong insecticidal activity against both brine shrimp and H. armigera, similar to that of avermectin B1.

SIGNIFICANCE AND IMPACT OF THE STUDY

The isolated Streptomyces sp.173 has great insecticidal potency. This work indicated that marine micro-organisms could be an important source of insecticidal antibiotics and the improved anti-brine shrimp bioassay is suitable for primary screening.

Molecular and genetic aspects of plant responses to osmotic stress

Drought, high salinity and freezing impose osmotic stress on plants. Plants respond to the stress in part by modulating gene expression, which eventually leads to the restoration of cellular homeostasis, detoxification of toxins and recovery of growth. The signal transduction pathways mediating these adaptations can be dissected by combining forward and reverse genetic approaches with molecular, biochemical and physiological studies. Arabidopsis is a useful genetic model system for this purpose and its relatives including the halophyte Thellungiella halophila, can serve as valuable complementary genetic model systems.

CT and MRI characteristics of ossification of the ligamenta flava in the thoracic spine

The purpose of this study was to compare MRI findings with CT findings of mass-forming calcification/ossification of the thoracic ligamenta flava (OTLF). Twenty-one Chinese patients presented with clinical evidence of chronic and progressive thoracic spinal cord compression which included: difficulty in walking; weakness; and/or numbness of the extremities, back pain, and lower extremity paresthesias. Axial and sagittal T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) were performed through the thoracic spine on a 1.0-T Impact unit (Siemens, Erlangen, Germany). Axial CT was obtained with 5-mm contiguous sections through the thoracic region. Decompressive surgery with resection of the OTLF were carried out in all patients. Low signal intensity of the mass-forming OTLF was demonstrated at a single level (n=1) or at multiple levels (n=20) on both T1WI and T2WI. The distribution of OTLF was bilateral at all levels identified in 6 cases, unilateral at all levels in 5 patients, and both unilateral and bilateral at different levels in 10 cases. Ossification of the thoracic ligamenta flava involved the upper thoracic spine (T1-4) in 3 cases, midthoracic spine (T5-8) in 3 cases, lower thoracic spine (T9-12) in 10 cases, and more than one thoracic spinal subregion in 5 cases. Computed tomography confirmed the MR findings regarding the location and distribution of OTLF in all cases, as well as the associated evidence of central spinal canal stenosis. In addition, 5 patients revealed associated ossification of the posterior longitudinal ligament. All patients demonstrated gradual, but incomplete, clinical improvement of the radiculomyelopathy following decompressive surgery. Ossification of the posterior longitudinal ligament resulting in thoracic central spinal canal stenosis and clinical radiculomyelopathy is not uncommon in the Asian people. Ossification of the thoracic ligamenta flava can be accurately evaluated equally well by CT and MR with regard to level(s) and side(s) of involvement, as well as to the relative degree of central spinal canal stenosis and the associated compression of the thoracic spinal cord.

Modulation of abscisic acid signal transduction and biosynthesis by an Sm-like protein in Arabidopsis

The phytohormone abscisic acid (ABA) regulates plant growth and development as well as stress tolerance. The Arabidopsis sad1 (supersensitive to ABA and drought) mutation increases plant sensitivity to drought stress and ABA in seed germination, root growth, and the expression of some stress-responsive genes. sad1 plants are also defective in the positive feedback regulation of ABA biosynthesis genes by ABA and are impaired in drought stress induction of ABA biosynthesis. SAD1 encodes a polypeptide similar to multifunctional Sm-like snRNP proteins that are required for mRNA splicing, export, and degradation. These results suggest a critical role for mRNA metabolism in the control of ABA signaling as well as in the regulation of ABA homeostasis.

Binding site of macrolide antibiotics on the ribosome: new resistance mutation identifies a specific interaction of ketolides with rRNA

Macrolides represent a clinically important class of antibiotics that block protein synthesis by interacting with the large ribosomal subunit. The macrolide binding site is composed primarily of rRNA. However, the mode of interaction of macrolides with rRNA and the exact location of the drug binding site have yet to be described. A new class of macrolide antibiotics, known as ketolides, show improved activity against organisms that have developed resistance to previously used macrolides. The biochemical reasons for increased potency of ketolides remain unknown. Here we describe the first mutation that confers resistance to ketolide antibiotics while leaving cells sensitive to other types of macrolides. A transition of U to C at position 2609 of 23S rRNA rendered E. coli cells resistant to two different types of ketolides, telithromycin and ABT-773, but increased slightly the sensitivity to erythromycin, azithromycin, and a cladinose-containing derivative of telithromycin. Ribosomes isolated from the mutant cells had reduced affinity for ketolides, while their affinity for erythromycin was not diminished. Possible direct interaction of ketolides with position 2609 in 23S rRNA was further confirmed by RNA footprinting. The newly isolated ketolide-resistance mutation, as well as 23S rRNA positions shown previously to be involved in interaction with macrolide antibiotics, have been modeled in the crystallographic structure of the large ribosomal subunit. The location of the macrolide binding site in the nascent peptide exit tunnel at some distance from the peptidyl transferase center agrees with the proposed model of macrolide inhibitory action and explains the dominant nature of macrolide resistance mutations. Spatial separation of the rRNA residues involved in universal contacts with macrolides from those believed to participate in structure-specific interactions with ketolides provides the structural basis for the improved activity of the broader spectrum group of macrolide antibiotics.

pKa of adenine 2451 in the ribosomal peptidyl transferase center remains elusive

The universally conserved A2451 of 23S rRNA has been proposed to participate directly in the catalysis of peptide bond formation in the ribosomal peptidyl transferase center. An unusually high, near neutral, pKa of A2451 is a prerequisite for its action as a general acid-base catalyst. Increased reactivity of A2451 to dimethylsulfate (DMS) at pH 8.5 compared to pH 6.5 was taken as evidence that the pKa of this nucleotide falls within this pH range. Structural data suggested that the interaction between A2451 and G2447 in the ribosome is responsible for A2451 pKa perturbation. In contrast to expectation, our studies did not show pH dependence of A2451 dimethylsulfate modification in ribosomes of Thermus aquaticus and Mycobacterium smegmatis. Other rRNA regions, however, showed major alterations in DMS reactivity at pH 8.5 compared to pH 6.5, suggesting that conformational rearrangements in the structure of the large ribosomal subunit may occur upon the pH shift. The G2447U mutant of M. smegmatis was viable, indicating that the G2447-A2451 interaction is not critical for the ribosome function. We concluded that the proposed unusual pKa of A2451, if existing, may not be crucial for the ribosome activity and that the previously reported pH-dependent alterations in the DMS modification of A2451 do not necessarily reveal an unusual pKa of this nucleotide.

Unverricht-Lundborg disease in a five-generation Arab family: instability of dodecamer repeats

BACKGROUND

Unverricht-Lundborg disease (ULD) is the prototypical form of progressive myoclonus epilepsy, and subjects are usually very photosensitive. ULD is caused by mutations in the cystatin B (CSTB) gene; the most common mutation is expansion of a dodecamer repeat near the promoter. The authors studied a five-generation Arab family with ULD lacking photosensitivity.

METHODS

An Arab family from the Galilee region of Israel with progressive myoclonus epilepsy was clinically evaluated. Blood samples were obtained from three living affected and 16 unaffected individuals. Expansion of dodecamer repeat in the CSTB gene was examined.

RESULTS

The three living affected individuals showed spontaneous and action myoclonus, ataxia, and mild dementia. EEG in two individuals showed generalized polyspike-wave without photosensitivity. The family structure with large sibships and multiple consanguineous loops allowed the authors to examine the gene over four generations of adults. The three living affected individuals were homozygous for repeat expansions and 11 of the 16 unaffected family members were heterozygous. Instability was demonstrated by the presence of expansions of different sizes occurring on the same haplotype background in this inbred family. Fragment size variations could be unequivocally detected in two sibships. The expansions were in the 49 to 54 dodecamer repeat range. Changes in one generation were small, 1 to 4 repeat units, consisting of either enlargements or contractions.

CONCLUSIONS

Instability of the expanded dodecamer repeats in the cystatin B gene is frequent. Almost invariably, a small change is observed in parent-child transmission. The lack of photosensitivity in this family is unexplained.

The Arabidopsis LOS5/ABA3 locus encodes a molybdenum cofactor sulfurase and modulates cold stress- and osmotic stress-responsive gene expression

To understand low temperature and osmotic stress signaling in plants, we isolated and characterized two allelic Arabidopsis mutants, los5-1 and los5-2, which are impaired in gene induction by cold and osmotic stresses. Expression of RD29A-LUC (the firefly luciferase reporter gene under the control of the stress-responsive RD29A promoter) in response to cold and salt/drought is reduced in the los5 mutants, but the response to abscisic acid (ABA) remains unaltered. RNA gel blot analysis indicates that the los5 mutation reduces the induction of several stress-responsive genes by cold and severely diminishes or even completely blocks the induction of RD29A, COR15, COR47, RD22, and P5CS by osmotic stresses. los5 mutant plants are compromised in their tolerance to freezing, salt, or drought stress. los5 plants are ABA deficient, as indicated by increased transpirational water loss and reduced accumulation of ABA under drought stress in the mutant. A comparison with another ABA-deficient mutant, aba1, reveals that the impaired low-temperature gene regulation is specific to the los5 mutation. Genetic tests suggest that los5 is allelic to aba3. Map-based cloning reveals that LOS5/ABA3 encodes a molybdenum cofactor (MoCo) sulfurase. MoCo sulfurase catalyzes the generation of the sulfurylated form of MoCo, a cofactor required by aldehyde oxidase that functions in the last step of ABA biosynthesis in plants. The LOS5/ABA3 gene is expressed ubiquitously in different plant parts, and the expression level increases in response to drought, salt, or ABA treatment. Our results show that LOS5/ABA3 is a key regulator of ABA biosynthesis, stress-responsive gene expression, and stress tolerance.

The Arabidopsis LOS5/ABA3 locus encodes a molybdenum cofactor sulfurase and modulates cold stress- and osmotic stress-responsive gene expression

To understand low temperature and osmotic stress signaling in plants, we isolated and characterized two allelic Arabidopsis mutants, los5-1 and los5-2, which are impaired in gene induction by cold and osmotic stresses. Expression of RD29A-LUC (the firefly luciferase reporter gene under the control of the stress-responsive RD29A promoter) in response to cold and salt/drought is reduced in the los5 mutants, but the response to abscisic acid (ABA) remains unaltered. RNA gel blot analysis indicates that the los5 mutation reduces the induction of several stress-responsive genes by cold and severely diminishes or even completely blocks the induction of RD29A, COR15, COR47, RD22, and P5CS by osmotic stresses. los5 mutant plants are compromised in their tolerance to freezing, salt, or drought stress. los5 plants are ABA deficient, as indicated by increased transpirational water loss and reduced accumulation of ABA under drought stress in the mutant. A comparison with another ABA-deficient mutant, aba1, reveals that the impaired low-temperature gene regulation is specific to the los5 mutation. Genetic tests suggest that los5 is allelic to aba3. Map-based cloning reveals that LOS5/ABA3 encodes a molybdenum cofactor (MoCo) sulfurase. MoCo sulfurase catalyzes the generation of the sulfurylated form of MoCo, a cofactor required by aldehyde oxidase that functions in the last step of ABA biosynthesis in plants. The LOS5/ABA3 gene is expressed ubiquitously in different plant parts, and the expression level increases in response to drought, salt, or ABA treatment. Our results show that LOS5/ABA3 is a key regulator of ABA biosynthesis, stress-responsive gene expression, and stress tolerance.

EmtA, a rRNA methyltransferase conferring high-level evernimicin resistance

Enterococcus faecium strain 9631355 was isolated from animal sources on the basis of its resistance to the growth promotant avilamycin. The strain also exhibited high-level resistance to evernimicin, a drug undergoing evaluation as a therapeutic agent in humans. Ribosomes from strain 9631355 exhibited a dramatic reduction in evernimicin binding, shown by both cell-free translation assays and direct-binding assays. The resistance determinant was cloned from strain 9631355; sequence alignments suggested it was a methyltransferase and therefore it was designated emtA for evernimicin methyltransferase. Evernimicin resistance was transmissible and emtA was localized to a plasmid-borne insertion element. Purified EmtA methylated 50S subunits from an evernimicin-sensitive strain 30-fold more efficiently than those from a resistant strain. Reverse transcription identified a pause site that was unique to the 23S rRNA extracted from resistant ribosomes. The pause corresponded to methylation of residue G2470 (Escherichia coli numbering). RNA footprinting revealed that G2470 is located within the evernimicin-binding site on the ribosome, thus providing an explanation for the reduced binding of the drug to methylated ribosomes.

The Arabidopsis LOS5/ABA3 locus encodes a molybdenum cofactor sulfurase and modulates cold stress- and osmotic stress-responsive gene expression

To understand low temperature and osmotic stress signaling in plants, we isolated and characterized two allelic Arabidopsis mutants, los5-1 and los5-2, which are impaired in gene induction by cold and osmotic stresses. Expression of RD29A-LUC (the firefly luciferase reporter gene under the control of the stress-responsive RD29A promoter) in response to cold and salt/drought is reduced in the los5 mutants, but the response to abscisic acid (ABA) remains unaltered. RNA gel blot analysis indicates that the los5 mutation reduces the induction of several stress-responsive genes by cold and severely diminishes or even completely blocks the induction of RD29A, COR15, COR47, RD22, and P5CS by osmotic stresses. los5 mutant plants are compromised in their tolerance to freezing, salt, or drought stress. los5 plants are ABA deficient, as indicated by increased transpirational water loss and reduced accumulation of ABA under drought stress in the mutant. A comparison with another ABA-deficient mutant, aba1, reveals that the impaired low-temperature gene regulation is specific to the los5 mutation. Genetic tests suggest that los5 is allelic to aba3. Map-based cloning reveals that LOS5/ABA3 encodes a molybdenum cofactor (MoCo) sulfurase. MoCo sulfurase catalyzes the generation of the sulfurylated form of MoCo, a cofactor required by aldehyde oxidase that functions in the last step of ABA biosynthesis in plants. The LOS5/ABA3 gene is expressed ubiquitously in different plant parts, and the expression level increases in response to drought, salt, or ABA treatment. Our results show that LOS5/ABA3 is a key regulator of ABA biosynthesis, stress-responsive gene expression, and stress tolerance.

FIERY1 encoding an inositol polyphosphate 1-phosphatase is a negative regulator of abscisic acid and stress signaling in Arabidopsis

The plant hormone abscisic acid (ABA) plays a wide range of important roles in plant growth and development, including embryogenesis, seed dormancy, root and shoot growth, transpiration, and stress tolerance. ABA and various abiotic stresses also activate the expression of numerous plant genes through undefined signaling pathways. To gain insight into ABA and stress signal transduction, we conducted a genetic screen based on ABA- and stress-inducible gene transcription. Here we report the identification of an Arabidopsis mutation, fiery1 (fry1), which results in super-induction of ABA- and stress-responsive genes. Seed germination and postembryonic development of fry1 are more sensitive to ABA or stress inhibition. The mutant plants are also compromised in tolerance to freezing, drought, and salt stresses. Map-based cloning revealed that FRY1 encodes an inositol polyphosphate 1-phosphatase, which functions in the catabolism of inositol 1, 4, 5-trisphosphate (IP(3)). Upon ABA treatment, fry1 mutant plants accumulated more IP(3) than did the wild-type plants. These results provide the first genetic evidence indicating that phosphoinositols mediate ABA and stress signal transduction in plants and their turnover is critical for attenuating ABA and stress signaling.

FIERY1 encoding an inositol polyphosphate 1-phosphatase is a negative regulator of abscisic acid and stress signaling in Arabidopsis

The plant hormone abscisic acid (ABA) plays a wide range of important roles in plant growth and development, including embryogenesis, seed dormancy, root and shoot growth, transpiration, and stress tolerance. ABA and various abiotic stresses also activate the expression of numerous plant genes through undefined signaling pathways. To gain insight into ABA and stress signal transduction, we conducted a genetic screen based on ABA- and stress-inducible gene transcription. Here we report the identification of an Arabidopsis mutation, fiery1 (fry1), which results in super-induction of ABA- and stress-responsive genes. Seed germination and postembryonic development of fry1 are more sensitive to ABA or stress inhibition. The mutant plants are also compromised in tolerance to freezing, drought, and salt stresses. Map-based cloning revealed that FRY1 encodes an inositol polyphosphate 1-phosphatase, which functions in the catabolism of inositol 1, 4, 5-trisphosphate (IP(3)). Upon ABA treatment, fry1 mutant plants accumulated more IP(3) than did the wild-type plants. These results provide the first genetic evidence indicating that phosphoinositols mediate ABA and stress signal transduction in plants and their turnover is critical for attenuating ABA and stress signaling.

Channel-specific coatings on microfabricated chips

This paper reports channel-specific immobilization of fluorescein-5-isothiocyanate (FITC)-labeled bovine serum albumin and beta-galactosidase on microchips with a central channel and two crossing channels; referred to as a double cross channel configuration. Solvent wells at the termini of all channels were used to store reagents. Coatings were applied in multiple steps using electroosmotically driven flow to deliver reagents to specific channels in the chip. The first step in all coating reactions was derivatization of the capillary walls with an organosilane having a reactive pendant functional group. As the silylating reagent was transported from the reagent storage well to a specific waste well, capillary walls in the route of transport were silylated. Flow was maintained throughout a reaction. The route of transport, and thus the specificity of channel coating, were controlled by the well to which negative potential was applied. Flow in a multichannel network takes the shortest route between the electrodes delivering the motive potential. The second reagent in the reaction was delivered from a different well and took a different path through the channel network, as did other reagents. Only the channel being coated was in the flow path of all the reagents used in the coating process. The zone of immobilization in the case of FITC-labeled albumin was determined with confocal fluorescence microscopy. Enzyme activity of immobilized beta-galactosidase (beta-Gal) was monitored by following the hydrolysis of fluorescein mono-beta-D-galactopyranoside to fluorescein with laser-induced fluorescence.

High field EPR study of the pheophytin anion radical in wild type and D1-E130 mutants of photosystem II in Chlamydomonas reinhardtii

The intermediate electron acceptor in photosystem II is a pheophytin molecule. The radical anion of this molecule was studied using high field electron paramagnetic resonance in a series of Chlamydomonas reinhardtii mutants. Glutamic acid 130 of the D1 polypeptide is thought to hydrogen bond the ring V carbonyl group of this radical. Mutations at this site, designed to weaken or remove this hydrogen bond, strongly affected the g tensor of the radical. The upward shift of the g(x) component followed the decreasing hydrogen bonding capacity of the amino acid introduced. This behavior is similar to that of tyrosyl and semiquinone radicals. It is also consistent with the optical spectra of the pheophytin in similar mutants. Density functional calculations were used to calculate the g tensors and rationalize the observed trend in the variation of the g(x) value for pheophytin and bacteriopheophytin radical. The theoretical results support the experimental observations and demonstrate the sensitivity of g values to the electrostatic protein environment for these types of radicals.

Identification of defense-related rice genes by suppression subtractive hybridization and differential screening

Identification of host genes involved in defense responses is one of most critical steps leading to the elucidation of disease resistance mechanisms in plants. In this study, two different cloning strategies were employed to identify defense-related genes from a tropical japonica rice cultivar (Oryza sativa cv. Drew). With the use of bacterial colony arrays, differential screening of a blast fungus (Pyricularia grisea)-induced rice cDNA library led to the isolation of 22 distinct rice genes that are expressed differentially in response to blast infection. Sequence analysis indicates that most of them are full-length cDNAs encoding pathogenesis-related proteins or other relatively abundant proteins. In combination with treatments of cycloheximide plus jasmonic acid (JA) or benzothiadiazole (BTH) in rice seedlings, the polymerase chain reaction-based suppression subtractive hybridization also was conducted to search for immediate early (IE) defense-related genes whose transcription is independent of de novo protein synthesis. The initial screening of only 768 subtracted clones resulted in the identification of 34 distinct IE genes that are induced by JA, BTH, and/or blast infection. Database searches revealed that these IE genes encode putative mitogen-activated protein kinase, diacylglycerol kinase, zinc finger protein, RelA-SpoT protein, ankyrin-containing protein, ABC transporter, beta-ketoacyl-CoA synthase, and other potential defense-signaling components. Further characterization of these novel IE genes will likely facilitate the elucidation of defense signal transduction in rice plants.

The Arabidopsis HOS1 gene negatively regulates cold signal transduction and encodes a RING finger protein that displays cold-regulated nucleo--cytoplasmic partitioning

Low temperature is one of the most important environmental stimuli that control gene transcription programs and development in plants. In Arabidopsis thaliana, the HOS1 locus is a key negative regulator of low temperature-responsive gene transcription. The recessive hos1 mutation causes enhanced induction of the CBF transcription factors by low temperature as well as of their downstream cold-responsive genes. The hos1 mutant plants flower early, and this correlates with a low level of Flowering Locus C gene expression. The HOS1 gene was isolated through positional cloning. HOS1 encodes a novel protein with a RING finger motif near the amino terminus. HOS1 is ubiquitously expressed in all plant tissues. HOS1--GFP translational fusion studies reveal that HOS1 protein resides in the cytoplasm at normal growth temperatures. However, in response to low temperature treatments, HOS1 accumulates in the nucleus. Ectopic expression of HOS1 in wild-type plants causes cosuppression of HOS1 expression and mimics the hos1 mutant phenotypes.

A novel site of antibiotic action in the ribosome: interaction of evernimicin with the large ribosomal subunit

Evernimicin (Evn), an oligosaccharide antibiotic, interacts with the large ribosomal subunit and inhibits bacterial protein synthesis. RNA probing demonstrated that the drug protects a specific set of nucleotides in the loops of hairpins 89 and 91 of 23S rRNA in bacterial and archaeal ribosomes. Spontaneous Evn-resistant mutants of Halobacterium halobium contained mutations in hairpins 89 and 91 of 23S rRNA. In the ribosome tertiary structure, rRNA residues involved in interaction with the drug form a tight cluster that delineates the drug-binding site. Resistance mutations in the bacterial ribosomal protein L16, which is shown to be homologous to archaeal protein L10e, cluster to the same region as the rRNA mutations. The Evn-binding site overlaps with the binding site of initiation factor 2. Evn inhibits activity of initiation factor 2 in vitro, suggesting that the drug interferes with formation of the 70S initiation complex. The site of Evn binding and its mode of action are distinct from other ribosome-targeted antibiotics. This antibiotic target site can potentially be used for the development of new antibacterial drugs.

Sterile, benign radiculitis associated with lumbosacral lateral recess spinal canal stenosis: evaluation with enhanced magnetic resonance imaging

Two cases of symptomatic lumbar lateral recess stenosis are described in which the compressed nerve root became focally enhanced on magnetic resonance imaging (MRI) studies performed with gadolinium DTPA. Two men with low back pain and lumbar radiculopathy were examined with contrast-enhanced MRI studies, which showed intradural enhancement of the symptomatic nerve roots. In selected cases of lateral recess stenosis, focal radicular injury may be visualized on enhanced MRI as a result of a breakdown of the blood-brain barrier.

Interactions between 23S rRNA and tRNA in the ribosomal E site

Interactions between tRNA or its analogs and 23S rRNA in the large ribosomal subunit were analyzed by RNA footprinting and by modification-interference selection. In the E site, tRNA protected bases G2112, A2392, and C2394 of 23S rRNA. Truncated tRNA, lacking the anticodon stem-loop, protected A2392 and C2394, but not G2112, and tRNA derivatives with a shortened 3' end protected only G2112, but not A2392 or C2394. Modification interference revealed C2394 as the only accessible nucleotide in 23S rRNA whose modification interferes with binding of tRNA in the large ribosomal subunit E site. The results suggest a direct contact between A76 of tRNA A76 and C2394 of 23S rRNA. Protections at G2112 may reflect interaction of this 23S rRNA region with the tRNA central fold.

Oxazolidinone resistance mutations in 23S rRNA of Escherichia coli reveal the central region of domain V as the primary site of drug action

Oxazolidinone antibiotics inhibit bacterial protein synthesis by interacting with the large ribosomal subunit. The structure and exact location of the oxazolidinone binding site remain obscure, as does the manner in which these drugs inhibit translation. To investigate the drug-ribosome interaction, we selected Escherichia coli oxazolidinone-resistant mutants, which contained a randomly mutagenized plasmid-borne rRNA operon. The same mutation, G2032 to A, was identified in the 23S rRNA genes of several independent resistant isolates. Engineering of this mutation by site-directed mutagenesis in the wild-type rRNA operon produced an oxazolidinone resistance phenotype, establishing that the G2032A substitution was the determinant of resistance. Engineered U and C substitutions at G2032, as well as a G2447-to-U mutation, also conferred resistance to oxazolidinone. All the characterized resistance mutations were clustered in the vicinity of the central loop of domain V of 23S rRNA, suggesting that this rRNA region plays a major role in the interaction of the drug with the ribosome. Although the central loop of domain V is an essential integral component of the ribosomal peptidyl transferase, oxazolidinones do not inhibit peptide bond formation, and thus these drugs presumably interfere with another activity associated with the peptidyl transferase center.

Hyperbaric oxygen preconditioning induces neuroprotection against ischemia in transient not permanent middle cerebral artery occlusion rat model

OBJECTIVE

This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia.

METHODS

Sixty male SD rats were used in this study. Thirty animals underwent transient middle cerebral artery occlusion (MCAO) and the other thirty permanent MCAO model. The rats were randomly allocated to 3 sub-groups: control group (n = 10), HBO-3 group (n = 10), and HBO-5 group (n = 10). The animals in HBO-3 and HBO-5 groups received 1 hour hyperbaric oxygenation at 2.5 atmosphere absolute (ATA) in 100% oxygen every day for 3 and 5 days, respectively. The animals in the control group received sham treatments. 24 hours after the last HBO, transient MCAO (120 min) and permanent MCAO were induced by introducing a 3-0 nylon monofilament suture through internal carotid artery based on the Koizumi technique. The neurological outcome was evaluated until 24 hours after reperfusion in transient MCAO rats and ischemia in permanent MCAO rats. The infarct volume was then assessed by TTC staining.

RESULTS

In transient MCAO rats, the neurological outcome in both the HBO-3 and HBO-5 groups was better than that of the control group (P < 0.05 and 0.001). The infarct volume decreased from 171.5 +/- 113 mm3 to 40.6 +/- 49.9 mm3(P < 0.05) in the HBO-3 group and 16.2 +/- 28.8 mm3(P < 0.01) in the HBO-5 group. There were no significant differences in neurological outcome and infarct volume among the three groups in permanent MCAO rats.

CONCLUSIONS

The present study demonstrated that HBO preconditioning can induce ischemic tolerance in transient not permanent MCAO rats in a "dose-dependent" manner.

Evaluation of intrathecal gadolinium-enhanced MR cisternography in a rabbit model of traumatic nasoethmoidal CSF fistula

This pilot study details the feasibility of intrathecal gadopentetate dimeglumine (Gd) administration in the detection of posttraumatic cerebrospinal fluid (CSF) fistula in an animal model. Five rabbits were used in this study. An attempt was made to create a traumatic CSF fistula surgically via a nasal approach. Seven days following the procedure, images of the cranium in sagittal and coronal planes were obtained utilizing a 1.9 T magnetic resonance (MR) imaging scanner before and after intrathecal injection of 16 pmol Gd. Following the imaging study, the animals were euthanized and grossly sectioned coronally to search for fistula formation. One animal died on the third day following the surgical procedure. The other four rabbits underwent the MR and gross pathologic study. Diagnosis of the fistula by intrathecal Gd-enhanced MR imaging was successful in two rabbits; this finding was confirmed by gross pathologic examination. No fistula was detected on either intrathecal Gd-enhanced MR imaging or on pathologic study in the remaining two rabbits. Intrathecal enhanced MR cisternography is a potentially promising technique for the evaluation of posttraumatic CSF fistulae.

Resistance mutations in 23 S rRNA identify the site of action of the protein synthesis inhibitor linezolid in the ribosomal peptidyl transferase center

Oxazolidinones represent a novel class of antibiotics that inhibit protein synthesis in sensitive bacteria. The mechanism of action and location of the binding site of these drugs is not clear. A new representative of oxazolidinone antibiotics, linezolid, was found to be active against bacteria and against the halophilic archaeon Halobacterium halobium. The use of H. halobium, which possess only one chromosomal copy of rRNA operon, allowed isolation of a number of linezolid-resistance mutations in rRNA. Four types of linezolid-resistant mutants were isolated by direct plating of H. halobium cells on agar medium containing antibiotic. In addition, three more linezolid-resistant mutants were identified among the previously isolated mutants of H. halobium containing mutations in either 16 S or 23 S rRNA genes. All the isolated mutants were found to contain single-point mutations in 23 S rRNA. Seven mutations affecting six different positions in the central loop of domain V of 23 S rRNA were found to confer resistance to linezolid. Domain V of 23 S rRNA is known to be a component of the ribosomal peptidyl transferase center. Clustering of linezolid-resistance mutations within this region strongly suggests that the binding site of the drug is located in the immediate vicinity of the peptidyl transferase center. However, the antibiotic failed to inhibit peptidyl transferase activity of the H. halobium ribosome, supporting the previous conclusion that linezolid inhibits translation at a step different from the catalysis of the peptide bond formation.

[The changes in respiratory cycle, ventilation volume and blood analysis after bronchoalveolar lavage in dogs with steam inhalation injury]

OBJECTIVE

The changes in respiration cycle, ventilation volume and blood analysis after bronchoalveolar lavage(BAL) in dogs with steam induced inhalation injury were investigated to explore ways of treating inhalation injury.

METHODS

A bronchoscope was introduced down to the openings of the tertiary-quarternary bronchioles, and controlled volume BAL with drugs was done.

RESULTS

The inspiration time (Ti) and respiration cycle (Te) at 30, 60, 90 minutes after BAL were significantly lower than those of pre-BAL(P < 0.05), and respiration rate (RR) post-BAL at the same time points was markedly higher than that of pre-BAL(P < 0.05 or P < 0.01). The inspiratory minute ventilation volume (Vi) and expiratory minute ventilation volume (Ve) at 30 to 60 minutes after BAL were obviously increased as compared to pre-BAL(P < 0.01-P < 0.05); Vi and Ve at 90 minutes after BAL were also higher than those of pre-BAL, but there was no significant difference between them. The PaO2 at 30 minutes after BAL declined obviously as compared to pre-BAL(P < 0.05), and then rose gradually to approach pre-BAL level compared with pre-BAL. No significant changes were found in the expiration time (Te), ration of Ti to Te (Ti/Te), inspiratory tidal volume (Vti), expiratory tidal volume (Vte), PaCO2 and pH between values before and after BAL at all time points.

CONCLUSION

Controlled volume BAL with mixed drugs could improve lung alveolar ventilation, and it might have an excitory effect on respiration with potential clinical value.

Intrathecal gadolinium-enhanced MR myelography and cisternography: a pilot study in human patients

OBJECTIVE

This study was designed to evaluate the safety, MR imaging characteristics, and clinical response to intrathecal gadopentetate dimeglumine (gadolinium) administration in human patients.

SUBJECTS AND METHODS

Eleven adult patients were included in this prospective study. Via lumbar puncture, a single dose of either 0.2 ml, 0.5 ml, or 1.0 ml of gadolinium (500 mmol/l) mixed with 5 ml of previously removed CSF was slowly injected into the lumbar subarachnoid space. Immediate and delayed MR imaging were subsequently carried out using a 1.0-T magnet.

RESULTS

No patient manifested gross behavioral changes, neurologic alterations, or seizure activity. The intrathecal gadolinium-enhanced MR myelography revealed disk herniation (n = 4), posttraumatic spinal stenosis (n = 3), postsurgical noncommunicating cyst (n = 1), myelitis (n = 1), intradural extramedullary mass formation (n = 1), and intradural vascular malformation (n = 1).

CONCLUSION

This pilot study shows the relative safety and feasibility of low-dose intrathecal gadolinium administration. The potential clinical applications include the evaluation of obstructions and communications of the subarachnoid space, spontaneous or traumatic CSF leaks, and CSF dynamics. Additional animal and human studies must be performed to further evaluate the long-term safety and to prove the clinical applications of this procedure in a larger number of subjects.

HOS5-a negative regulator of osmotic stress-induced gene expression in Arabidopsis thaliana

Osmotic stress activates the expression of many plant genes through ABA-dependent as well as ABA-independent signaling pathways. We report here the characterization of a novel mutant of Arabidopsis thaliana, hos5-1, which exhibits increased expression of the osmotic stress responsive RD29A gene. The expression of several other stress genes are also enhanced by the hos5-1 mutation. The enhanced expression is specific to ABA and osmotic stress because low temperature regulation of these genes is not altered in the mutant. Genetic analysis indicated that hos5-1 is a recessive mutation in a single nuclear gene on chromosome III. Double mutant analysis of hos5-1 and the ABA-deficient aba1-1 as well as the ABA-insensitive abi1-1 mutant indicated that the osmotic stress hypersensitivity of hos5-1 is not affected by ABA deficiency or insensitivity. Furthermore, combined treatments of hos5-1 with ABA and osmotic stress had an additive effect on RD29A-LUC expression. These results suggest that the osmotic stress hypersensitivity in hos5-1 may be ABA-independent. The germination of hos5-1 seeds was more resistant to ABA. However, the hos5-1 mutation did not influence stomatal control and only slightly affected the regulation of growth and proline accumulation by ABA. The hos5-1 mutation reveals a negative regulator of osmotic stress-responsive gene expression shared by ABA-dependent and ABA-independent osmotic stress signaling pathways.

The effects of N(G)-nitro-L-arginine-methyl ester on neurologic and histopathologic outcome after transient spinal cord ischemia in rabbits

Little is known about the role of nitric oxide in the pathophysiology of spinal cord ischemia. We evaluated the effects of nitric oxide synthase (NOS) inhibition by N(G)-nitro-L-arginine-methyl ester (L-NAME) in rabbits whose abdominal aorta was occluded for 20 min (Experiment 1) or 25 min (Experiment 2). In Experiment 1, the L-NAME group (n = 6) received 3 mg/kg i.v. L-NAME, followed by an i.v. infusion of 3 mg x kg(-1). h(-1) until 6 h after reperfusion. Ischemia was induced 20 min after the start of L-NAME. The phenylephrine group (n = 6) received phenylephrine to maintain comparable blood pressure. The control group (n = 6) received saline. In Experiment 2, L-NAME (3 mg/kg i.v. L-NAME, followed by an i.v. infusion of 3 mg x kg(-1). h(-1) until 6 h after reperfusion) and phenylephrine groups (n = 6 each) were studied. Ischemia was induced 100 min after the start of L-NAME. Forty-eight hours after reperfusion, hindlimb motor function and histopathology of the spinal cord were examined. In Experiment 1, L-NAME and phenylephrine both improved neurologic outcome, with higher intraischemic blood pressures than saline. In Experiment 2, L-NAME worsened the neurologic and histopathologic outcome compared with phenylephrine. Attenuation of damage by L-NAME in Experiment 1 may be attributable to an intraischemic blood pressure increase. The worse outcome with L-NAME in Experiment 2 suggests that NOS inhibition exacerbates ischemic spinal cord damage.

IMPLICATIONS

Nonselective inhibition of nitric oxide synthase activity has aggravating effects on the neurologic and histopathologic outcome after transient spinal cord ischemia.

Effects of graded suppression of the EEG with propofol on the neurological outcome following incomplete cerebral ischaemia in rats

We evaluated the relation between dose and response for the neuroprotective effect of propofol in a rat model with incomplete cerebral ischaemia. For clarification of the mechanism of neuroprotection, plasma catecholamines and tumour necrosis factor-alpha levels were measured. Three doses (low, moderate and high-dose) of propofol were tested. These produced, respectively, a low amplitude, slowing and a burst-suppression pattern of electroencephalographic activity. Incomplete cerebral ischaemia was produced by right carotid artery occlusion combined with haemorrhagic hypotension (35 mmHg) for 30 min. Neurological outcome at 72 h post-ischaemia in the high-dose group was significantly better than that in both low-dose and moderate-dose groups. Propofol exhibited a trend in the dose-related attenuation of the increases in plasma adrenaline and noradrenaline during ischaemia. Tumour necrosis factor-alpha increased during and after ischaemia in all groups with no intergroup differences. The results indicate that a burst-suppression dose of propofol provides neuroprotection. The protective effect can not be completely explained by the attenuating effect on circulating catecholamines.

Evaluation of a safety educational programme for the prevention of pesticide poisoning

The causal factors of pesticide poisoning in spraymen usually include sloppy handling, leakage of sprayers and a lack of personal protection, as well as of a knowledge about pesticide toxicity. This paper outlines the results of a safety educational programme to prevent pesticide poisoning among Chinese village spraymen in 1991 and 1992. The programme consisted of two parts: an interview of 3,286 trained subjects who were surveyed before and after the education courses, and a survey on the prevalence of pesticide poisoning among spraymen in 10 villages in 1991 and 1992, respectively. The results showed a general improvement in the knowledge about pesticide toxicity and safe use among the surveyed subjects. The prevalence of pesticide poisoning among the surveyed spraymen decreased from 1.05% in 1991 to 0.25% in 1992. Moreover, a 68.2% reduction of pesticide poisoning cases was observed in 10 villages in 1992. The success of the safety educational programme proved that education is an effective measure for preventing pesticide poisoning.

Protective effects of Celsior in lung transplantation

BACKGROUND

Celsior is a new preservation solution for heart transplants that recently has been shown also to improve protection of pulmonary grafts. As these data were obtained in isolated lung preparations, we sought to perform further tests with an in vivo model of allogeneic lung transplantation.

METHODS

The left lungs of 41 rats were either transplanted immediately after harvest (controls) or flushed with and cold stored in Celsior or the blood-based Wallwork solution for 5 or 12 hours. Lungs were then reperfused for 30 minutes, after which ligation of the contralateral pulmonary artery and bronchus made the recipient rat exclusively dependent on the transplanted lung. Assessment of preservation was made on functional (blood gases, pulmonary hemodynamics) and structural (dry-to-weight ratio, light microscopy, myeloperoxidase [MPO] content) end points.

RESULTS

The protective effects of Celsior were primarily manifest, once the contralateral lung had been functionally excluded, as a better preservation of oxygen tensions in the 5-hour storage experiments (416 +/- 52 mm Hg vs 406 +/- 59 mm Hg in controls [p = NS] and vs 239 +/- 34 mm Hg in Wallwork [p < 0.05 vs the 2 other groups]) and a smaller increase in pulmonary vascular resistance in the 12-hour storage experiments (10.2 +/- 4.1 mm Hg/mL/minute vs 3.2 +/- 1.1 mm Hg/mL/minute in controls [p = NS] and vs 23.1 +/- 4.3 mm Hg/mL/minute in Wallwork [p < 0.02 vs Celsior, p < 0.002 vs controls]). Survival was also longer in the 12-hour preserved Celsior group. Other end points were not significantly different between the two preservative solutions.

CONCLUSION

These data support the efficacy of Celsior as a flush-out and storage solution for pulmonary grafts. Given its previously documented ability to adequately preserve heart transplants, Celsior might provide a unified "solution" to thoracic organ preservation.

Cold-regulated gene expression and freezing tolerance in an Arabidopsis thaliana mutant

Low temperature is an important environmental factor influencing plant growth and development. In this study, we report the characterization of a genetic locus, HOS2, which is defined by three Arabidopsis thaliana mutants. The hos2-1, hos2-2 and hos2-3 mutations result in enhanced expression of RD29A and other stress genes under low temperature treatment. Gene expression in response to osmotic stress or ABA is not affected in the hos2 mutants. Genetic analysis indicates that the hos2 mutations are recessive and in a nuclear gene. Compared with the wild-type plants, the hos2-1 mutant plants are less capable of developing freezing tolerance when treated with low non-freezing temperatures. However, the hos2-1 mutation does not impair the vernalization response. These results indicate that HOS2 is a negative regulator of low temperature signal transduction important for plant cold acclimation.

Evaluation of gadopentetate dimeglumine magnetic resonance cisternography in an animal model: preliminary report

RATIONALE AND OBJECTIVES

To evaluate magnetic resonance (MR) imaging characteristics of the cisternal administration of gadopentetate dimeglumine (gadolinium) in a small experimental animal.

METHODS

Four female New Zealand White rabbits were used for this experiment. Each rabbit received a single dose of intrathecal gadolinium (doses ranged from 75-100 micromol) via a cisternal puncture. Immediate and delayed sagittal and axial T1-weighted images of the brain and cervical spinal cord were acquired on a 2 Tesla CSI magnet.

RESULTS

All the rabbits tolerated the experiment well, without significant alterations in behavior or seizure activity. During the early phase of imaging, subarachnoid space enhancement was observed over the surface of the brain parenchyma and spinal cord on T1-weighted images. Gradual diffusion of the gadolinium into the cranial parenchyma was seen on the delayed MR studies (45 minutes-6 hours), as revealed by progressive generalized enhancement of the brain. Sustained enhancement of gray matter of the spinal cord was observed.

CONCLUSION

This study illustrates that there is no barrier between the cerebrospinal fluid (CSF) and the brain-spinal cord with regard to gadolinium. Possible practical applications for gadolinium-enhanced MR myelography or cisternography include the assessment of communication or obstruction of CSF pathways, subarachnoid space CSF flow pattern analysis, spontaneous or acquired CSF fistula evaluation, evaluation of the intercommunication of central nervous system cystic structures bordering on CSF pathways, and the study of the dynamics of gadolinium diffusion in the central nervous system parenchyma.

Interaction of osmotic stress, temperature, and abscisic acid in the regulation of gene expression in Arabidopsis

The impact of simultaneous environmental stresses on plants and how they respond to combined stresses compared with single stresses is largely unclear. By using a transgene (RD29A-LUC) consisting of the firefly luciferase coding sequence (LUC) driven by the stress-responsive RD29A promoter, we investigated the interactive effects of temperature, osmotic stress, and the phytohormone abscisic acid (ABA) in the regulation of gene expression in Arabidopsis seedlings. Results indicated that both positive and negative interactions exist among the studied stress factors in regulating gene expression. At a normal growth temperature (22 degrees C), osmotic stress and ABA act synergistically to induce the transgene expression. Low temperature inhibits the response to osmotic stress or to combined treatment of osmotic stress and ABA, whereas low temperature and ABA treatments are additive in inducing transgene expression. Although high temperature alone does not activate the transgene, it significantly amplifies the effects of ABA and osmotic stress. The effect of multiple stresses in the regulation of RD29A-LUC expression in signal transduction mutants was also studied. The results are discussed in the context of cold and osmotic stress signal transduction pathways.