Characterizing tuberculosis genotype clusters along the United States-Mexico border.

We examined the growth of tuberculosis (TB) genotype clusters during 2005-2010 in the United States, categorized by country of origin and ethnicity of the index case and geographic proximity to the US-Mexico border at the time of TB diagnosis. Nationwide, 38.9% of cases subsequent to Mexico-born index cases were US-born. Among clusters following US-born Hispanic and US-born non-Hispanic index cases, respectively 29.2% and 5.3% of subsequent cluster members were Mexico-born. In border areas, the majority of subsequent cases were Mexico-born following US-born Hispanic (56.4%) and US-born non-Hispanic (55.6%) index cases. These findings suggest that TB transmission commonly occurs between US-born and Mexico-born persons. Along the US-Mexico border, prioritizing TB genotype clusters following US-born index cases for investigation may prevent subsequent cases among both US-born and Mexico-born persons.

Vestibular functioning and migraine: pilot study comparing those with and without vertigo.

BACKGROUND: The current study compared a migrainous vertigo group with a migraine without vertigo group. It was hypothesised that those with migrainous vertigo would have more abnormal test results during a non-migrainous period than those who suffer from migraine without vertigo. METHODS: Both groups, comprising 10 participants each, were tested using: the gaze stabilisation test, dynamic visual acuity test, sensory organisation test, head shake sensory organisation test and functional gait assessment. RESULTS: Eighteen females and 2 males aged 18-53 years participated. There were no significant differences between the two groups for the dynamic visual acuity test, sensory organisation test or head shake sensory organisation test. However, mean dynamic visual acuity loss was greater in both groups than in a normal population, and the head shake sensory organisation (sway) test was well below the normal mean. The functional gait assessment showed a significant difference (p = 0.0025) between the two groups. CONCLUSION: Both groups showed abnormalities in vestibular functioning compared with norms, suggesting that both had some degree of vestibular dysfunction. However, vestibular dysfunction was greater in the migrainous vertigo group than in the migraine without vertigo group, as evidenced by differences in functional gait assessment.

Vestibular functioning and migraine: comparing those with and without vertigo to a normal population.

OBJECTIVE: This study compared vestibular functioning in a migrainous vertigo group, a migraine without vertigo group and a control group. It was hypothesised that the migrainous vertigo group would perform worse in tests of vestibular function and gait than the other groups during a non-migrainous period. METHODS: Sixty-six participants (22 per group) were assessed using the head shake sensory organisation test, the gaze stabilisation test, the dynamic visual acuity test and the functional gait assessment. Separate analyses of variance and planned pair-wise comparisons (alpha = 0.05) were performed. RESULTS: There was a difference between the results of the non-migraine group and the two migraine groups for the gaze stabilisation pitch test (p < 0.003), in which the control group showed faster head movement. There were also group differences in functional gait (p < 0.0001); the control group scored highest and the migrainous vertigo group scored lowest. There were no differences in the vestibular spinal reflex and balance tests. CONCLUSION: These findings indicate underlying differences in the vestibular ocular reflexes and function of migraine sufferers compared with those who do not suffer migraines, but the difference is most pronounced for those with migrainous vertigo. This suggests that vestibular rehabilitation for migrainous vertigo should focus on vestibular ocular reflexes and functional retraining.

Surfer's myelopathy: a radiologic study of 23 cases.

BACKGROUND AND PURPOSE: Surfing is an uncommon cause of an acute nontraumatic myelopathy. This study describes the MR imaging characteristics and clinical correlates in 23 subjects with surfer's myelopathy. MATERIALS AND METHODS: This was a retrospective review of 23 cases of surfer's myelopathy from 2003-2012. Spinal cord MR imaging characteristics and neurologic examinations with the use of the American Spinal Injury Association scale were reviewed. Logistic regression was used to determine associations between MR imaging characteristics, American Spinal Injury Association scale, and clinical improvement. RESULTS: All subjects (19 male, 4 female; mean age, 26.3 ± 7.4 years) demonstrated "pencil-like," central T2-hyperintense signal abnormalities in the spinal cord extending from the midthoracic region to the conus with associated cord expansion and varying degrees of conus enlargement on spinal cord MR imaging within 24 hours of symptom onset. T1 signal was normal. Faint gadolinium enhancement was present in a minority. Although there was a strong correlation between initial American Spinal Injury Association score and clinical improvement (P = .0032), MR imaging characteristics were not associated with American Spinal Injury Association score or clinical improvement. CONCLUSIONS: Surfer's myelopathy should be considered in the radiographic differential diagnosis of a longitudinally extensive T2-hyperintense spinal cord lesion. MR imaging characteristics do not appear to be associated with severity on examination or clinical improvement.

Genetically encoded fluorescent sensors of membrane potential.

Imaging activity of neurons in intact brain tissue was conceived several decades ago and, after many years of development, voltage-sensitive dyes now offer the highest spatial and temporal resolution for imaging neuronal functions in the living brain. Further progress in this field is expected from the emergent development of genetically encoded fluorescent sensors of membrane potential. These fluorescent protein (FP) voltage sensors overcome the drawbacks of organic voltage sensitive dyes such as non-specificity of cell staining and the low accessibility of the dye to some cell types. In a transgenic animal, a genetically encoded sensor could in principle be expressed specifically in any cell type and would have the advantage of staining only the cell population determined by the specificity of the promoter used to drive expression. Here we critically review the current status of these developments.

Three fluorescent protein voltage sensors exhibit low plasma membrane expression in mammalian cells.

Three first-generation fluorescent protein voltage sensitive probes (FP-voltage sensors) were characterized in mammalian cells. Flare, a Kv1.4 variant of FlaSh [Siegel MS, Isacoff EY. Neuron 1997;19(October (4)):735-41], SPARC [Ataka K, Pieribone VA. Biophys J 2002;82(January (1 Pt 1)):509-16], and VSFP-1 [Sakai R, Repunte-Canonigo V, Raj CD, Knopfel T. Eur J Neurosci 2001;13(June (12)):2314-18] were expressed, imaged and voltage clamped in HEK 293 cells and in dissociated hippocampal neurons. We were unable to detect a signal in response to changes in membrane potential after averaging16 trials with any of the three constructs. Using the hydrophobic voltage sensitive dye, di8-ANEPPS, as a surface marker, confocal analyses demonstrated poor plasma membrane expression for Flare, SPARC and VSFP-1 in both HEK 293 cells and dissociated hippocampal neurons. Almost all of the expressed FP-voltage sensors reside in internal membranes in both cell types. This internal expression generates a background fluorescence that increases the noise in the optical measurement.

Activators of viral gene expression in polarized epithelial monolayers identified by rapid-throughput drug screening.

Epithelial polarity and tight junction formation limit the ability of adenovirus, retrovirus and adeno-associated virus (AAV) to deliver and express virally encoded genes. Using an extended half-life luciferase assay and high-throughput luminometry, we screened 23 000 compounds and natural product extracts as potentiators to overcome this barrier. Seven strong activators were discovered (up to several hundred fold above control) and two of these exhibited spectrum of activity in multiple cell types (HeLa (human cervical carcinoma), cystic fibrosis bronchial epithelial (human bronchial), HT29 (human colonic carcinoma), Calu3 (airway serous glandular)). Enhanced transduction by unrelated gene transfer vectors (adenovirus, lentivirus, AAV, liposomal) was also observed. These results establish a strategy for identifying compounds that improve viral gene transfer to resistant cell types, and provide new tools for examining epithelial defense against viral infection. The compounds should have broad usefulness in experimental therapies for cancer and genetic diseases.

Seasonal and spatial variability in Lake Michigan sediment small-subunit rRNA concentrations.

We have used molecular biological methods to study the distribution of microbial small-subunit rRNAs (SSU rRNAs), in relation to chemical profiles, in offshore Lake Michigan sediments. The sampling site is at a depth of 100 m, with temperatures of 2 to 4 degrees C year-round. RNA extracted from sediment was probed with radiolabeled oligonucleotides targeting bacterial, archaeal, and eukaryotic SSU rRNAs, as well as with a universal probe. The coverage of these probes in relation to the present sequence database is discussed. Because ribosome production is growth rate regulated, rRNA concentrations are an indicator of the microbial populations active in situ. Over a 1-year period, changes in sedimentary SSU rRNA concentrations followed seasonal changes in surface water temperature and SSU rRNA concentration. Sedimentary depth profiles of oxygen, reduced manganese and iron, and sulfate changed relatively little from season to season, but the nitrate concentration was approximately fivefold higher in April and June 1997 than at the other times sampling was done. We propose that sediment microbial SSU rRNA concentrations at our sampling site are influenced by seasonal inputs from the water column, particularly the settling of the spring diatom bloom, and that the timing of this input may be modulated by grazers, such that ammonia becomes available to sediment microbes sooner than fresh organic carbon. Nitrate production from ammonia by autotrophic nitrifying bacteria, combined with low activity of heterotrophic denitrifying bacteria in the absence of readily degradable organic carbon, could account for the cooccurrence of high nitrate and low SSU rRNA concentrations.

Microbiological, molecular biological and stable isotopic evidence for nitrogen fixation in the open waters of Lake Michigan.

We have used a combination of microbiological, molecular biological and stable isotope methods to relate specific microbial populations to elemental cycling at an offshore site in Lake Michigan. Several lines of evidence suggest that atmospheric N2 may be a significant source of nitrogen to the lake. Particulate organic nitrogen (PON) at approximately equals 10-15m depth in July and October had a delta15N of 0.5-1.5%o. These values closely reflect the 15N composition of atmospheric N2, suggesting biological nitrogen fixation. Historical data show a developing late-summer N:P minimum at approximately equals 15 m; low abundance of inorganic nitrogen relative to phosphorus favours species able to acquire atmospheric nitrogen. Microscopic examination of October water samples revealed abundant heterocystous cyanobacteria, including Nodularia sp. Potentially nitrogen-fixing Anabaena spp. have been found in Lake Michigan before but, to our knowledge, this is the first report of Nodularia. Finally, we have amplified both cyanobacterial and non-cyanobacterial nifH sequences (encoding the nitrogenase iron protein) from lakewater samples, evidence for the presence of bacteria capable of nitrogen fixation. The surface waters of Lake Michigan are considered to be phosphate limited in the stratified season and, under these conditions, energetically expensive nitrogen fixation is expected to be uncompetitive with assimilation of combined nitrogen. Our results suggest that, from both microbiological and biogeochemical perspectives, this may be an oversimplification.

Chromosome landing at the tomato Bs4 locus.

The tomato (Lycopersicon esculentum) Bs4 gene confers resistance to strains of Xanthomonas campestris pathovar vesicatoria that express the avirulence protein AvrBs4. As part of a map-based cloning strategy for the isolation of Bs4, we converted Bs4-linked amplified fragment length polymorphism (AFLP) and restriction fragment length polymorphism (RFLP) markers into locus-specific sequence-tagged-site (STS) markers. The use of these markers for the analysis of 1972 meiotic events allowed high-resolution genetic mapping within a 1.2-cM interval containing the target gene. Two tomato yeast artificial chromosome (YAC) clones, each harboring inserts of approximately 250 kb, were identified using the marker most closely linked to Bs4. YAC end-specific markers were established and employed to construct a local YAC contig. The ratio of physical to genetic distance at Bs4 was calculated to be 280 kb/cM, revealing that recombination rates in this region are about three times higher than the genome-wide average. Mapping of YAC end-derived markers demonstrated that the Bs4 locus maps within a region of 250 kb, corresponding to a genetic interval of 0.9 cM.

Structure-function analysis of the tobacco mosaic virus resistance gene N.

The tobacco N gene is a member of the Toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class of plant resistance (R) genes and confers resistance to tobacco mosaic virus (TMV). We investigated the importance of specific domains of N in inducing TMV resistance, by examining various N deletion and point mutations that introduce single amino acid substitution mutants in vivo. Our deletion analysis suggests that the TIR, NBS, and LRR domains play an indispensable role in the induction of resistance responses against TMV. We show that amino acids conserved among the Toll/IL-1R/plant R gene TIR domain and NBS-containing proteins play a critical role in N-mediated TMV resistance. Some loss-of-function N alleles such as the TIR deletion and point mutations in the NBS (G216A/E/V/R, G218R, G219D, K222E/N, and T223A/N) interfere with the wild-type N function and behave like dominant negative mutations. These F(1) plants mount a hypersensitive response (HR) that is indistinguishable from that of the wild-type N plants, yet TMV was able to move systemically, causing a systemic hypersensitive response (SHR). Many amino acid substitutions in the TIR, NBS, and LRR domains of N lead to a partial loss-of-function phenotype. These mutant plants mount delayed HR compared with the wild-type N plants and fail to contain the virus to the infection site. In addition, some partial loss-of-function alleles (W82S/A, W141S/A, G218V/S, and G219V) interfere with the wild-type N function, leading to SHR. The partial loss-of-function and dominant negative mutant alleles described in this report will be useful in furthering our understanding of the TIR-NBS-LRR class of R genes.

Alternatively spliced N resistance gene transcripts: their possible role in tobacco mosaic virus resistance.

The N gene, a member of the Toll-IL-1 homology region-nucleotide binding site-leucine-rich repeat region (LRR) class of plant resistance genes, encodes two transcripts, N(S) and N(L), via alternative splicing of the alternative exon present in the intron III. The N(S) transcript, predicted to encode the full-length N protein containing the Toll-IL-1 homology region, nucleotide binding site, and LRR, is more prevalent before and for 3 hr after tobacco mosaic virus (TMV) infection. The N(L) transcript, predicted to encode a truncated N protein (N(tr)) lacking 13 of the 14 repeats of the LRR, is more prevalent 4-8 hr after TMV infection. Plants harboring a cDNA-N(S) transgene, capable of encoding an N protein but not an N(tr) protein, fail to exhibit complete resistance to TMV. Transgenic plants containing a cDNA-N(S)-bearing intron III and containing 3' N-genomic sequences, encoding both N(S) and N(L) transcripts, exhibit complete resistance to TMV. These results suggest that both N transcripts and presumably their encoded protein products are necessary to confer complete resistance to TMV.

Interactions between tobacco mosaic virus and the tobacco N gene.

The interaction between tobacco mosaic virus (TMV) and tobacco harbouring the N gene is a classical system for studying gene-for-gene interactions in disease resistance. The N gene confers resistance to TMV by mediating defence responses that function to limit viral replication and movement. We isolated the N gene and determined that N belongs to the nucleotide-binding-site-leucine-rich-repeat (NBS-LRR) class of plant disease resistance genes, and encodes both full-length and truncated proteins. Sequence homologies and mutagenesis studies indicated a signalling role for the N protein similar to that seen for proteins involved in defence responses in insects and mammals. The N gene confers resistance to TMV in transgenic tomato, demonstrating the use of the NBS-LRR class of disease resistance genes in engineering crop resistance. From the pathogen side of this interaction, the TMV 126 kDa replicase protein has been implicated as the avirulence factor that triggers N-mediated defence responses. We employed Agrobacterium-mediated expression strategies to demonstrate that expression of the putative helicase region of the replicase protein is sufficient to elicit N-mediated defences. The thermosensitivity of the N-mediated response to TMV is retained when induced by expression of this replicase fragment. Thus, both components of this gene-for-gene interaction are now available for studies that address the molecular mechanisms involved in N-mediated TMV resistance.

Purine and nucleoside metabolites from the Antarctic sponge Isodictya erinacea.

The bright yellow sponge Isodictya erinacea is one of several chemically defended sponges found on the benthos of McMurdo Sound, Antarctica. An investigation of the metabolites from this sponge has resulted in the isolation of purine and nucleoside metabolites, including the previously unreported erinacean (1) and p-hydroxybenzaldehyde. The latter metabolite has been demonstrated to cause a feeding deterrence behavior in Perknaster fuscus, the major predator of antarctic sponges.

Isolation, structure elucidation, and biological activity of the steroid oligoglycosides and polyhydroxysteroids from the Antarctic starfish Acodontaster conspicuus.

A total of 19 steroids, of which 13 steroidal oligoglycosides (nine new and four known) and six polyhydroxylated steroids (four new and two known), has been isolated from the Antarctic starfish Acodontaster conspicuus. The mixture is dominated by glycosides composed of steroidal aglycons having the hydroxyl groups typically disposed on one side of the tetracyclic nucleus, i.e., 3 beta,4 beta,6 alpha,8,15 beta-, with some having a sulfate at C-6, and differing in the side chains and/or in the disaccharide moieties that are usually attached at C-26, with some at C-28 and C-29. Those compounds are accompanied by minute amounts of glycosides with a delta 8(14)-double bond in the steroid, which is a structural feature not previously found among polyhydroxysteroids derived from starfish. Small amounts of six related unglycosidated polyhydroxysteroids and three higher-molecular-weight asterosaponins complete the composition of the mixture. The structures of the new compounds were determined by interpretation of their spectral data and by comparison with spectral data of known compounds. Eighteen of these compounds were evaluated for their ability to inhibit growth in Antarctic marine bacteria isolated from either the water column or the surfaces of benthic marine invertebrates. Of these compounds, 50% were active against at least one Antarctic marine bacterium. This suggests that these compounds may play an important role in deterring microbial fouling.

Organizing and documenting lactation support of NICU families.

A documentation tool designed for use by lactation consultants in the neonatal intensive-care unit provides an efficient and complete method for recording the progress of the mother and infant. It incorporates the research base into interventions that begin during the early postpartum period and continue through the preterm infant's hospital stay. The system for using this tool helps consultants in giving comprehensive and timely lactation support.

Metabolites from an Antarctic sponge-associated bacterium, Pseudomonas aeruginosa.

In an ongoing survey of the bioactive potential of microorganisms associated with marine invertebrates, the culture media of a sponge-associated bacterial strain of Pseudomonas aeruginosa was found to contain metabolites which inhibit the growth of several Gram-positive microorganisms. A series of diketopiperazines (1-6) including a new natural product (6) and two known phenazine alkaloid antibiotics (7 and 8) were isolated from the culture broth of this bacterium.

Molecular genetics of plant disease resistance.

Plant breeders have used disease resistance genes (R genes) to control plant disease since the turn of the century. Molecular cloning of R genes that enable plants to resist a diverse range of pathogens has revealed that the proteins encoded by these genes have several features in common. These findings suggest that plants may have evolved common signal transduction mechanisms for the expression of resistance to a wide range of unrelated pathogens. Characterization of the molecular signals involved in pathogen recognition and of the molecular events that specify the expression of resistance may lead to novel strategies for plant disease control.