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PubMed1983

Immotile cilia syndrome in children.

Nasal mucociliary function was studied in 46 children suffering from recurrent respiratory infections, sinusitis and otitis media. Mucociliary transport velocity was measured by a radioisotopic method using 99mTc-labelled human serum albumin as a tracer substance. In 31 patients mucociliary transport was markedly impaired, 0-5 mm/min (average 1.9 mm/min), whereas in healthy children it was 6-9 mm/min. Transmission electron microscopic studies of the cilia discovered many structural variations. Two patients, who did not have dextrocardia and who had had respiratory difficulties from birth onwards, had the immotile cilia syndrome, with total absence of dynein arms in the ciliary cross-sections. In the study of recurrent and chronic bronchitis, sinusitis and otitis media in children the radioisotopic method is recommended for initial examination and, if a lowered mucociliary activity is detected on both sides of the nose, a sample of nasal or bronchial mucosa should be taken for electron microscopic studies.

Adolescent↗
PubMed2000

The hnRNP 2H9 gene, which is involved in the splicing reaction, is a multiply spliced gene.

The hnRNP 2H9 gene products are involved in the splicing process and participate in early heat shock-induced splicing arrest. By combining low/high stringency hybridisation, database search, Northern and Western blotting it is shown that the gene is alternatively spliced into at least six transcripts: hnRNPs 2H9, 2H9A, 2H9B, 2H9C, 2H9D and 2H9E predicting proteins containing 346, 331, 297, 215, 145 and 139 amino acids, respectively. The hnRNP 2H9A cDNA sequence was used to obtain a genomic BAC clone and the structure of the hnRNP 2H9 gene was revealed by sequencing two subclones together spanning about 6.7 kb. The six transcripts are processed from at least 10, 10, 8, 7, 5 and 4 exons, respectively, with all intron/exon junctions obeying the 'GT-AG' rule. The hnRNP 2H9 and 2H9A proteins contain two RNA recognition motifs of the quasi-RRM type found in the two C-terminal qRRMs of the hnRNPs H, H' and F proteins. The hnRNP 2H9B protein has a partially deleted N-terminal qRRM, which is completely deleted in hnRNP 2H9C. hnRNPs 2H9D and 2H9E contain only one slightly modified C-terminal qRRM. Furthermore, the six proteins vary in their auxiliary domains outside the qRRMs. Western blotting indicates that the alternatively spliced transcripts give rise to different sets and levels of proteins expressed among various human cells and tissues. Due to their great structural variations the different proteins may thus possess different functions in the splicing reaction.

Alternative Splicing↗
PubMed1998

Loss in milk yield and related composition changes resulting from clinical mastitis in dairy cows.

Relationships between clinical mastitis and milk yield and composition in dairy cows were reviewed. Requirements for inclusion were: data had to be collected after 1975; dependent variables for milk yield and milk composition had to be defined at the cow level; mastitis cases had to be defined by clinical signs, and at least 250 lactations had to be considered. Twenty studies dealing with milk-yield loss and, for four of them, also with related composition changes were selected. Study populations, design of data collection, and analysis methods differed widely between studies. As expected from these differences--but also due to structural-variation factors such as type of pathogen, animal and production level--estimates for milk-yield losses differed in average magnitude and pattern. Literature data regarding changes in milk-fat % and total-protein % changes were contradictory. Critiques of materials and methods allowed us to propose some final recommendations for values to be used as basic inputs in economic calculations of losses caused by mastitis.

Animals↗
PubMed1995

Safe and effective infundibulotomy technique.

The ostiomeatal complex has been identified as an important anatomic region in the pathogenesis of sinusitis. Functional endoscopic techniques rely on removal of mucosal disease from this site to improve drainage and aeration. Structural variations and the use of a sharp blade to create the infundibulotomy can result in inadvertent injury to the orbit. To avoid orbital penetration we perform the infundibulotomy with a curved, blunt dental elevator and displace the uncinate with its medial and lateral mucosa toward the middle turbinate. This stretches the infundibulum to reveal the maxillary ostium at its depth. The remaining mucosal attachments of the uncinate process are then incised under direct vision, and the complex is resected, creating an initial wide antrostomy. This technique has avoided orbital penetration in 700 cases in patients with early or late stages of mucosal disease.

Endoscopy↗
PubMed1997

Binding of new cirazoline derivative to imidazoline receptors from human brain.

Imidazoline compounds are known to interact with alpha 2-adrenoceptors as well as with specific non-adrenergic binding sites. Such binding sites are present in the brain and in peripheral tissues. Hypotensive effects of imidazolines were shown to be related to specific interaction with imidazoline binding sites within the brainstem. Heterogeneity of these sites based on differences in selectivities was reported. In order to facilitate the characterization of human brain imidazoline receptors, we synthetized new ligands by substitutions on the cirazoline phenyl ring. Affinities of these cirazoline derivatives were determined in two imidazoline binding site models, namely the human brain and the rabbit kidney. Interaction of these compounds with imidazoline binding sites from the human brain appeared more sensitive to structural variations of the imidazoline than those with rabbit kidney sites. Moreover, no correlation was found between affinities for imidazoline binding sites and those for alpha 2-adrenoceptors of the rat brain. Arylazide derivative of 2-(5-amino-2-methyl-phenoxymethyl)-imidazoline exhibited a higher affinity for human brain imidazoline binding sites than for human brain alpha 2-adrenoceptors. Photoincorporation of this azido-compound in human brain imidazoline binding sites was achieved and blockade of [3H]idazoxan imidazoline specific binding observed. These new tools may allow fine characterization of the different subtypes of imidazoline binding proteins.

Adrenergic alpha-Agonists↗
PubMed2000

Adaptive information processing in microtubule networks.

Microtubule networks provide a wide range of microskeletal and micromuscular functionalities. Evidence from a number of directions suggests that they can also serve as a medium for intracellular signaling processing. The model presented here comprises an empirically motivated representation of microtubule growth dynamics, an abstract representation of signal processing, and a feedback learning mechanism that we refer to as adaptive self-stabilization. The growth model mimics the dynamic instability picture of microtubule formation and decomposition, but as modulated by the binding activity of microtubule associated proteins (or MAPs). The signal processing submodel treats each microtubule as a string of linked discrete oscillators capable of propagating signals that are introduced, manipulated, and extracted by bound MAP activity. Adaptive self-stabilization is essentially feedback acting on signal processing capabilities via the growth dynamics. The network is presented with a training set of patterns. If the input-output behavior is satisfactory MAP binding affinity increases, thereby stabilizing the network structure; otherwise the binding affinity decreases, allowing for more structural variation. The results obtained suggest that adaptive capabilities are practically inevitable in microtubule networks, a conclusion strengthened by the fact that the signal processing and growth dynamics mechanisms available in nature are undoubtedly much richer than those represented in the model.

Adaptation, Physiological↗
PubMed2000

Establishment and characterization of an Oklahoma isolate of Anaplasma marginale in cultured Ixodes scapularis cells.

Anaplasma marginale is a tick-borne hemoparasite of cattle worldwide. The Virginia isolate of A. marginale was propagated previously in a cell line derived from embryos of the tick, Ixodes scapularis. The cultured Anaplasma (VA-tc) was passaged continuously for over 4 years and retained its infectivity for cattle and antigenic stability. We report herein the continuous in vitro cultivation of a second isolate of A. marginale derived from a naturally infected cow in Oklahoma (OK-tc). Blood from the infected cow was subinoculated into a splenectomized calf and blood collected at peak parasitemia was frozen, thawed and used as inoculum on confluent tick cell monolayers. Colonies of Anaplasma were apparent in low numbers at 9 days post exposure (PE) and infection in monolayers reached 100% by 4-5 weeks PE. Cultures were passaged by placing supernatant onto fresh tick cell monolayers at a dilution of 1:5 or 1:10. By the third passage development of the OK-tc was similar to that of the VA-tc and a 1:5 dilution resulted in 100% infection in 10-12 days. Inoculation of OK-tc into a splenectomized calf caused clinical anaplasmosis and Dermacentor ticks that fed on this calf transmitted the organism to a second susceptible calf. Major surface proteins (MSPs) 1-5 of the OK-tc were compared with homologous proteins present on VA-tc and the erythrocytic stage of the Oklahoma isolate. The MSPs 1, 2, 4, 5 were conserved on the OK-tc but there was evidence for structural variation in MSP3 between the cultured and erythrocytic stage of Anaplasma. MSP2 and MSP3 were the major proteins recognized by serum from infected cattle. Two-dimensional gels also identified positional differences between VA-tc and OK-tc in MSP2 and MSP3. The OK-tc may have potential to be used as antigen for development of an improved vaccine for anaplasmosis in the South Central United States.

Anaplasma↗
PubMed2006

Cloning, sequencing and analysis of the 16S-23S rDNA intergenic spacers (IGSs) of two strains of Vibrio vulnificus.

According to the conserved sequences flanking the 3' end of the 16S and the 5' end of the 23S rDNAs, PCR primers were designed, and the 16S-23S rDNA intergenic spacers (IGSs) of two strains of Vibrio vulnificus were amplified by PCR and cloned into pGEM-T vector. Different clones were selected to be sequenced and the sequences were analyzed with BLAST and the software DNAstar. Analyses of the IGS sequences suggested that the strain ZSU006 contains five types of polymorphic 16S-23S rDNA intergenic spacers, namely, IGSGLAV, IGSGLV, IGSIA, IGSG and IGSA; while the strain CG021 has the same types of IGSs except lacking IGSA. Among these five IGS types, IGSGLAV is the biggest type, including the gene cluster of tRNAGlu-tRNALys-tRNAAla-tRNAVal; IGSGLV includes that of tRNAGlu-tRNALys-tRNAVal; IGSAG, tRNAAla-tRNAGlu; IGSIA, tRNAIle-tRNAAla; IGSG, tRNAGlu and IGSA, tRNAAla. Intraspecies multiple alignment of all the IGS sequences of these two strains with those of V. vulnificus ATCC27562 available at GenBank revealed several highly conserved sequence blocks in the non- coding regions flanking the tRNA genes within all of strains, most notably the first 40 and last 200 nucleotides, which can be targeted to design species-specific PCR primers or detection probes. The structural variations of the 16S-23S rDNA intergenic spacers lay a foundation for developing diagnostic methods for V. vulnificus.

Cloning, Molecular↗
PubMed1997

Foundations of chemical microscopy. 1. Solid-state characterization of 5-nitrobarbituric acid (dilituric acid) and its complexes with group IA and group IIA cations.

5-Nitrobarbituric acid (dilituric acid) has been used as a chemical microscopic reagent for the qualitative identification of alkali metal (Group IA) and alkaline earth (Group IIA) cations. This methodology was based on the characterization of observed crystal morphologies, since a unique crystal habit could be associated with each adduct product. To understand the scientific foundations which permitted chemical microscopy to function as a useful analytical technique, the products formed between dilituric acid and the Group IA and IIA cations were characterized using polarizing optical microscopy, powder X-ray diffraction, thermal analysis and solid-state nuclear magnetic resonance. It was found that the origins of the different crystal morphologies associated with each of the adduct arose from the ability of the systems to form various hydrate species, which could also contain structural variations due to cation/diliturate packing patterns.

Barbiturates↗
PubMed2001

Surface landmarks of brachial plexus: ultrasound and magnetic resonance imaging for supraclavicular approach with anatomical correlation.

The present study is able to describe a certain line, under which brachial plexus (BP) lies underneath in the supraclavicular region. A line drawn between midpoint of the sternocleidomastoid muscle to the midpoint of the clavicle was considered for BP. Surface landmarks were evaluated by applying ultrasound (US) on 30 volunteers (15 female, 15 male). Axial and sagittal views of BP were taken and distances between skin and BP were measured. Coronal magnetic resonance (MR) sections were taken from 7 volunteers according to the second line after applying two fat capsules on each line. The sonographic views were seen at the same line. Mean distances from skin were found as 16.5+/-0.7 mm for male and 14.5+/-0.5 mm for female volunteers. MR images were obtained bilaterally, which were parallel and posterior from sonographic lines. Surface landmarks, as presented in this study, are simple to accomplish and are not dependent on structural variations as external jugular vein.

Adult↗
PubMed1998

Phylogenetic development of the cochlea and its innervation.

Comparative studies of vertebrate hearing organs have enabled an integrated approach to difficult questions related to function. Recent evidence for the independent evolution of similar hearing-organ specializations, in particular hair-cell differentiation, has helped identify common problems of hearing receptors and put them in a new perspective. Evidence that cochlear amplification is an ancient phenomenon has widened the search for the motor mechanism involved. In this regard, different hypotheses are best examined by making optimal use of natural structural variations. Studies on the evolution of the efferent system have provided new routes to investigate its function.

Animals↗
PubMed1998

New results using Laue diffraction and time-resolved crystallography.

Several time-resolved crystallographic structures were determined over the past year, using a variety of trapping protocols and several data collection methods. A significant theme of recent time-resolved work is the importance of parallel comparative studies on the same protein, using different experimental protocols, in order to fully characterize the structural variation of the intermediates formed in the reaction pathway.

Bacterial Proteins↗
PubMed1995

A 26 kDa yeast DNA topoisomerase I fragment: crystallographic structure and mechanistic implications.

BACKGROUND: Type I DNA topoisomerases, divided mechanistically into two subfamilies, are ubiquitous enzymes that participate in replication and transcription. In addition to its role in these fundamental processes, the biological importance of eukaryotic DNA topoisomerase I is underscored by its identification as the target of the antitumor alkaloid camptothecin. An understanding of the mechanism of catalysis and interactions with camptothecin and other drugs has been hampered by a lack of detailed structural information. RESULTS: The three-dimensional structure of a 26 kDA fragment (residues 135 to about 363) of Saccharomyces cerevisiae DNA topoisomerase I has been determined at 1.9 A resolution. The fragment has a novel architecture comprising a concave platform and a pair of outlying V-shaped helices. Photocrosslinking and protein footprinting experiments show that the positively charged concave surface and the junction region of the V-shaped pair of helices contact DNA in the enzyme-DNA complex. CONCLUSIONS: Crystallographic, biochemical and genetic data indicate that this 26 kDa fragment of yeast DNA topoisomerase I is involved in complex formation between the enzyme and DNA, and probably also in camptothecin-enzyme-DNA ternary complex formation. A molecular model for protein-DNA interaction based on these data is proposed. The bipartite DNA-binding regions of the 26 kDa fragment may enable eukaryotic DNA topoisomerase I to adapt to sequence-dependent structural variations in its DNA substrates.

Camptothecin↗
PubMed1998

Crystal structure of the C2 domain from protein kinase C-delta.

BACKGROUND: The protein kinase C (PKC) family of lipid-dependent serine/theonine kinases plays a central role in many intracellular eukaryotic signalling events. Members of the novel (delta, epsilon, eta, theta) subclass of PKC isotypes lack the Ca2+ dependence of the conventional PKC isotypes and have an N-terminal C2 domain, originally defined as V0 (variable domain zero). Biochemical data suggest that this domain serves to translocate novel PKC family members to the plasma membrane and may influence binding of PKC activators. RESULTS: The crystal structure of PKC-delta C2 domain indicates an unusual variant of the C2 fold. Structural elements unique to this C2 domain include a helix and a protruding beta hairpin which may contribute basic sequences to a membrane-interaction site. The invariant C2 motif, Pro-X-Trp, where X is any amino acid, forms a short crossover loop, departing radically from its conformation in other C2 structures, and contains a tyrosine phosphorylation site unique to PKC-delta. This loop and two others adopt quite different conformations from the equivalent Ca(2+)-binding loops of phospholipase C-delta and synaptotagmin I, and lack sequences necessary for Ca2+ coordination. CONCLUSIONS: The N-terminal sequence of Ca(2+)-independent novel PKCs defines a divergent example of a C2 structure similar to that of phospholipase C-delta. The Ca(2+)-independent regulation of novel PKCs is explained by major structural and sequence differences resulting in three non-functional Ca(2+)-binding loops. The observed structural variation and position of a tyrosine-phosphorylation site suggest the existence of distinct subclasses of C2-like domains which may have evolved distinct functional roles and mechanisms to interact with lipid membranes.

Amino Acid Sequence↗
PubMedDate not supplied

Biophysical dose measurement using electron paramagnetic resonance in rodent teeth.

Electron paramagnetic resonance (EPR) dosimetry of human tooth enamel has been widely used in measuring radiation doses in various scenarios. However, there are situations that do not involve a human victim (e.g. tests for suspected environmental overexposures, measurements of doses to experimental animals in radiation biology research, or chronology of archaeological deposits). For such cases we have developed an EPR dosimetry technique making use of enamel of teeth extracted from mice. Tooth enamel from both previously irradiated and unirradiated mice was extracted and cleaned by processing in supersaturated KOH aqueous solution. Teeth from mice with no previous irradiation history exhibited a linear EPR response to the dose in the range from 0.8 to 5.5 Gy. The EPR dose reconstruction for a preliminarily irradiated batch resulted in the radiation dose of (1.4+/-0.2) Gy, which was in a good agreement with the estimated exposure of the teeth. The sensitivity of the EPR response of mouse enamel to gamma radiation was found to be half of that of human tooth enamel. The dosimetric EPR signal of mouse enamel is stable up at least to 42 days after exposure to radiation. Dose reconstruction was only possible with the enamel extracted from molars and premolars and could not be performed with incisors. Electron micrographs showed structural variations in the incisor enamel, possibly explaining the large interfering signal in the non-molar teeth.

Animals↗
PubMed2000

Comparison of N-[(11)C]methyl-norchloroepibatidine and N-[(11)C]methyl-2-(2-pyridyl)-7-azabicyclo[2.2.1]heptane with N-[(11)C]methyl-epibatidine in small animal PET studies.

Structural variations of the nicotinic acetylcholine receptor radioligand N-[(11)C]methyl-epibatidine were made to form (11)C-labeled N-methyl-norchloroepibatidine (N-methyl-NorchloroEPB) and N-methyl-2-(2-pyridyl)-7-azabicyclo[2.2.1]heptane (N-methyl-2PABH). Radiosyntheses were performed by methylation with high radiochemical purities (>98%) and with specific activities between 140 and 500 GBq/micromol at the end of synthesis. The radiochemical yield (decay-corrected, related to [(11)C]CH(3)I) was between 5 and 10%. Positively and negatively radiolabeled enantiomers were prepared in high optical purity (>98%ee) by labeling of the appropriate optically active substrates, which were obtained via chiral high performance liquid chromatography. For in vivo studies radioligands were administered intravenously in rats. Brain uptake curves were acquired and combined with blocking experiments. Brain uptake of N-[(11)C]methyl-NorchloroEPB was similar to that of N-[(11)C]methyl-EPB whereas N-[(11)C]methyl-2PABH with the modified pyridine ring had a significantly lower uptake.

Animals↗