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PubMed1997

Associations between body morphology and bone mineral density in premenopausal women.

UNLABELLED: To investigate whether body morphology, obesity and its long time evolution were associated with lumbar and femoral bone mineral density (BMD) in premenopausal women of the same age. DESIGN: Cross-sectional study. SUBJECTS: 72 healthy premenopausal women born in 1950 (42 years) with a regular physical activity. MEASUREMENTS: BMD measured by dual-X-ray absorptiometry (DEXA) at lumbar spine and proximal femur; body weight, body mass index (BMI), BMI at 20 years (BMI-20), increase in BMI since age of 20 (BMI->20), body circumferences (breast, waist, hip) and their ratios (WHR, BHR, WBR), smoking and alcohol intake. RESULTS: Lumbar spine BMD did not correlate with any anthropometric measurement. Femoral BMDs correlated positively with weight, BMI, BMI-20, breast, waist, WHR and BHR. The BMI-20 explained the 5% and the current BMI the 13% of variance of total femur BMD. After adjustment for weight or BMI, breast circumference and BHR remained significantly correlated with all femoral BMDs sites except neck. Weight was the best predictor for neck BMD (R2 = 0.08; p < 0.02), and BHR for Ward's triangle (R2 = 0.12; p < 0.01) and trochanter (R2 = 0.10; p < 0.001). Alcohol intake, cigarette smoking, and age of menarche were not related to BMDs. CONCLUSION: In premenopausal women of the same age, lumbar spine BMD was not associated with any anthropometric measurement. Greater BHR and its long time of evolution may be determinants of greater femoral BMD (trabecular), whereas body weight may be determinant of femoral neck BMD (cortical). Further studies are needed to determine whether large breast to hip ratio may be considered as a protective factor for femoral osteoporosis.

Absorptiometry, Photon↗
PubMed2002

Comprehensive analyses of a unique HIV-1-infected nonprogressor reveal a complex association of immunobiological mechanisms in the context of replication-incompetent infection.

We recently demonstrated that a unique HIV-1-infected nonprogressor was infected with a nonevolving replication-incompetent HIV-1 strain, showing a total absence of viral evolution in vivo. Potent immune responses against HIV-1 were observed in his PBMC, despite an apparent lack of viral replication for at least 8 years. His PBMC resisted superinfection with CCR5, CXCR4, and dual-tropic HIV-1 strains, although highly purified CD4+ T cells supported infection, but without any visible cytopathic effect. Potent noncytolytic CD8+ T cell antiviral activity was shown to protect his PBMC from productive infection. This activity was not mediated by several known chemokines or IFN-gamma, which were produced at high levels after PHA activation of his CD8+ T cells, indicating the action of other CAF-like CD8 factors. This antiviral activity was a memory response, induced by HIV-specific stimulation to similar levels observed by PHA stimulation, but absent in ex vivo resting T cells. Immunological mechanisms associated with this antiviral suppressive activity included vigorous Gag-specific helper T cell proliferative responses and high-level IFN-gamma release by both CD4 and CD8 T cells. These responses were broadly directed against multiple Gag epitopes, both previously reported and some novel epitopes. Strong HIV-specific helper T cell function was also associated with strong neutralizing antibodies. Understanding how to induce these protective immune responses in other individuals could provide a major step forward in the design of effective immunotherapies or vaccines against HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Structural and biochemical analysis of the Rv0805 cyclic nucleotide phosphodiesterase from Mycobacterium tuberculosis.

Cyclic nucleotide monophosphate (cNMP) hydrolysis in bacteria and eukaryotes is brought about by distinct cNMP phosphodiesterases (PDEs). Since these enzymes differ in amino acid sequence and properties, they have evolved by convergent evolution. Cyclic NMP PDEs cleave cNMPs to NMPs, and the Rv0805 gene product is, to date, the only identifiable cNMP PDE in the genome of Mycobacterium tuberculosis. We have shown that Rv0805 is a cAMP/cGMP dual specificity PDE, and is unrelated in amino acid sequence to the mammalian cNMP PDEs. Rv0805 is a dimeric, Fe(3+)-Mn(2+) binuclear PDE, and mutational analysis demonstrated that the active site metals are co-ordinated by conserved aspartate, histidine and asparagine residues. We report here the structure of the catalytic core of Rv0805, which is distantly related to the calcineurin-like phosphatases. The crystal structure of the Rv0805 dimer shows that the active site metals contribute to dimerization and thus play an additional structural role apart from their involvement in catalysis. We also present the crystal structures of the Asn97Ala mutant protein that lacks one of the Mn(2+) co-ordinating residues as well as the Asp66Ala mutant that has a compromised cAMP hydrolytic activity, providing a structural basis for the catalytic properties of these mutant proteins. A molecule of phosphate is bound in a bidentate manner at the active site of the Rv0805 wild-type protein, and cacodylate occupies a similar position in the crystal structure of the Asp66Ala mutant protein. A unique substrate binding pocket in Rv0805 was identified by computational docking studies, and the role of the His140 residue in interacting with cAMP was validated through mutational analysis. This report on the first structure of a bacterial cNMP PDE thus significantly extends our molecular understanding of cAMP hydrolysis in class III PDEs.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2002

Differential impedance spectroscopy for monitoring protein immobilization and antibody-antigen reactions.

This work describes the theoretical and experimental approaches for monitoring the interfacial biomolecular reaction between immobilized antibody and the antigen binding partner using novel differential impedance spectroscopy. The prerequisite of any biosensor is the immobilization of macromolecules onto the surface of a transducer. It is clear that the function of most macromolecules changes from what is observed in solution once immobilization has occurred. In the worst case, molecules entirely lose their binding activity almost immediately after immobilization. Certain conditions (e.g., denaturation, interfacial effects based on ionic strength, surface charge, dielectric constants, etc.) at interfaces are responsible for alterations of binding activity; it is not clear whether a combination of such processes is understood. However, these processes in combination must be reliably modeled in order to predict the outcome for most macromolecules. This work presents the theoretical and practical means for elucidating the surface reactivity of biomolecular reagents using ion displacement model with antibody-antigen (Ab-Ag) reaction as the test case. The Ab-Ag reaction was directly monitored using a dual-channeled, impedance analyzer capable of 1 measurement/s using covalent immobilization chemistry and polymer-modified electrodes in the absence of a redox probe. The evidence of Ab-Ag binding was revealed through the evolution of differential admittance. The surface loading obtained using the covalent immobilization chemistry was 9.0 x 10(16)/cm2, whereas with polymer-modified electrodes, the surface loading was 9.0 x 10(15)/cm2, representing a 10 times increase in surface reactivity. The proposed approach may be applicable to monitoring other surface interfacial reactions such as DNA-DNA interactions, DNA-protein interactions, and DNA-small molecule interactions.

Algorithms↗
PubMed1996

Understanding the forces driving medical group practice activities: an overview.

This article provides the historical context for examining the current forces driving medical group practice organizations. Prepayment has been around for some groups since the 1930s and the dual objectives of lowering costs and improving the quality of patient care were among the original reasons for forming group practices. Some of the basic issues for group practices today are discussed in light of evolution of this model of service delivery and the intensity of today's changing environment.

Group Practice↗
PubMed1997

Anterolateral dynamized instrumentation and fusion for unstable thoracolumbar and lumbar burst fractures.

STUDY DESIGN: A retrospective chart review of 36 patients treated with dynamized anterolateral instrumentation and fusion after decompression for thoracolumbar and lumbar burst fractures is presented. OBJECTIVES: To evaluate a device that allows continual bone graft vertebral endplate compression and determine its potential for healing in patients with thoracolumbar and lumbar burst fractures. SUMMARY OF BACKGROUND DATA: Anterior spinal surgery has led to implant adaptations. Such implants have undergone an evolution in hopes of improving the rate of healing and avoiding neurovascular catastrophes. METHODS: Thirty-six patients underwent anterior decompression dynamized instrumentation and fusion for thoracolumbar and lumbar burst fractures. This involved a dual-rod, quadrilateral, cross-linked frame that allows for continual compression but deters rotation and shear stresses. RESULTS: All patients healed solidly without instrumentation failure. An average recovery of 1.3 Frankel grades was recorded. Subsidence of bone graft vertebral endplate was less than in those placed in a trough. CONCLUSIONS: Dynamized load-sharing anterolateral Cotrel-Dubousset instrumentation led to solid bone graft healing without implant failure by allowing continual compression while deterring shear and rotational stresses.

Adult↗
PubMed1999

Cytogenetic analysis of chimeric antibody-producing CHO cells in the course of dihydrofolate reductase-mediated gene amplification and their stability in the absence of selective pressure.

Previously, the highest producing (HP) recombinant CHO subclones isolated at various methotrexate (MTX) levels showed different antibody production stability during long-term culture, although they were clonally derived from CS13 transformant. In this study, genetic basis for their difference in antibody production stability was investigated using southern blot hybridization and fluorescence in situ hybridization (FISH) techniques. Southern analysis of HP subclones revealed that light-chain (LC) and heavy-chain (HC) cDNAs were located closely within 23 kb on an amplification unit, and the configuration of LC and HC cDNAs within this amplification unit was not disrupted during long-term culture in the absence of MTX. However, when LC and HC genes were localized on the metaphase chromosomes of HP subclones using FISH, the amplified sequences were present as an extended array on diverse marker chromosomes. HP subclones selected at higher MTX level had more kinds of marker chromosomes. CS13*-002 isolated at 0.02 microM MTX had only one marker chromosome (m002), whereas CS13*-1.0 isolated at 1 microM MTX had five different ones (m10A, m10B, m10C, m10D, and m10E). Each marker chromosome showed different fate during long-term culture of HP subclones in the absence of MTX, resulting in different degrees of stability among the HP subclones. The m10A and m10B remained unchanged, whereas the others disappeared or evolved to variants with shortened amplified arrays. The cells containing stable marker chromosomes constituted dominant subpopulations in CS13*-1.0, and thereby CS13*-1.0 became most stable in regard to antibody production during long-term culture. Furthermore, our dual-color FISH showed that the telomeric ends of amplified arrays on the stable marker chromosomes were always surrounded by (TTAGGG)(n) sequences, indicating that (TTAGGG)(n) sequences are closely related to the stability and evolution of amplified sequences. Taken together, our data show that the assessment of genotypic stability of amplified CHO cells is a prerequisite for understanding their production stability during long-term culture in the absence of selection pressure.

Animals↗
PubMed1993

The evolution of the system of care for the aged in Denmark.

In Denmark, formal services are viewed as a right to be used by any member of that society who is in need of assistance, premised upon a societal model of mutual self-help. The focus here is on the dual themes of philosophical consistency and of transition in the formal system of services and delivery of care in Denmark. Denmark's system centers on meeting the basic needs of the elderly while enabling individuals to retain control over decisions regarding their own lives. It was effective during the economically expansive period of the 1960s and 1970s, but became less effective during the 1980s. Because of the economic necessity of cutting back on budgets, the national government has in fact attempted to define and redirect available choices in service delivery. The dual themes of consistency and dynamism are demonstrated through the case of a rural municipality in northwest Jutland during the prosperous period into the more economically limited period of the last decade and the present. Implications for informal social support and relationships between the aged and their families, friends, and neighbors in Denmark are explored.

Aged↗
PubMed1994

Hybridization of matrix-bound MM-creatine kinase with BB-creatine kinase and arginine kinase.

Dimeric rabbit muscle creatine kinase (MM-CK) was bound to CNBr-activated Sepharose 4B by one of its subunits (MM-CKA). Treatment of MM-CKA with guanidine hydrochloride released the unbound subunit to yield the matrix-bound monomer (M-CKB). M-CKB recombined with dissociated MM-CK soluble subunits to reconstitute a matrix-bound dimer (MM-CKC). M-CKB also associated with dissociated subunits of BB-CK from crude extracts of rabbit brain and of arginine kinase from sea cucumber muscle (MM-AK) to form the matrix-bound heterohybrids MB-CKC and M-CK/M-AKC, respectively. Guanidine hydrochloride gradient elution studies showed that MM-CKA, MM-CKC and MB-CKC were all dissociated at the same concentration of the denaturant (0.96 M), while the M-CK/M-AKC heterohybrid was less stable, dissociating at 0.5 M. The specific interaction between subunits of echinoderm and mammalian phosphagen kinases to form a hybrid enzyme of dual substrate specificity supports the view that these enzymes had a common evolutionary origin.

Animals↗
PubMed2006

Presence/absence polymorphism for alternative pathogenicity islands in Pseudomonas viridiflava, a pathogen of Arabidopsis.

The contribution of arms race dynamics to plant-pathogen coevolution has been called into question by the presence of balanced polymorphisms in resistance genes of Arabidopsis thaliana, but less is known about the pathogen side of the interaction. Here we investigate structural polymorphism in pathogenicity islands (PAIs) in Pseudomonas viridiflava, a prevalent bacterial pathogen of A. thaliana. PAIs encode the type III secretion system along with its effectors and are essential for pathogen recognition in plants. P. viridiflava harbors two structurally distinct and highly diverged PAI paralogs (T- and S-PAI) that are integrated in different chromosome locations in the P. viridiflava genome. Both PAIs are segregating as presence/absence polymorphisms such that only one PAI ([T-PAI, nablaS-PAI] and [nablaT-PAI, S-PAI]) is present in any individual cell. A worldwide population survey identified no isolate with neither or both PAI. T-PAI and S-PAI genotypes exhibit virulence differences and a host-specificity tradeoff. Orthologs of each PAI can be found in conserved syntenic locations in other Pseudomonas species, indicating vertical phylogenetic transmission in this genus. Molecular evolutionary analysis of PAI sequences also argues against "recent" horizontal transfer. Spikes in nucleotide divergence in flanking regions of PAI and nabla-PAI alleles suggest that the dual PAI polymorphism has been maintained in this species under some form of balancing selection. Virulence differences and host specificities are hypothesized to be responsible for the maintenance of the dual PAI system in this bacterial pathogen.

Arabidopsis↗
PubMed2005

Dual multiple change-point model leads to more accurate recombination detection.

MOTIVATION: We introduce a dual multiple change-point (MCP) model for recombination detection among aligned nucleotide sequences. The dual MCP model is an extension of the model introduced previously by Suchard and co-workers. In the original single MCP model, one change-point process is used to model spatial phylogenetic variation. Here, we show that using two change-point processes, one for spatial variation of tree topologies and the other for spatial variation of substitution process parameters, increases recombination detection accuracy. Statistical analysis is done in a Bayesian framework using reversible jump Markov chain Monte Carlo sampling to approximate the joint posterior distribution of all model parameters. RESULTS: We use primate mitochondrial DNA data with simulated recombination break-points at specific locations to compare the two models. We also analyze two real HIV sequences to identify recombination break-points using the dual MCP model.

Algorithms↗
PubMed2002

Tacrolimus and low-dose steroid immunosuppression preserves bone mass after renal transplantation.

Bone loss, a recognized complication of renal transplantation (TP), is mainly attributed to steroids. The effect of other immunosuppressive agents on patients' bone mass is difficult to distinguish from that of steroids. In this study, we evaluate the evolution of bone mass density over the first 12 months following renal TP in two groups of patients given either low-dose steroids with tacrolimus ( n=7) or normal-dose steroids and cyclosporine ( n=19). Bone mineral density (BMD) of the lumbar spine, total hip, and hip subregions and total-body bone mineral content (BMC) were measured by dual-energy X-ray absorptiometry within the first 15 days, and 1 year after TP. Biological markers of bone turnover (serum calcium, phosphate, total alkaline phosphatase activity, intact parathyroid hormone, bone-specific alkaline phosphatase, calcitriol, and urinary pyridinolines) were regularly measured during follow-up. After TP, renal function improved rapidly in all patients. One year after TP, bone mass had decreased significantly in the cyclosporine group in all investigated sites. By contrast it had increased in the tacrolimus group. In order to compare the evolution of bone mass in patients given similar amounts of steroids, the cyclosporine group was subdivided in tertiles according to the 1-year cumulative oral intake of prednisolone. A significant bone loss was still observed in the low-steroid cyclosporine subgroup but not in the tacrolimus group, despite the similar steroids intake (3.5+/-0.5 g and 2.7+/-1 g, respectively). Bone gain in the tacrolimus group occurred despite a previous longer dialysis duration and a higher number of postmenopausal women who were not receiving hormone substitutes. Long-term evaluation of bone density (3-5 years post-TP) confirmed the bone gain in the tacrolimus patients. Interestingly, the profile of the biological markers of bone turnover appeared better in patients prescribed tacrolimus than in those given cyclosporine, though the differences did not reach statistical significance. Weconclude that tacrolimus associated with low-dose steroids might better preserve bone mass after renal TP than cyclosporine and normal doses of steroids.

Absorptiometry, Photon↗
PubMed2001

The evolution of controlled multitasked gene networks: the role of introns and other noncoding RNAs in the development of complex organisms.

Eukaryotic phenotypic diversity arises from multitasking of a core proteome of limited size. Multitasking is routine in computers, as well as in other sophisticated information systems, and requires multiple inputs and outputs to control and integrate network activity. Higher eukaryotes have a mosaic gene structure with a dual output, mRNA (protein-coding) sequences and introns, which are released from the pre-mRNA by posttranscriptional processing. Introns have been enormously successful as a class of sequences and comprise up to 95% of the primary transcripts of protein-coding genes in mammals. In addition, many other transcripts (perhaps more than half) do not encode proteins at all, but appear both to be developmentally regulated and to have genetic function. We suggest that these RNAs (eRNAs) have evolved to function as endogenous network control molecules which enable direct gene-gene communication and multitasking of eukaryotic genomes. Analysis of a range of complex genetic phenomena in which RNA is involved or implicated, including co-suppression, transgene silencing, RNA interference, imprinting, methylation, and transvection, suggests that a higher-order regulatory system based on RNA signals operates in the higher eukaryotes and involves chromatin remodeling as well as other RNA-DNA, RNA-RNA, and RNA-protein interactions. The evolution of densely connected gene networks would be expected to result in a relatively stable core proteome due to the multiple reuse of components, implying that cellular differentiation and phenotypic variation in the higher eukaryotes results primarily from variation in the control architecture. Thus, network integration and multitasking using trans-acting RNA molecules produced in parallel with protein-coding sequences may underpin both the evolution of developmentally sophisticated multicellular organisms and the rapid expansion of phenotypic complexity into uncontested environments such as those initiated in the Cambrian radiation and those seen after major extinction events.

Animals↗
PubMed1995

A hierarchical molecular phylogeny within the genus Daphnia.

The nucleotide sequences of two mitochondrial DNA regions were used to determine phylogenetic relationships in the genus Daphnia (water fleas), a group for which systematics are historically unstable. A portion of the small ribosomal RNA was used to reconstruct higher-level relationships among species, while a portion of the more rapidly evolving control region was used to reconstruct lower-level relationships among populations. Two unexpected results were obtained. First, the subgeneric status of Ctenodaphnia falls into uncertainty on the basis of the failure of the 12S rRNA sequences to support these species as comprising an outgroup to the remainder of Daphnia species. Second, the high similarity of 12S rRNA sequences of Daphnia pulex and Daphnia pulicaria samples, coupled with the dual paraphyly of these samples as reconstructed from control-region analysis, suggests that they are two clonotype constellations within the same species complex. A combination of a variety of ecological influences has apparently resulted in the evolution of sets of Daphnia genotypes that are genetically cohesive despite their phenotypic divergence.

Alleles↗
PubMed2000

Longitudinal study of bone density and its determinants in women in peri- or early menopause.

The evolution of bone mass across menopause as well as the factors related to bone loss were studied in 141 women already assessed 10 years ago while in premenopause. Bone density of the lumbar spine was measured by dual photon absorptiometry. Nutrient intakes, lifestyle habits, data on menopause, and hormone replacement therapy were obtained by questionnaires. Present bone density was related significantly to past and current calcium intake, current vitamin D intake, and leisure physical activity level, as well as bone density measured in premenopause. Average bone loss was related to time elapsed without estrogens, age at menopause and present age, as well as serum levels of osteocalcin and alkaline phosphatase (ALP). Bone loss was inversely related to calcium and vitamin D intakes and to serum 25-OH vitamin D (25OHD) levels. By multiple regression analyses, only bone density in premenopause, time without estrogens, weight, vitamin D intake, and serum ALP levels remained as independent predictors of present bone mass or bone loss. This study emphasizes the importance of building a good bone mass before menopause, of having adequate vitamin D intake, and of beginning estrogen replacement therapy as soon as possible to minimize bone loss in the first years of menopause.

Adult↗
PubMed2004

Single-cell C(4) photosynthesis versus the dual-cell (Kranz) paradigm.

The efficiency of photosynthetic carbon assimilation in higher plants faces significant limitations due to the oxygenase activity of the enzyme Rubisco, particularly under warmer temperatures or water stress. A drop in atmospheric CO(2) and rise in O(2) as early as 300 mya provided selective pressure for the evolution of mechanisms to concentrate CO(2) around Rubisco in order to minimize oxygenase activity and the resultant loss of carbon through photorespiration. It is well established that a carbon-concentrating mechanism occurs in some terrestrial plants through the process of C(4) photosynthesis. These plants are characterized as having Kranz-type leaf anatomy, with two structurally and biochemically specialized photosynthetic cell types, mesophyll and bundle sheath, that function coordinately in carbon assimilation. C(4) photosynthesis has evolved independently many times with great diversity in forms of Kranz anatomy, structure of dimorphic chloroplasts, and biochemistry of the C(4) cycle. The most dramatic variants of C(4) terrestrial plants were discovered recently in two species, Bienertia cycloptera and Borszczowia aralocaspica (family Chenopodiaceae); each has novel compartmentation to accomplish C(4) photosynthesis within a single chlorenchyma cell. This review discusses the amazing diversity in C(4) systems, how the essential features of C(4) are accomplished in single-cell versus Kranz-type C(4) plants, and speculates on why single-cell C(4) plants evolved.

Chloroplasts↗
PubMed1989

Detection of hepatitis B surface antigen (HBsAg) in peripheral blood mononuclear cells of patients with acute and chronic active hepatitis B.

Seventy five patients with acute and chronic active hepatitis (CAH) were studied by indirect immunofluorescence with monoclonal antibodies for the presence of hepatitis B surface antigen (HBsAg) on peripheral blood mononuclear cells (PBMC). The viral surface antigen was detected in the PBMC of all the patients with hepatitis B virus (HBV)-induced CAH and in acute patients with more than 2 months of evolution. No HBsAg was detected in the samples obtained from 12 normal controls or from 14 non-A, non-B CAH patients. Analysis of PBMC subsets revealed that HBsAg was present in non-T cells; dual fluorescence studies showed HBsAg on surface Ig-positive lymphocytes. The binding of anti-HBs monoclonal antibodies was higher than that of a goat anti-HBs serum, and the highest reactivity was observed with an antibody against the pre-S(2)-region sequence. Both HBsAg and hepatitis B core antigen (HBcAg) were also detected in lysates of PBMC by dot blot analysis.

Acute Disease↗
PubMed1996

The elusive role of the N-terminal extension of beta A3- and beta A1-crystallin.

beta-Crystallins are structural lens proteins with a conserved two-domain structure and variable N- and C-terminal extensions. These extensions are assumed to be involved in quaternary interactions within the beta-crystallin oligomers or with other lens proteins. Therefore, the production of beta A3- and beta A1-crystallin from the single beta A3/A1 mRNA by dual translation initiation is of interest. These crystallins are identical, except that beta A1 has a much shorter N-terminal extension that beta A3. This rare mechanism has been conserved for over 250 million years during the evolution of the beta A3/A1 gene, suggesting that the generation of different N-terminal extensions confers a selective advantage. We therefore compared the stability and association behaviour of recombinant beta A3- and beta A1-crystallin. Both proteins are equally stable in urea- and pH-induced denaturation experiments. Gel filtration and analytical ultracentrifugation established that beta A3 and beta A1 both form homodimers. In the water-soluble proteins of bovine lens, beta A3 and beta A1 are present in the same molecular weight fractions, indicating that they oligomerize equally with other beta-crystallins. 1H-NMR spectroscopy showed that residues Met1 to Asn22 of the N-terminal extension of beta A3 have great flexibility and are solvent exposed, excluding them from protein interactions in the homodimer. These results indicate that the different N-terminal extensions of beta A3 and beta A1 do not affect their homo- or heteromeric interactions.

Amino Acid Sequence↗