Optimal blocking screw placement for retrograde IM nail fixation of distal femur fracture: a standardized biomechanical study of "osteoporotic" synthetic bone.

PURPOSE: Intramedullary (IM) nail use for metaphyseal fracture management is problematic in long bones like the femur because the larger medullary cavity allows increased fracture motion and potentially increased implant failure and malunion/nonunion risk; Achieving effective distal femur fracture fixation is even more difficult in osteoporotic bone. Blocking screws to control IM nail movement are known to be effective for tibia fracture management. Few studies have evaluated IM nail and blocking screw use efficacy for distal femur fracture fixation in osteoporotic bone. METHODS: This study used an osteoporosis simulation synthetic bone model to evaluate retrograde IM nail fixation of a standardized non-comminuted, extra-articular distal femur fracture with and without blocking screws. The hypothesis was that use of one or two blocking screws would increase IM nail fixation stability as evidenced by greater peak IM nail load and lesser movement. A servohydraulic device under displacement control collected loading force versus movement deflection data. Shapiro-Wilk tests confirmed data normality. One-way analysis of variance and Tukey post hoc tests were used to compare condition specific loading force and movement differences. RESULT: In the coronal plane, blocking screw conditions displayed greater loading ranges (38.3 ± 2 vs. 19.1 ± 2 N, 100.5% difference) (p < 0.0001) and lesser movement (2.0 ± 0.3 vs. 6.86 ± 0.4 mm, 243% difference) (p < 0.0001). In the sagittal plane, the two blocking screw condition displayed a significantly greater loading magnitude (29.9 ± 6 vs. 20.8 ± 2.3 N, 43.8% difference) than the identical control condition without blocking screws (p = 0.018); however, movements were comparable (p = 0.82). Long-axis rotational loading failed to reveal load magnitude differences (p = 0.28); however, two different blocking screw conditions displayed decreased movement (1.32 ± 0.2 vs. 2.05 ± 0.3 mm, 53.8% difference) compared to other conditions (p ≤ 0.018). CONCLUSIONS: Use of one or two blocking screws on the medial and lateral sides of the IM nail decreased coronal plane movement in the intramedullary canal. Combining retrograde IM nail implantation with blocking screws reduced medial-lateral IM nail movement and increased fracture stability. These characteristics may help prevent fixation failure, malunion, and even nonunion in patients with a distal femur fracture in osteoporotic bone.

Non-steroidal anti-inflammatory drug prescriptions in hospital inpatients: are we assessing the risks?

AIM: To determine non-steroidal anti-inflammatory drug (NSAID) prescribing practices in a tertiary referral hospital. METHODS: A single time-point audit of drug kardexes and clinical notes of n = 388 patients on 2 July 2008 was carried out assessing demographics, gastrointestinal and coronary heart disease risk factors, renal function and co-prescribed medications. RESULTS: Fifty-seven of 388 (14.7%) hospital patients were on NSAIDs. Forty-nine were prescribed NSAID after admission. Nineteen (32.2%) were on regular NSAID (11/19 on PPI) and 38 patients were on PRN NSAID (12/38 on PPI). Seventeen of 49 patients were on other medications associated with gastrointestinal bleeding (10/17 were on PPI). Nineteen patients (33.3%) were >60 years. Eight patients had three or four risk factors for gastrointestinal bleeding; six were on PPI. Thirteen patients had two risks; 7 were on PPI. Six of 19 patients with one risk factor were on PPI. 40.3% had stage 2/3 chronic kidney disease. 35.1% had ischaemic heart disease. CONCLUSIONS: NSAIDs and PPIs are often prescribed inappropriately.

The effect of Echinorhynchus borealis (Acanthocephala) infection on the anti-predator behavior of a benthic amphipod.

In benthic habitats, predators can generally not be detected visually, so olfaction may be particularly important for inducing anti-predation behaviors in prey organisms. Manipulative parasites infecting benthic hosts could suppress these responses so as to increase the probability of predation and thus trophic transmission. We studied how infection with the acanthocephalan Echinorhynchus borealis affects the response of the benthic amphipod Pallasea quadrispinosa to water conditioned by burbot (Lota lota), the parasite's definitive host. In normal lake water, refuge use by infected and uninfected amphipods was similar, but when exposed to burbot-conditioned water, uninfected amphipods spent much more time hiding than infected amphipods. Thus, rather than affecting ambient hiding behavior, E. borealis infection seems to alter host response to a predator. A group of amphipods sampled from a postglacial spring that is devoid of fish predators exhibited only a weak response to burbot-conditioned water, perhaps suggesting these anti-predator behaviors are costly to maintain. The hiding behavior of spring and infected amphipods was very similar. If the reduced refuge use by the spring amphipods reflects adaptation to a predator-free environment, this indicates that E. borealis severely weakens its host's anti-predator behavior. Presumably this increases the likelihood of parasite transmission.

Characterization of the human secreted phosphoprotein 24 gene (SPP2) and comparison of the protein sequence in nine species.

Secreted phosphoprotein 24 (spp24) is a member of the cystatin superfamily, which was first identified in cattle as a minor component of cortical bone and subsequently has been identified as a component of the fetuin-mineral complex. We have localized the human SPP2 gene, which encodes spp24 to chromosome 2q37.1, determined its structure and mapped the start of transcription in liver. There is no CAAT or TATA box in the promoter region but potential transcription factor (TF)-binding sites have been identified. The gene comprises eight exons spread over a region of approximately 27 kb with the cystatin-like region of spp24 encoded by four exons, rather than the three-exon structure typical of the genes encoding the archetypal cystatins. A rare single amino acid polymorphism (p.S38F) has been identified within the mature protein and its significance has been assessed by comparing the sequence of human spp24 with that of eight other species.

Large-scale cDNA analysis reveals phased gene expression patterns during preimplantation mouse development.

Little is known about gene action in the preimplantation events that initiate mammalian development. Based on cDNA collections made from each stage from egg to blastocyst, 25438 3'-ESTs were derived, and represent 9718 genes, half of them novel. Thus, a considerable fraction of mammalian genes is dedicated to embryonic expression. This study reveals profound changes in gene expression that include the transient induction of transcripts at each stage. These results raise the possibility that development is driven by the action of a series of stage-specific expressed genes. The new genes, 798 of them placed on the mouse genetic map, provide entry points for analyses of human and mouse developmental disorders.

Nutritionally enhanced cereals: A sustainable foundation for a balanced diet.

Three nutrients, iron, zinc and pro-vitamin A, are widely deficient in humans, especially among low socioeconomic groups in developing countries, but they remain significant concerns in industrialized countries as well. Cereals provide the majority of the intake of these nutrients in low-income families. Moreover, these three nutrients may interact synergistically in absorption and function to such an extent that there are potentially huge advantages in providing all three together in the one staple food. Because of this, they may be more bioavailable to deficient individuals than current thinking allows. To do so would provide a sound basis on which to build a better balanced diet for nutritionally compromised individuals. Genetic variation in nutrient composition exists in cereals and can be exploited in conventional breeding programmes and through gene technology. Cultural techniques, including fertiliser technology and organic farming, have also impacted upon the nutrient composition of cereals. Human iron and zinc intake can be doubled at least, and essential carotenoid intakes can be increased dramatically. Preliminary feeding trials with nutrient-dense grains have been encouraging. Moreover, nutrient-dense seeds also produce more vigorous seedlings and higher grain yield in soils where these nutrients are poorly available, so that to a significant extent agronomic and health objectives coincide. New varieties are rapidly adopted, especially where there are yield advantages, ensuring maximum impact without new inputs. This approach is potentially more sustainable than fortification and supplementation programmes because intake is continuous, which is especially important for zinc because it is needed almost daily.

Two novel mouse genes--Nubp2, mapped to the t-complex on chromosome 17, and Nubp1, mapped to chromosome 16--establish a new gene family of nucleotide-binding proteins in eukaryotes.

Two novel mouse genes and one novel human gene that define distinctive eukaryotic nucleotide-binding proteins (NUBP) and are related to the mrp gene of prokaryotes are characterized. Phylogenetic analyses of the genes, encoding a short form (Nubp2) and a long form (Nubp1) of NUBP, clearly establish them as a new NUBP/MRP gene family that is well conserved throughout phylogeny. In addition to conserved ATP/GTP-binding motifs A (P-loop) and A', members of this family share at least two highly conserved sequence motifs, NUBP/MRP motifs alpha and beta. Only one type of NUBP/MRP gene has been observed thus far in prokaryotes, but there are two types in eukaryotes. One group includes mouse Nubp1, human NBP, yeast NBP35, and Caenorhabditis elegans F10G8.6 and is characterized by a unique N-terminal sequence with four cysteine residues that is lacking in the other group, which includes mouse Nubp2, human NUBP2, and yeast YIA3w. Northern blot analyses of the two mouse genes show distinctive patterns consistent with this classification. Mouse Nubp2 is mapped to the t-complex region of mouse Chromosome 17, whereas Nubp1 is mapped to the proximal region of mouse Chromosome 16. Interestingly, both regions are syntenic with human chromosome 16p13.1-p13.3, suggesting that a chromosomal breakage between Nubp2 and Nubp1 probably occurred during the evolution of mouse chromosomes.

Electrostatic interactions during acidic phospholipid reactivation of DnaA protein, the Escherichia coli initiator of chromosomal replication.

The initiation of Escherichia coli chromosomal replication by DnaA protein is strongly influenced by the tight binding of the nucleotides ATP and ADP. Anionic phospholipids in a fluid bilayer promote the conversion of inactive ADP-DnaA protein to replicatively active ATP-DnaA protein in vitro, and thus likely play a key role in regulating DnaA activity. Previous studies have revealed that, during this reactivation, a specific region of DnaA protein inserts into the hydrophobic portion of the lipid bilayer in an acidic phospholipid-dependent manner. To elucidate the requirement for acidic phospholipids in the reactivation process, the contribution of electrostatic forces in the interaction of DnaA and lipid was examined. DnaA-lipid binding required anionic phospholipids, and DnaA-lipid binding as well as lipid-mediated release of DnaA-bound nucleotide were inhibited by increased ionic strength, suggesting the involvement of electrostatic interactions in these processes. As the vesicular content of acidic phospholipids was increased, both nucleotide release and DnaA-lipid binding increased in a linear, parallel manner. Given that DnaA-membrane binding, the insertion of DnaA into the membrane, and the consequent nucleotide release all require anionic phospholipids, the acidic headgroup may be necessary to recruit DnaA protein to the membrane for insertion and subsequent reactivation for replication.

Genome-wide mapping of unselected transcripts from extraembryonic tissue of 7.5-day mouse embryos reveals enrichment in the t-complex and under-representation on the X chromosome.

Mammalian embryos can only survive if they attach to the uterus (implantation) and establish proper maternal-fetal interactions. To understand this complex implantation pathway, we have initiated genomic analysis with a systematic study of the cohort of genes expressed in extraembryonic cells that are derived from the conceptus and play a major role in this process. A total of 2103 cDNAs from the extraembryonic portion of 7.5-day post-conception mouse embryos yielded 3186 expressed sequence tags, approximately 40% of which were novel to the sequence databases. Furthermore, when 155 of the cDNA clones with no homology to previously detected genes were genetically mapped, apparent clustering of these expressed genes was detected in subregions of chromosomes 2, 7, 9 and 17, with 6.5% of the observed genes localized in the t-complex region of chromosome 17, which represents only approximately 1.5% of the mouse genome. In contrast, X-linked genes were under-represented. Semi-quantitative RT-PCR analyses of the mapped genes demonstrated that one third of the genes were expressed solely in extraembryonic tissue and an additional one third of the genes were expressed predominantly in the extraembryonic tissues. The over-representation of extraembryonic-expressed genes in dosage-sensitive autosomal imprinted regions and under-representation on the dosage-compensated X chromosome may reflect a need for tight quantitative control of expression during development.

LAT: the ZAP-70 tyrosine kinase substrate that links T cell receptor to cellular activation.

Despite extensive study, several of the major components involved in T cell receptor-mediated signaling remain unidentified. Here we report the cloning of the cDNA for a highly tyrosine-phosphorylated 36-38 kDa protein, previously characterized by its association with Grb2, phospholipase C-gamma1, and the p85 subunit of phosphoinositide 3-kinase. Deduced amino acid sequence identifies a novel integral membrane protein containing multiple potential tyrosine phosphorylation sites. We show that this protein is phosphorylated by ZAP-70/Syk protein tyrosine kinases leading to recruitment of multiple signaling molecules. Its function is demonstrated by inhibition of T cell activation following overexpression of a mutant form lacking critical tyrosine residues. Therefore, we propose to name the molecule LAT-linker for activation of T cells.

Membrane-mediated release of nucleotide from an initiator of chromosomal replication, Escherichia coli DnaA, occurs with insertion of a distinct region of the protein into the lipid bilayer.

DnaA protein, the initiator protein of E. coli chromosomal replication, can be rejuvenated from an inactive ADP form to active ATP-DnaA protein by acidic phospholipids in a fluid bilayer. Cross-linking studies with the photoactivable phospholipid analog 1-O-hexadecanoyl-2-O-[9-[[[2-[125I]iodo-4-(trifluoromethyl-3H- diazirin -3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine reveal insertion of DnaA protein into the hydrophobic region of the bilayer; this insertion is accompanied by membrane-mediated dissociation of the tightly bound allosteric nucleotides ADP and ATP. Photolabeling of DnaA protein occurred with membrane properties that resembled those needed for reactivation of ADP-DnaA protein; efficient labeling of DnaA protein was observed only when the lipid analog was incorporated into anionic vesicles and the temperature during treatment was above the gel to liquid crystalline phase transition. Predominant hydrophobic photolabeling was localized within a single region of DnaA protein, a region that contains putative amphipathic helices and has been shown to contain information essential for functional interaction with membranes.

ZBP-89, a Krüppel-like zinc finger protein, inhibits epidermal growth factor induction of the gastrin promoter.

We have shown previously that a GC-rich element (GGGGCGGGGTGGGGGG) conferring epidermal growth factor (EGF) responsiveness to the human gastrin promoter binds Sp1 and additional undefined complexes. A rat GH4 cell line expression library was screened by using a multimer of the gastrin EGF response element, and three overlapping cDNA clones were identified. The full-length rat cDNA encoded an 89-kDa zinc finger protein (ZBP-89) that was 89% identical to a 49-kDa human factor, ht(beta), that binds a GTGGG/CACCC element in T-cell receptor promoters. The conservation of amino acids between the zinc fingers indicates that ZBP-89 is a member of the C2H2 zinc finger family subclass typified by the Drosophila Krüppel protein. ZBP-89 is ubiquitously expressed in normal adult tissues. It binds specifically to the gastrin EGF response element and inhibits EGF induction of the gastrin promoter. Collectively, these results demonstrate that ZBP-89 functions as a repressor of basal and inducible expression of the gastrin gene.

Synthesis and release of hyaluronic acid by Swiss 3T3 fibroblasts.

Hyaluronic acid (HA) and its synthesis were studied in intact Swiss 3T3 mouse fibroblasts and isolated membranes. HA chains in culture medium, attached to cells and in isolated membranes, were determined to possess average M(r) values of 5.2 x 10(6), 1.8 x 10(6) and 0.14 x 10(6) respectively. Log cells were determined to possess 680,000 HA molecules/cell, and to release 120,000 HA chains/h. The time required for intact cells to synthesize and release a complete HA chain was approximately 4 h, with elongation proceeding at a rate of 57 dimers/min. The amount of cell-associated HA of various cell populations correlated strongly with their rate of HA release into culture media and with the HA synthetase activity determined for their membranes. Prevention of protein synthesis with cycloheximide decreased the rate of HA synthesis of log cells and HA synthetase activity of isolated membranes by 50% within 2-3 h. Because of the similarity between the biological lifetime of HA synthetase and the time required to synthesize a HA chain, we propose a model where each synthetase makes only one HA chain; after synthesis of a complete HA chain, HA synthetase activity is terminated as its HA chain is released from the cell.

Pulmonary hypertension predicts mortality and morbidity in patients with dilated cardiomyopathy.

OBJECTIVE: To ascertain whether pulmonary hypertension, as assessed noninvasively by continuous-wave Doppler of tricuspid regurgitation, can be an important independent factor in the prognosis of patients with ischemic or idiopathic dilated cardiomyopathy. DESIGN: Cohort study of consecutive patients with dilated cardiomyopathy in whom follow-up was obtained on all survivors for 28 months. SETTING: Outpatient cardiology private practice office in a tertiary care center. PATIENTS: Consecutive sample of 108 patients who presented for a scheduled office visit during a 15-month period. MEASUREMENTS: M-mode, two-dimensional, and Doppler echocardiographic examinations were done on all patients at entry into the study and on survivors 1 year later. All examinations included extensive pulsed- and continuous-wave Doppler evaluation for tricuspid regurgitation. MAIN OUTCOME MEASURES: Overall mortality, mortality due to myocardial failure, and hospitalization for congestive heart failure. RESULTS: Twenty-eight patients had a high velocity of tricuspid regurgitation (greater than 2.5 m/s), and 80 patients had a low velocity (less than or equal to 2.5 m/s). After 28 months of follow-up, the mortality rate was 57% in patients with a high velocity compared with 17% in patients with a low velocity (difference of 40%, 95% CI, 20% to 60%). Hospitalization for congestive heart failure occurred in 75% and 26% of patients, respectively (difference of 49%, CI, 30% to 68%). Eighty-nine percent of patients with a high velocity either died or were hospitalized compared with only 32% of patients with a low velocity (difference of 57%, CI, 42% to 72%). The peak velocity of tricuspid regurgitation was the only prognostic variable selected using stepwise logistic regression models for the three outcome events. CONCLUSION: Noninvasive assessment of pulmonary hypertension using continuous-wave Doppler of tricuspid regurgitation can predict morbidity and mortality in patients with ischemic or idiopathic dilated cardiomyopathy.

Left ventricular thrombus in the absence of detectable heart disease.

A woman presented with acute left leg pain requiring urgent left femoral embolectomy. Echocardiography showed a large, pedunculated left ventricular mass, but no additional cardiac abnormality. Clinical evaluation including cardiac catheterization and open heart surgery demonstrated no cardiac pathologic findings. At surgery, a large thrombus was removed from the left ventricle. We suggest that all patients with arterial embolic disease have echocardiography, even if heart disease is not suspected.

Niveles de hemoglobina y cirugia coronaria: I. Relacion entre hemoglobina arterial coronaria y flujo coronario / Hemoglobin levels and coronary surgery: I. Relationship between coronary arterial hemoglobin and coronary flow

Hasta el momento no se ha demostrado que el flujo coronario, aumentado en casos de anemia, sea un mecanismo de defensa contra anoxia miocardiaca y no simplemente una respuesta a las demandas energeticas y mecanicas del gasto cardiaco elevado que estos pacientes desarrollan en esta situacion clinica. En el laboratorio de cirugia experimental del Hospital Freeman (Newcastle upon Tyne, Inglaterra), se disminuyo en forma abrupta la concentracion de hemoglobina en sangre que perfundia las coronarias de perros normales. Posteriormente se midieron en forma individual el volumen de sangre y la concentracion de hemoglobina del seno coronario a intervalos de 1 minuto y por espacio de cinco minutos, es decir en un intervalo de tiempo seguro, antes que el gasto cardiaco se elevara a consecuencia de la anemia generalizada en el animal de experimentacion, permitiendo asi apreciar si en realidad el flujo coronario efectivamente aumentaba en relacion con la disminucion de hemoglobina miocardica. Se encontro entonces que el flujo coronario aumento a medida que la concentracion de hemoglobina disminuia, siendo el coeficiente de correlacion de -0,5629, lo cual fue significativo (p<0,001). El resultado de este aumento compensatorio fue en tal medida efectivo que no encontramos cambio significativo en la presion parcial de oxigeno del seno coronario. Es decir, el mecanismo compensatorio fue aumentando el flujo sanguineo sin encrementar la extraccion de oxigeno por las celulas miocardicas...

R-wave amplitude responses to rapid atrial pacing: a marker for myocardial ischemia.

Atrial pacing-induced changes in the sum of R-wave amplitude were measured in leads V5, X, Y, and Z at rates of 100 bpm (phase I), 150 bpm (phase II), and immediately after pacing (phase III) in 33 patients undergoing cardiac catheterization for evaluation of chest pain. Seventeen (51%) patients showed evidence of ischemia during atrial pacing (typical anginal pain and/or at least a 1 mm ST-segment depression) and 16 (49%) showed no evidence of ischemia. Mean R-wave amplitude changes from baseline in the ischemic patients were: phase I: -8% (p = not significant), phase II: +3% (p = not significant), and phase III: +13% (p less than 0.01); and in nonischemic patients: phase I: -11% (p less than 0.02), phase II: -18% (p less than 0.01), and phase III: +2% (p = not significant). These two distinct patterns of R-wave amplitude changes were highly sensitive (85%), specific (92%), and predictive (92%) for identifying patients with myocardial ischemia but did not correlate (p = not significant) with either the angiographically determined extent of coronary artery obstructive disease (CAD), resting left ventricular function, or the dynamic, atrial pacing-induced changes in left ventricular dimensions determined by M-mode and two-dimensional echocardiography. Thus, R-wave amplitude changes induced by atrial pacing can be used to identify patients with myocardial ischemia independent of coronary anatomy or resting left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)