Developmental plasticity is bound by pluripotency and the Fgf and Wnt signaling pathways

Plasticity is a well-known feature of mammalian development, and yet very little is known about its underlying mechanism. Here, we establish a model system to examine the extent and limitations of developmental plasticity in living mouse embryos. We show that halved embryos follow the same strict clock of developmental transitions as intact embryos, but their potential is not equal. We have determined that unless a minimum of four pluripotent cells is established before implantation, development will arrest. This failure can be rescued by modulating Fgf and Wnt signaling to enhance pluripotent cell number, allowing the generation of monozygotic twins, which is an otherwise rare phenomenon. Knowledge of the minimum pluripotent-cell number required for development to birth, as well as the different potentials of blastomeres, allowed us to establish a protocol for splitting an embryo into one part that develops to adulthood and another that provides embryonic stem cells for that individual.

Dynamics of anterior-posterior axis formation in the developing mouse embryo

The development of an anterior-posterior (AP) polarity is a crucial process that in the mouse has been very difficult to analyse, because it takes place as the embryo implants within the mother. To overcome this obstacle, we have established an in-vitro culture system that allows us to follow the step-wise development of anterior visceral endoderm (AVE), critical for establishing AP polarity. Here we use this system to show that the AVE originates in the implanting blastocyst, but that additional cells subsequently acquire AVE characteristics. These 'older' and 'younger' AVE domains coalesce as the egg cylinder emerges from the blastocyst structure. Importantly, we show that AVE migration is led by cells expressing the highest levels of AVE marker, highlighting that asymmetry within the AVE domain dictates the direction of its migration. Ablation of such leading cells prevents AVE migration, suggesting that these cells are important for correct establishment of the AP axis.

Formation of distinct cell types in the mouse blastocyst

Early development of the mouse comprises a sequence of cell fate decisions in which cells are guided along a pathway of restricted potential and increasing specialisation. The first choice faced by cells of the embryo is whether to become trophectoderm (TE) or inner cell mass (ICM); TE is an extra-embryonic tissue which will form the embryonic portion of the placenta, whilst ICM gives rise to cells responsible for generating the foetus. In the second cell fate decision, the ICM is further refined into pluripotent cells forming the future body of the embryo, epiblast (EPI) and extra-embryonic primitive endoderm (PE), a tissue essential for patterning the embryo and establishing the developmental circulation. Understanding this early lineage segregation is critical for informing attempts to capture pluripotency and direct cell fate in vitro. Unlike the predictability of nonmammalian cell fate, development of the mouse embryo retains the flexibility to adapt to changing circumstances during development. Here we describe these first cell fate decisions, how they can be biased whilst maintaining flexibility and, finally, some of the molecular circuitry underlying early fate choice.

Similar withdrawal severity in adolescents and adults in a rat model of alcohol dependence

Alcohol use during adolescence leads to increased risk of developing an alcohol use disorder (AUD) during adulthood. Converging evidence suggests that this period of enhanced vulnerability for developing an AUD may be due to the adolescent's unique sensitivity and response to alcohol. Adolescent rats have been shown to be less sensitive to alcohol intoxication and withdrawal susceptibility; however, age differences in ethanol pharmacokinetics may underlie these effects. Therefore, this study investigated alcohol intoxication behavior and withdrawal severity using a modified Majchrowicz model of alcohol dependence that has been shown to result in similar blood ethanol concentrations (BECs) despite age differences. Adolescent (postnatal day, PND, 35) and adult rats (PND 70+) received ethanol according to this 4-day binge paradigm and were observed for withdrawal behavior for 17h. As expected, adolescents showed decreased sensitivity to alcohol-induced CNS depression as evidenced by significantly lower intoxication scores. Thus, adolescents received significantly more ethanol each day (12.3+/-0.1g/kg/day) than adults (9.2+/-0.2g/kg/day). Despite greater ethanol dosing in adolescent rats, both adolescent and adult groups had comparable peak BECs (344.5+/-10.2 and 338.5+/-7.8mg/dL, respectively). Strikingly, withdrawal severity was similar quantitatively and qualitatively between adolescent and adult rats. Further, this is the first time that withdrawal behavior has been reported for adolescent rats using this model of alcohol dependence. A second experiment confirmed the similarity in BECs at various time points across the binge. These results demonstrate that after consideration of ethanol pharmacokinetics between adults and adolescents by using a model that produces similar BECs, withdrawal severity is nearly identical. This study, in combination with previous reports on ethanol withdrawal in adolescents and adults, suggests only a BEC-dependent effect of ethanol on withdrawal severity regardless of age.

Making a firm decision: multifaceted regulation of cell fate in the early mouse embryo

The preimplantation mammalian embryo offers a striking opportunity to address the question of how and why apparently identical cells take on separate fates. Two cell fate decisions are taken before the embryo implants; these decisions set apart a group of pluripotent cells, progenitors for the future body, from the distinct extraembryonic lineages of trophectoderm and primitive endoderm. New molecular, cellular and developmental insights reveal the interplay of transcriptional regulation, epigenetic modifications, cell position and cell polarity in these two fate decisions in the mouse. We discuss how mechanisms proposed in previously distinct models might work in concert to progressively reinforce cell fate decisions through feedback loops.

Active cell movements coupled to positional induction are involved in lineage segregation in the mouse blastocyst

In the mouse blastocyst, some cells of the inner cell mass (ICM) develop into primitive endoderm (PE) at the surface, while deeper cells form the epiblast. It remained unclear whether the position of cells determines their fate, such that gene expression is adjusted to cell position, or if cells are pre-specified at random positions and then sort. We have tracked and characterised dynamics of all ICM cells from the early to late blastocyst stage. Time-lapse microscopy in H2B-EGFP embryos shows that a large proportion of ICM cells change position between the surface and deeper compartments. Most of this cell movement depends on actin and is associated with cell protrusions. We also find that while most cells are precursors for only one lineage, some give rise to both, indicating that lineage segregation is not complete in the early ICM. Finally, changing the expression levels of the PE marker Gata6 reveals that it is required in surface cells but not sufficient for the re-positioning of deeper cells. We provide evidence that Wnt9A, known to be expressed in the surface ICM, facilitates re-positioning of Gata6-expressing cells. Combining these experimental results with computer modelling suggests that PE formation involves both cell sorting movements and position-dependent induction.

Cancellous and cortical bone architecture and turnover at the iliac crest of postmenopausal osteoporotic women treated with parathyroid hormone 1-84

Treatment with parathyroid hormone [PTH(1-84)] increases lumbar spine bone mineral density and decreases vertebral fractures, but its effects on bone microarchitecture are unknown. We obtained iliac crest biopsies from postmenopausal osteoporotic women given placebo (n=8) or 100 microg PTH(1-84) for 18 (n=8) or 24 (n=7) months to assess cancellous and cortical bone formation and structure. At 18 months, cancellous bone volume (BV/TV) measured by microcomputed tomography and histomorphometry was 45-48% higher in subjects treated with PTH(1-84) versus placebo, a result of higher trabecular number (Tb.N) and thickness. The higher Tb.N appeared to result from intratrabecular tunneling. Connectivity density was higher and structure model index was lower, indicating a better connected and more plate-like trabecular architecture. Cancellous bone formation rate (BFR) was 2-fold higher in PTH(1-84)-treated subjects, primarily because of greater mineralizing surface. Osteoblast and osteoid surfaces were a nonsignificant 58% and 35%, respectively, higher with PTH(1-84) treatment. Osteoclast and eroded surface were unaffected by PTH(1-84). There were no effects of PTH(1-84) treatment on cortical thickness, or endocortical or periosteal BFR, but cortical porosity tended to be higher. Although cancellous BFR was lower at 24 than at 18 months, measures of cancellous and cortical bone structure were similar at both timepoints. The bone produced by PTH(1-84) had normal lamellar structure and mineralization with no abnormal histology. In conclusion, when compared with placebo, treatment of osteoporotic women with PTH(1-84) was associated with higher BV/TV and trabecular connectivity, with a more plate-like architecture, all consistent with the lower vertebral fracture incidence.

Parathyroid hormone(1-84) treatment of postmenopausal women with low bone mass receiving hormone replacement therapy

Treatment of postmenopausal osteoporosis (PMO) is based primarily on antiresorptive agents, including hormone replacement therapy (HT). To evaluate whether anabolic therapy together with HT provides additional benefits in the treatment of PMO, we evaluated the effects of parathyroid hormone (PTH) 1-84 in postmenopausal women with low bone mineral density (BMD) who were receiving chronic (> or =6 months) HT. Subjects were randomized to receive 100 microg PTH(1-84) or placebo injections daily for 24 months (n = 90/group). The primary efficacy outcome was change from baseline in lumbar spine BMD. Secondary end points included changes in hip and distal radius BMD, bone turnover markers, and fracture incidence. The study was terminated early following recommendations regarding HT for PMO. At 18 months, the mean increase in lumbar spine BMD was 7.9% for PTH(1-84) subjects vs. 1.5% for those receiving HT alone; between-group differences were significant at 6 months and persisted throughout the study. Lumbar spine BMD increased in 94% of women receiving PTH(1-84) compared to 59% for HT alone. Femoral neck BMD and bone turnover markers were significantly higher in PTH(1-84)-treated subjects, but the changes in total hip and distal radius BMD were not significant. PTH(1-84) treatment was generally well-tolerated, with hypercalciuria, hypercalcemia, nausea, vomiting, and dizziness reported more frequently in the HT + PTH(1-84) group. In conclusion, addition of PTH(1-84) to stable HT produced marked increases in lumbar spine BMD and may represent an additional approach to the treatment of PMO women receiving HT.

Tsukushi modulates Xnr2, FGF and BMP signaling: regulation of Xenopus germ layer formation

Background

Cell-cell communication is essential in tissue patterning. In early amphibian development, mesoderm is formed in the blastula-stage embryo through inductive interactions in which vegetal cells act on overlying equatorial cells. Members of the TGF-β family such as activin B, Vg1, derrière and Xenopus nodal-related proteins (Xnrs) are candidate mesoderm inducing factors, with further activity to induce endoderm of the vegetal region. TGF-β-like ligands, including BMP, are also responsible for patterning of germ layers. In addition, FGF signaling is essential for mesoderm formation whereas FGF signal inhibition has been implicated in endoderm induction. Clearly, several signaling pathways are coordinated to produce an appropriate developmental output; although intracellular crosstalk is known to integrate multiple pathways, relatively little is known about extracellular coordination.

Methodology/Principal Findings

Here, we show that Xenopus Tsukushi (X-TSK), a member of the secreted small leucine rich repeat proteoglycan (SLRP) family, is expressed in ectoderm, endoderm, and the organizer during early development. We have previously reported that X-TSK binds to and inhibits BMP signaling in cooperation with chordin. We now demonstrate two novel interactions: X-TSK binds to and inhibits signaling by FGF8b, in addition to binding to and enhancement of Xnr2 signaling. This signal integration by X-TSK at the extracellular level has an important role in germ layer formation and patterning. Vegetally localized X-TSK potentiates endoderm formation through coordination of BMP, FGF and Xnr2 signaling. In contrast, X-TSK inhibition of FGF-MAPK signaling blocks ventrolateral mesoderm formation, while BMP inhibition enhances organizer formation. These actions of X-TSK are reliant upon its expression in endoderm and dorsal mesoderm, with relative exclusion from ventrolateral mesoderm, in a pattern shaped by FGF signals.

Conclusions/Significance

Based on our observations, we propose a novel mechanism by which X-TSK refines the field of positional information by integration of multiple pathways in the extracellular space.

Effect of trophic status on the culturability and activity of bacteria from a range of lakes in the English Lake District

The bacterioplankton from a number of lakes that differed in nutrient status in the English Lake District was examined with a number of techniques for enumeration and activity assessment. Natural water samples showed a clear correlation between total counts and trophic status. Esterase activity measurements with Chemchrome B were able to distinguish high- and low-nutrient-status lakes, whereas tetrazolium salt (5-cyano-2,3-ditoyltetrazolium chloride) reduction, the direct viable count-cell elongation assay, and culturability measurements could not. Tetrazolium salt reduction and esterase activity measurements labeled a significant number of cells from water of all nutrient levels, whereas the direct viable count-cell elongation method was of use only in oligotrophic waters. Size fractionation of samples showed that the culturable cells were retained by the larger filters, especially in nutrient-rich waters. Esterase activity measurements also favored the larger cells. The differences observed between assays using water that differed in trophic status raise questions about the use of these tests as a definitive measure of viability.

Peripheral parenteral nutrition in a case of chyle leak following neck dissection

Chylothorax is an uncommon condition which is potentially life-threatening if untreated. The following case study of a 75-year-old man with chyle leak following surgery shows how prompt dietetic action prevented further compromise in immune function and nutritional status. Dietetic recommendation to minimize enteral intake rapidly stopped chyle flow and promoted wound closure. Peripheral parenteral nutrition (PPN) was administered in order to prevent malnutrition. There is limited literature available for evidence of best practice for cases of chyle leakage, however, this particular case demonstrates PPN should be considered despite the potential risks.

Identification of active methylotroph populations in an acidic forest soil by stable-isotope probing

Stable-isotope probing (SIP) is a culture-independent technique that enables the isolation of DNA from micro-organisms that are actively involved in a specific metabolic process. In this study, SIP was used to characterize the active methylotroph populations in forest soil (pH 3.5) microcosms that were exposed to (13)CH(3)OH or (13)CH(4). Distinct (13)C-labelled DNA ((13)C-DNA) fractions were resolved from total community DNA by CsCl density-gradient centrifugation. Analysis of 16S rDNA sequences amplified from the (13)C-DNA revealed that bacteria related to the genera Methylocella, Methylocapsa, Methylocystis and Rhodoblastus had assimilated the (13)C-labelled substrates, which suggested that moderately acidophilic methylotroph populations were active in the microcosms. Enrichments targeted towards the active proteobacterial CH(3)OH utilizers were successful, although none of these bacteria were isolated into pure culture. A parallel analysis of genes encoding the key enzymes methanol dehydrogenase and particulate methane monooxygenase reflected the 16S rDNA analysis, but unexpectedly revealed sequences related to the ammonia monooxygenase of ammonia-oxidizing bacteria (AOB) from the beta-subclass of the PROTEOBACTERIA: Analysis of AOB-selective 16S rDNA amplification products identified Nitrosomonas and Nitrosospira sequences in the (13)C-DNA fractions, suggesting certain AOB assimilated a significant proportion of (13)CO(2), possibly through a close physical and/or nutritional association with the active methylotrophs. Other sequences retrieved from the (13)C-DNA were related to the 16S rDNA sequences of members of the Acidobacterium division, the beta-Proteobacteria and the order Cytophagales, which implicated these bacteria in the assimilation of reduced one-carbon compounds or in the assimilation of the by-products of methylotrophic carbon metabolism. Results from the (13)CH(3)OH and (13)CH(4) SIP experiments thus provide a rational basis for further investigations into the ecology of methylotroph populations in situ.

Identification of the functionally active methanotroph population in a peat soil microcosm by stable-isotope probing

The active population of low-affinity methanotrophs in a peat soil microcosm was characterized by stable-isotope probing. "Heavy" (13)C-labeled DNA, produced after microbial growth on (13)CH(4), was separated from naturally abundant (12)C-DNA by cesium chloride density gradient centrifugation and used as a template for the PCR. Amplification products of 16S rRNA genes and pmoA, mxaF, and mmoX, which encode key enzymes in the CH(4) oxidation pathway, were analyzed. Sequences related to extant type I and type II methanotrophs were identified, indicating that these methanotrophs were active in peat exposed to 8% (vol/vol) CH(4). The (13)C-DNA libraries also contained clones that were related to beta-subclass Proteobacteria, suggesting that novel groups of bacteria may also be involved in CH(4) cycling in this soil.

A characterisation of long-term depression induced by metabotropic glutamate receptor activation in the rat hippocampus in vitro

1. In the CA1 region of hippocampal slices prepared from juvenile (12- to 18-day-old) rats, activation of group I metabotropic L-glutamate (mGlu) receptors by the specific agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) induces a form of long-term depression (LTD) of excitatory synaptic transmission. 2. We have used a variety of electrophysiological techniques applied to CA1 neurones in hippocampal slices and from pyramidal cells in dissociated hippocampal cultures to investigate the Ca2+ dependence and locus of expression of DHPG-induced LTD. 3. In patch-clamp experiments from hippocampal slices, bath application of DHPG induced a depression of synaptically evoked responses that persisted for the duration of the recording (up to 2 h after commencing washout of DHPG) in 27 of 29 neurones investigated. 4. DHPG-induced LTD was associated with an increase in both the paired-pulse facilitation ratio and the coefficient of variation of EPSCs. 5. Using dendritic recording, there was a decrease in EPSC success rate (number of trials that elicited a detectable response) but no change in potency (mean EPSC amplitude excluding failures) associated with DHPG-induced LTD. 6. In experiments using dissociated hippocampal cultures, application of DHPG elicited a persistent decrease in the frequency of tetrodotoxin-resistant miniature EPSCs but no change in the amplitude of such events. 7. DHPG-induced LTD was not blocked by intracellular application of the calcium chelator BAPTA. It was also unaffected when intracellular calcium stores were depleted by perfusion with thapsigargin. Furthermore, when synaptic transmission was blocked by perfusing with Ca2+-free medium, DHPG application reliably induced LTD. 8. These data suggest that DHPG-induced LTD is Ca2+ independent and is expressed presynaptically.

Synergistic outside-in regulation of platelet activation by GPIIb/IIIa ligand-induced conformation and oligomerization

Full platelet activation with serotonin secretion and thromboxane A(2) (TxA(2)) formation induced by a low dose of thrombin receptor agonist peptide (TRAP) or high dose ADP requires platelet aggregation. This requirement can be replaced by pretreatment of platelets with a combination of reagents including: GPIIb/IIIa inhibitors yielding ligand-induced binding sites (LIBS), either arginine-glycine-aspartate-serine (RGDS) peptide or Ro 43-5054, cytochalasin to disrupt actin filaments and crosslinking by a GPIIb/IIIa mAb (pl-62). Crosslinking is required since Fab fragments of pl-62 do not support activation. Engagement of the Fc receptor by the mAb Fc domain is not required for pl-62 augmentation, since it is not blocked by the anti-Fc receptor mAb, IV-3. Another GPIIb/IIIa inhibitor, Ro 44-9883, not yielding LIBS epitopes, serves as a negative control and shows a requirement for LIBS in addition to crosslinking. Focal adhesion kinase tyrosine phosphorylation induced by TRAP is blocked by these GPIIb/IIIa antagonists, but restored by pl-62 crosslinking independent of LIBS induction. Tyrosine phosphorylation of a peptide comigrating with p38 MAP kinase is also inhibited by these antagonists and restored by pl-62 crosslinking. However, p38 MAP kinase activation by low dose TRAP is not affected by these aggregation inhibitors. Tyrosine phosphorylation of a 34-kDa phosphoprotein in the absence of aggregation or TxA(2) formation was uniquely augmented by Ro 43-5054 but not Ro 44-9883 under the above activation conditions.

Functional properties of Drosophila inositol trisphosphate receptors

The functional properties of the only inositol trisphosphate (IP(3)) receptor subtype expressed in Drosophila were examined in permeabilized S2 cells. The IP(3) receptors of S2 cells bound (1,4,5)IP(3) with high affinity (K(d)=8.5+/-1.1 nM), mediated positively co-operative Ca(2+) release from a thapsigargin-sensitive Ca(2+) store (EC(50)=75+/-4 nM, Hill coefficient=2.1+/-0.2), and they were recognized by an antiserum to a peptide conserved in all IP(3) receptor subtypes in the same way as mammalian IP(3) receptors. As with mammalian IP(3) receptors, (2,4,5)IP(3) (EC(50)=2.3+/-0.3 microM) and (4,5)IP(2) (EC(50) approx. 10 microM) were approx. 20- and 100-fold less potent than (1,4,5)IP(3). Adenophostin A, which is typically approx. 10-fold more potent than IP(3) at mammalian IP(3) receptors, was 46-fold more potent than IP(3) in S2 cells (EC(50)=1.67+/-0.07 nM). Responses to submaximal concentrations of IP(3) were quantal and IP(3)-evoked Ca(2+) release was biphasically regulated by cytosolic Ca(2+). Using rapid superfusion to examine the kinetics of IP(3)-evoked Ca(2+) release from S2 cells, we established that IP(3) (10 microM) maximally activated Drosophila IP(3) receptors within 400 ms. The activity of the receptors then slowly decayed (t(1/2)=2.03+/-0.07 s) to a stable state which had 47+/-1% of the activity of the maximally active state. We conclude that the single subtype of IP(3) receptor expressed in Drosophila has similar functional properties to mammalian IP(3) receptors and that analyses of IP(3) receptor function in this genetically tractable organism are therefore likely to contribute to understanding the roles of mammalian IP(3) receptors.

A real-time approach to detect seal defects in food packages using ultrasonic imaging

The microbial integrity of many types of flexible food packages depends on a zero defect level in the fused seam seal. Human inspection for defects in these seals is marginal at best, and secondary incubation protocols are often used to spot packages with compromised integrity before releasing product for sale. A new type of inspection method has been developed and is being evaluated for robustness. The purpose of the study was to evaluate a new raster scanning geometry to simulate continuous motion, online ultrasonic inspection of the seal region in flexible food package seals. A principal engineering tradeoff of scanning inspection systems is between increased line speed that results from decreased spatial sampling (less acquired data to process) and decreased image quality. The previously developed pulse-echo Backscattered Amplitude Integral (BAI) mode imaging technique is used to form ultrasound images using the new scanning geometry. At an ultrasonic frequency of 22.9 MHz, 38- and 50-microm-diameter air-filled channel defects in all-plastic transparent trilaminate are evaluated. The contrast-to-noise ratio (CNR) of the processed BAI-mode image is used to quantify image quality as a function of spatial sampling. Results show seal defects (38- and 50-microm diameter) are still detectable for undersampled conditions, although image quality degrades as spatial sampling decreases. Further, it is concluded that the raster scanning geometry is feasible for online inspection.

Lotrafiban: an oral platelet glycoprotein IIb/IIIa blocker

Platelets play a major role in thrombus formation, as well as in the pathogenesis of atherothrombosis. Inhibition of platelet function is now emphasised more than ever for prevention and treatment of almost all vascular diseases, since thrombosis is established as the key pathogenic event causing acute ischaemic coronary and cerebrovascular syndromes. Although acetylsalicylic acid (aspirin) has been shown to reduce the incidence of myocardial infarction and stroke, its effect is weak and more effective antithrombotic agents are required to manage patients at high-risk for recurrent vascular events. Platelet glycoprotein IIb/IIIa receptor (GPIIb/IIIa) blockade represents a significant advance in interventional cardiology and treatment of acute ischaemic syndromes. The past several years have seen the introduction of many platelet GPIIb/IIIa blockers into the clinical arena targeting the unique platelet GPIIb/IIIa receptor for the adhesive proteins, fibrinogen and von Willebrand Factor. Platelet GPIIb/IIIa blockers administered intravenously have proven efficacious in mitigating arterial thrombosis in acute coronary syndromes (unstable angina and non-ST-elevation myocardial infarction) and percutaneous coronary interventions (PCI) such as balloon dilatation and stent implantation. Currently, orally-active platelet GPIIb/IIIa blockers are being developed to provide additional benefits for primary and secondary prevention of thrombosis as chronic treatment, especially in high-risk patients. Lotrafiban (SmithKline Beecham) is a member of the latest generation of orally-active platelet GPIIb/IIIa blockers undergoing Phase III clinical trials to test the relative effectiveness versus other oral platelet inhibitors for ischaemic conditions including unstable angina, restenosis after PCI and stroke. Lotrafiban is converted from an esterified prodrug by plasma and liver esterases to a peptidomimetic of the arginine-glycine-aspartic acid amino acid sequence. This sequence itself mimics the binding site of fibrinogen and von Willebrand Factor to the platelet GPIIb/IIIa receptor. Preliminary results of the clinical trial APLAUD (antiplatelet useful dose) show that lotrafiban is clinically safe and well-tolerated in patients with recent myocardial infarction, unstable angina, transient ischaemic attack (TIA), or stroke when added to aspirin therapy. With lotrafiban, a worldwide large-scale Phase III clinical trial BRAVO (blockage of the GPIIb/IIIa receptor to avoid vascular occlusion) is currently underway. In general, GPIIb/IIIa blockade seems clinically very promising. A number of unresolved issues, however, remain to be elucidated.

Myocardial expression of endothelin-1 in murine Trypanosoma cruzi infection

Chagas' disease, caused by Trypanosoma cruzi, is an important cause of myocarditis and chronic cardiomyopathy and is accompanied by microvascular spasm and myocardial ischemia. We reported previously that infection of cultured endothelial cells with T. cruzi increased the synthesis of biologically active endothlein-1 (ET-1). In the present study, we examined the role of ET-1 in the cardiovascular system of CD1 mice infected with the Brazil strain of T. cruzi and C57BL/6 mice infected with the Tulahuen strain during acute infection. In the myocardium of infected mice myonecrosis and multiple pseudocysts were observed. There was also an intense vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium. Immunohistochemistry studies employing anti-ET-1 antibody revealed increased expression of ET-1 that was most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for preproET-1, endothelin converting enzyme and ET-1 were observed in the same myocardial samples. Plasma ET-1 levels were significantly elevated in infected CD1 mice 10-15 days post infection. These observations suggest that increased levels of ET-1 are a consequence of the initial invasion of the cardiovascular system and provide a mechanism for infection-associated myocardial dysfunction.

Clinical utility of CKMB isoform determinations in patients who present to the emergency department with continuous or resolved chest pain

The object of this investigation was to demonstrate that the enhanced sensitivity of the diagnosis of acute myocardial infarction (AMI) using a more-inclusive criterion of CKMB Isoforms may detect earlier stages of AMI (designated Isoform Type 2) than the currently accepted marker for AMI by CKMB Isoform (designated Isoform Type 1) in a busy, urban Emergency Department (ED). Two features characterized the study of CKMB Isoforms in a prospective cohort of 223 ED patients: first, nontraumatic chest pain within 12 h before presentation, thought to be of ischemic etiology; and second, normal or nondiagnostic electrocardiogram (EKG). Patients were further divided into two groups characterized as either recent but resolved chest pain at ED visit, or ongoing or staccato chest pain. Sensitivity (S), specificity (SP), positive (PPV) and negative (NPV) predictive values, and 95% confidence intervals (CI) for AMI diagnosis were determined. Two criteria for AMI diagnosis by CKMB Isoforms were tested. The first and currently recommended criterion was identified as Isoform Type 1. An AMI diagnosis by Type 1 criterion requires both CKMB2> or =2.6 IU/L and CKMB2/CKMB1> or =1.7. The second criterion for AMI diagnosis was identified as Isoform Type 2, which is defined as either CKMB2> or =2.6 IU/L or CKMB2/CKMB1> or =1.7. Both Isoform types are predictive of AMI by the gold standard, and addition of EKG changes results in a small improvement. Type 1 demonstrates SP 0.94 (CI 0.90, 0.97) and NPV 0.90 (CI 0.86, 0.94), and Type 2 demonstrates S 0.90 (CI 0.80, 0.97) and NPV 0.97 (CI 0.93, 0.99) for AMI diagnosis. Type 2 criteria can confidently exclude the immediate risk of AMI in patients with resolved chest pain whereas in patients with continuous chest pain, Type 1 criteria may identify those at high risk for AMI.

The influence of an Urgent Care Center on the frequency of ED visits in an urban hospital setting

We examined the effect of a visit to an Urgent Care Center (UCC) on emergency department (ED) use by patients with nonemergent complaints. A study population of 1,629 patients with no previous visit to a UCC were identified and served as their own controls. The ED and clinic usage 6 months before and 6 months after a UCC visit were examined. After the UCC visit for adults there was a 48% reduction in ED visits (P = .0001) and 49% increase in clinic visits (P = .0001). After the UCC visit for children there was a 28% reduction in ED visits (P < .005) and 65% increase in clinic visits (P = .0001). Moreover the majority of clinic visits occurred within 90 days after the UCC visit. There was no substantial change in patterns of hospitalization 6 months after the UCC visit. We conclude that UCC usage decreases nonemergent ED use without adverse effects of increased patient hospitalization.

Ca2+-calmodulin inhibits Ca2+ release mediated by type-1, -2 and -3 inositol trisphosphate receptors

InsP(3) binding to type-1, but not type-3, InsP(3) receptors is inhibited by calmodulin in a Ca(2+)-independent fashion [Cardy and Taylor (1998) Biochem. J. 334, 447-455], and Ca(2+) mobilization by type-1 InsP(3) receptors of cerebellum is inhibited by calmodulin [Patel, Morris, Adkins, O'Beirne and Taylor (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 11627-11632]. Using cell types expressing predominantly type-1, -2 or -3 InsP(3) receptors, we show that InsP(3)-evoked Ca(2+) mobilization from each is similarly inhibited by calmodulin. In SH-SY5Y cells, which express largely type-1 receptors, calmodulin (IC(50) approximately 15 microM) inhibited InsP(3)-evoked Ca(2+) release only in the presence of Ca(2+). The inhibition was unaffected by calcineurin inhibitors. The effect of calmodulin did not result from enhanced metabolism of InsP(3) because calmodulin also decreased the sensitivity of the Ca(2+) stores to adenophostin A, a non-metabolizable InsP(3)-receptor agonist. Protein kinase A-catalysed phosphorylation of type-1 InsP(3) receptors was unaffected by Ca(2+)-calmodulin. Using a scintillation proximity assay to measure (125)I-calmodulin binding to glutathione S-transferase-fusion proteins, we identified two regions of the type-1 InsP(3) receptor (cyt1, residues -6 to 159; and cyt11, residues 1499-1649) that bound (125)I-calmodulin. The higher-affinity site (cyt11) was also photoaffinity labelled with N-hydroxysuccinimidyl-4-azidobenzoate (HSAB)-calmodulin. We speculate that Ca(2+)-independent binding of calmodulin to a site within the first 159 residues of the type-1 InsP(3) receptor inhibits InsP(3) binding and may thereby regulate the kinetics of Ca(2+) release. Ca(2+)-dependent inhibition of Ca(2+) release by calmodulin is mediated by a different site: it may reside on an accessory protein that associates with all three receptor subtypes, or Ca(2+)-calmodulin binding to a site lying between residues 1499 and 1649 of the type-1 receptor may inhibit Ca(2+) release from any tetrameric receptor that includes a type-1 subunit.

Parametric modeling in food package defect imaging

A novel approach in food package defect detection is proposed based on system identification theory, in which the channel defect detection problem can be regarded as the conventional system identification problem, i.e., estimation of the system impulse response based on the input-output sequence using parametric and nonparametric models. The well-known parametric model ARX has been investigated in this paper. The data are collected with a focused ultrasound transducer (17.3 MHz, 6.35-mm diameter, f/2, 173 microm -6 dB pulse-echo lateral beam width at the focus) scanned over a rectangular grid, keeping the packages in the focus. Performance is measured in terms of detection rate, image contrast, and contrast-to-noise ratio. The results using the ARX model are compared with previous image formation techniques and also compared with the non-parametric method, i.e., spectral analysis. The results show that the ARX model has the comparable detection rate as RFCS and higher detection rate than BAI and RFS (except 6-microm air-filled channel in plastic trilaminate film) for channel in plastic trilaminate film. The ARX model has achieved the moderate contrast enhancement and ranks second in contrast-to-noise ratio enhancement among the compared techniques. The ARX model has a low detection rate for channel defects in aluminum trilaminate film, which shows that its performance is material-dependent. Finally, the parametric method, ARX model demonstrates better performance than the non-parametric method, spectral analysis for food package defect detection.

High contrast ultrasound images of defects in food package seals

Previous work to detect defects in food packaging seals using pulse-echo ultrasound inspired the backscattered amplitude integral (BAI) imaging technique, which could reliably identify channels with diameters 38 microm or larger at a center frequency of 17.3 MHz (lambda=86 microm). The current study presents two new processing techniques that more reliably reveal smaller channels ( approximately 6 microm in diameter). The RF sampling technique (RFS) displays a single, time-gated, pressure value from the received (not envelope-detected) RF waveform at each transducer position. The RF correlation technique (RFC) calculates the correlation coefficients of the RF signals with a reference signal that does not pass through a channel. The correlation coefficient can be calculated for the entire RF signal (RFCE) or over a short segment of the RF signal (RFCS). The performance of these imaging methods for detecting channel defects is investigated for plastic and aluminum foil trilaminate films with 6, 10, 15, 38, and 50 microm channels filled with water or air. Data are collected with a focused ultrasound transducer (17.3 MHz, 6.35 mm in diameter, f/2, 173 microm -6 dB pulse-echo lateral beamwidth at the focus) scanned over a rectangular grid, keeping the package in the focus. Performance is measured using detection rates, image contrast, and contrast-to-noise ratio (CNR). Both RFS and RFCS have improved detection rates relative to BAI for channels 15 microm or smaller. The RFCS technique is the most effective at smoothing the background, leading to the greatest CNR improvements.

Hyalodendrosides A and B, antifungal triterpenoid glycosides from a lignicolous hyphomycete, Hyalodendron species

Two antifungal triterpenoid glycosides, hyalodendrosides A and B (1 and 2), were isolated from a solid matrix fermentation of a lignicolous hyphomycete, Hyalodendron sp. Their structures were determined based upon extensive examination of spectral parameters, particularly NMR and MS data. Both compounds have beta-linked glucose moieties. Compounds 1 and 2 show weak to moderate antifungal activity against some clinically relevant fungi.

Type 3 inositol trisphosphate receptors in RINm5F cells are biphasically regulated by cytosolic Ca2+ and mediate quantal Ca2+ mobilization

There are three subtypes of mammalian Ins(1,4,5)P(3) (InsP(3)) receptor, each of which forms an intracellular Ca(2+) channel. Biphasic regulation of InsP(3) receptors by cytosolic Ca(2+) is well documented in cells expressing predominantly type 1 or type 2 InsP(3) receptors and might contribute to the regenerative recruitment of Ca(2+) release events and to limiting their duration in intact cells. The properties of type 3 receptors are less clear. Bilayer recording from InsP(3) receptors of RIN-5F cells, cells in which the InsP(3) receptors are likely to be largely type 3, recently suggested that the receptors are not inhibited by Ca(2+) [Hagar, Burgstahler, Nathanson and Ehrlich (1998) Nature (London) 296, 81-84]. By using antipeptide antisera that either selectively recognized each InsP(3) receptor subtype or interacted equally well with all subtypes, together with membranes from Spodoptera frugiperda (Sf9) cells expressing only single receptor subtypes to calibrate the immunoblotting, we quantified the relative levels of expression of type 1 (17%) and type 3 (77%) InsP(3) receptors in RINm5F cells. In unidirectional (45)Ca(2+) efflux experiments from permeabilized RINm5F cells, submaximal concentrations of InsP(3) released only a fraction of the InsP(3)-sensitive Ca(2+) stores, indicating that responses to InsP(3) are quantal. Increasing the cytosolic free [Ca(2+)] ([Ca(2+)](i)) from approx. 4 to 186 nM increased the sensitivity of the Ca(2+) stores to InsP(3): the EC(50) decreased from 281+/-15 to 82+/-2 nM. Further increases in [Ca(2+)](i) massively decreased the sensitivity of the stores to InsP(3), by almost 10-fold when [Ca(2+)](i) was 2.4 microM, and by more than 3000-fold when it was 100 microM. The inhibition caused by 100 microM Ca(2+) was fully reversed within 60 s of the restoration of [Ca(2+)](i) to 186 nM. The effect of submaximal InsP(3) concentrations on Ca(2+) mobilization from permeabilized RINm5F cells is therefore biphasically regulated by cytosolic Ca(2+). We conclude that type 3 InsP(3) receptors of RINm5F cells mediate quantal Ca(2+) release and they are biphasically regulated by cytosolic Ca(2+), either because a single type 1 subunit within the tetrameric receptor confers the Ca(2+) inhibition or because the type 3 subtype is itself directly inhibited by Ca(2+).

Scaling ADLs within the MDS

BACKGROUND

Dependency in activities of daily living (ADLs) is a reality within nursing homes, and we describe ADL measurement strategies based on items in the Minimum Data Set (MDS) and the creation and distributional properties of three ADL self-performance scales and their relationship to other measures.

METHODS

Information drawn from four data sets for a multistep analysis was guided by four study objectives: (1) to identify the subcomponents of ADLs that are present in the MDS battery; (2) to demonstrate how these items could be aggregated within hierarchical and additive ADL summary scales; (3) to describe the baseline and longitudinal distributional properties of these scales in a large, seven-state MDS database; and (4) to evaluate how these scales relate to two external criteria.

RESULTS

Prevalence and factor structure findings for seven MDS ADL self-performance variables suggest that these items can be placed into early, middle, and late loss ADL components. Two types of summary ADL self-performance measures were created: additive and hierarchical. Distributional properties of these scales are described, as is their relationship to two external ADL criteria that have been reported in prior studies: first as an independent variable predicting staff time involved in resident care; second as a dependent variable in a study of the efficacy of two programs to improve resident functioning.

CONCLUSIONS

The new ADL summary scales, based on readily available MDS data, should prove useful to clinicians, program auditors, and researchers who use the MDS functional self-performance items to determine a resident's ADL status.

Developmental sensitivity of the piglet brain to docosahexanoic acid

Human formula-fed infants have a lower concentration of docosahexanoic acid (DHA) in cerebral cortex compared with breast-fed infants. It is uncertain whether this biochemical deficit is reversible in later infancy. We used a piglet model to determine whether a critical window exists for the deposition of DHA in cerebral cortex during early postnatal development. Milk formula supplemented with DHA was fed to piglets for one of two 14-day periods commencing at either 2 or 16 d of life (early or late supplementation). Comparison of cortical DHA levels in response to supplemented formula was made with age-matched piglets receiving a control formula devoid of DHA. The level of DHA incorporated into whole brain during supplemented formula-feeding seemed to be less with increasing postnatal age. However, when cerebral cortex was examined, dietary DHA was efficiently incorporated during both early and late supplementation periods. Thus, analysis of whole brain was misleading, emphasizing the need to consider the effect of myelination when interpreting developmental changes in brain fatty acids. We conclude that the piglet cerebral cortex is responsive to dietary DHA during the postnatal phase of the brain growth spurt. The lower cortical DHA levels of human formula-fed infants may, therefore, be reversible in later infancy. Plasma phospholipid DHA levels were approximately doubled and liver phospholipid DHA levels increased 50% relative to starting values during control formula-feeding. This suggests a higher rate of DHA synthesis in the piglet in comparison with the human infant, which may be an important limitation of the piglet model.

The putative mechanistic basis for the modulatory role of endothelin-1 in the altered vascular tone induced by Trypanosoma cruzi

Chagas' disease, caused by Trypanosoma cruzi, is an important cause of heart disease in Latin America. T. cruzi-induced microvascular compromise, in turn, is thought to play a major role in chagasic heart disease. Previous in vitro studies have implicated endothelin-1 (ET-1) as a potentially important vasomodulator present in increased levels in the supernatant of T. cruzi infected cultured human umbilical vein endothelial cells (HUVEC). Thus, the goal of the present investigation was to further evaluate the potentially important contribution of ET-1 to T. cruzi-induced alterations in vascular tone in vitro. Bioassay studies once again documented that exposure of isolated rat aortic rings to infected HUVEC supernatants elicited contractile responses whose steady-state magnitude was significantly greater than contractile responses elicited by exposure of aortic rings to uninfected HUVEC supernatants. Furthermore, the increased aortic contractility was significantly attenuated by the presence of the ET(A) subtype selective antagonists BMS-182,874 or BQ-123. Additionally, incubation of HUVEC with either verapamil or phosphoramidon prior to infection was also associated with reduced aortic contractility, upon exposure to the supernatant. Phosphoramidon, but not verapamil, produced a significant decrease in the measured ET-1 levels in the HUVEC supernatant. Consistent with the bioassay results, preincubation of Fura-2-loaded cultured rat aortic vascular smooth muscle cells with verapamil resulted in a near complete ablation of ET-1-induced transmembrane Ca2+ flux. Taken together, these data are consistent with the hypothesis that ET-1-induced vasoconstriction may play an important modulatory role in the vascular compromise characteristic of T. cruzi infection.

Interactions between inositol trisphosphate receptors and fluorescent Ca2+ indicators

Fura-2 and BAPTA were previously shown to be competitive antagonists of inositol trisphosphate (InsP3) receptors, but for practical reasons the analyses were performed at pH 8.3. We recently developed a scintillation proximity assay (SPA) for pure cerebellar InsP3 receptors which allows low affinity interactions to be characterized and is readily applicable to scarce or expensive ligands. In the present study, we use SPA to demonstrate that at pH 7.2, many of the commonly used fluorescent Ca2+ indicators reversibly displace 3H-InsP3 from its receptor and that they differ substantially in their affinities for the InsP3 receptor (IC50 = 6.5-137 microM). Recombinant type 1 InsP3 receptors expressed in Sf9 cells were used to examine 3H-InsP3 binding in cytosol-like medium: both fura-2 (IC50 = 796 +/- 86 microM) and Ca Green-5N (IC50 = 62 +/- 7 microM) completely inhibited the binding, but only in their Ca(2+)-free forms. Similar results were obtained with type 3 InsP3 receptors. We conclude that many Ca2+ indicators in their Ca(2+)-free forms compete with InsP3 for binding to its receptor, and that for Ca Green-5N the interaction occurs with sufficient affinity to significantly perturb physiological responses.

Influence of antiresorptive agent OST-766 on signal transduction pathways involved in parathyroid hormone action

The effects of OST-766, an inhibitor of vacuolar H+-ATPase activity, on adenylyl cyclase and phospholipase C activity were explored in the osteoblast cell line ROS 17/2.8. In fresh homogenates of ROS 17/2.8 cells, OST-766 inhibited adenylyl cyclase activity (ACA) in response to guanine nucleotide and forskolin but had no effect on basal ACA. OST-766 enhanced the basal generation of IP2, but not that formed in response to Ca2+ or guanine nucleotides. In marked contrast, incubation of intact ROS 17/2.8 cells with OST-766 for at least 48 hours resulted in an increase in basal ACA as well as in response to PTH, guanine nucleotides and forskolin. Under similar conditions, the compound also increased IP1, IP2 and IP3 generation in response to guanine nucleotides and Ca2+. Levels of the guanine nucleotide binding proteins Gs and Gi were also increased in OST-766-treated cells. The results suggest that the actions of this H+-ATPase inhibitor include effects on osteoblasts through PTH-sensitive signal transduction pathways.

Expression of cardiac cytokines and inducible form of nitric oxide synthase (NOS2) in Trypanosoma cruzi-infected mice

Expression of Cardiac Cytokines and Inducible Form of Nitric Oxide Synthase (NOS2) in Trypanosoma cruzi-infected Mice. Journal of Molecular and Cellular Cardiology (1999) 31, 75-88. Both cardiac cytokine and inducible nitric oxide synthase (NOS2) expression have been implicated in the cardiac dysfunction associated with myocarditis and cardiomyopathy. Chagas' disease, caused by Trypanosoma cruzi, is an important cause of cardiomyopathy. We examined the effect of T. cruzi (Brazil strain) infection with or without verapamil treatment on the expression of cytokines and NOS2 in the heart. Messenger RNA for NOS2, IL-1beta, and TNF-alpha was induced in the myocardium of infected mice, and Western blot analysis as well as immunohistochemistry demonstrated a significant increase in NOS2 protein. Verapamil treatment reduced the expression of cardiac NOS2 protein and the mRNAs for NOS2, TNF-alpha, and IL-1beta. Infection-associated increases in cardiac L-citrulline were also reduced by verapamil treatment. Verapamil-treated infected mice that survived for 80 days exhibited less inflammation and fibrosis compared to untreated mice. Gated MRI and echocardiography revealed an increased right ventricular inner diameter (RVID) in untreated but not in verapamil-treated infected CD1 mice. This suggests that the infection-associated expression of cytokines and NOS2 in the heart correlate with the severity of myocarditis and the effect of verapamil. The RVID was significantly increased in infected wild-type (WT) compared to infected syngeneic NOS2 knockout (NOS2-/-) mice. Fractional shortening was decreased and myocardial L-citrulline was increased in infected WT mice. These data suggest that NO generated from cardiac NOS2 may participate in the pathogenesis of murine chagasic heart disease.

A novel AP180-related protein in vesicles that concentrate at acetylcholine receptor clusters

Monoclonal antibodies were generated to vesicular membranes of clathrin coated vesicles enriched for acetylcholinesterase (AChE). One of these, C172, recognizes vesicles which accumulate in muscle cells around nuclei associated with acetylcholine receptor AChR clusters. Immunoblots of muscle extracts and brain purified clathrin coated vesicles show that C172 recognizes a 100 kd band in muscle, but a 180 kd band in brain. Western blots of purified AP180 protein stained with the two antibodies AP180.1 and C172 displayed the same staining pattern. Tryptic digests probed with peptide antibodies (PS26 and PS27) generated to known sequences of AP180 were used to map the epitope for C172 within the brain AP180 sequence. On immunoblots of digested AP180, all AP180 antibodies and C172 recognized a 100 kd tryptic fragment, however only C172 recognized a smaller 60 kd. Our results suggest that the C172 epitope is located within amino acids 305-598 of the AP180 sequence. Confocal fluorescence microscopy of myoblasts and myotubes stained with the C172 antibody gives a punctate immunofluorescence pattern. Myoblasts stained with C172 revealed a polarized distribution of vesicles distinct from that observed when cells are stained with gamma adaptin antibody which is known to localize to trans Golgi network. Myotubes stained with C172 antibody reveal a linear array of vesicular staining. Quantitative analysis of C172 reactive vesicles revealed a significant increase in number of vesicles present around the nuclei associated with the acetylcholine receptor clusters. These vesicles did not colocalize with the Golgi cisternae. These results indicate that a protein with homology to the neuron-specific coated vesicle protein AP180, is present in muscle cells associated with vesicles showing significant concentration around postsynaptic nuclei present in close proximity to AChR clusters.

Intracellular Ca2+ homeostasis in trypomastigotes of Trypanosoma cruzi

Trypomastigotes of Trypanosoma cruzi maintain an intracellular Ca2+ concentration ([Ca2+]i) of 64 +/- 30 nM. Equilibration of trypomastigotes in an extracellular buffer containing 0.5 mM [Ca2+]o (preloaded cells) increased [Ca2+]i < 20 nM whereas total cell Ca2+ increased by 1.5 to 2.0 pmole/cell. This amount of Ca2+ would be expected to increase [Ca2+]i to > 10 microM suggesting active sequestration of Ca2+. We tested the hypothesis that maintenance of [Ca2+]i involved both the sequestration into intracellular storage sites and extrusion into the extracellular space. Pharmacological probes known to influence [Ca2+]i through well characterized pathways in higher eukaryotic cells were employed. [Ca2+]i responses in the presence or absence of [Ca2+]o were measured to asses the relative contribution of sequestration or extrusion processes in [Ca2+]i homeostasis. In the presence of 0.5 mM [Ca2+]o, the ability of several agents to increase [Ca2+]i was magnified in the order ionomycin >>> nigericin > thapsigargin > monensin > valinomycin. In contrast, preloading markedly enhanced the increase in [Ca2+]i observed only in response to monensin. Manoalide, an inhibitor of phospholipase A2, enhanced the accumulation of [Ca2+]i due to all agents tested, particularly ionomycin and thapsigargin. Our results suggest that sequestration of [Ca2+]i involved storage sites sensitive to monensin and ionomycin whereas extrusion of Ca2+ may involve phospholipase A2 activity. A Na+/Ca2+ exchange mechanism did not appear to contribute to Ca2+ homeostasis.

Channel defect detection in food packages using integrated backscatter ultrasound imaging

Hermetically-sealed flexible food packages require very effective seal integrity testing to extend the shelf stability of thermally processed food. The initial goal of this study was to estimate the detection limits of laboratory-generated channels which simulate defects in food packages using pulse-echo ultrasonic imaging techniques. Packages with well characterized (via transmission optical microscopy) laboratory-generated channels that simulate defects with diameters between 9 and 325 microm in the seal plane traversing the major axis of the heat seal were generated in heat-sealed microwavable retort-pouch plastic film (trilaminate). Pulse-echo techniques in the 13-17 MHz center frequency range were investigated. The samples were examined with a conventional B-mode imaging technique, which was found to be inadequate for subwavelength imaging of the types of typical channel defects found in shelf-stable food packages. Based on conventional B-mode image features, a new goal of this study was established to develop and evaluate an imaging technique which would exhibit subwavelength imaging capabilities. The new imaging technique called backscattered amplitude integral (BAI) is introduced here. It was observed that BAI-mode imaging has the ability for subwavelength detection of channel defects, e.g., detection of a 10-microm diameter channel defect at a center frequency of 13.1 MHz (lambda=182 microm).

The effect of specific medical conditions on functional decline

OBJECTIVES

To examine how functional status among older community-dwelling residents differs over time between those with and those without specific medical conditions.

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 1060 community-dwelling Massachusetts residents aged 65 or older who were not totally functionally dependent at baseline assessment.

MEASUREMENTS

Functional status, five medical conditions (heart problem, arthritis, diabetes, cancer, and stroke), and the total number of these five medical conditions. Assessments were done at baseline and at two annual follow-ups.

RESULTS

Adjusted repeated measures analysis of covariance revealed a time difference (P < .001) for all five medical conditions and group differences for diabetes (P = .006) and stroke (P < .001). Functional abilities declined over time and those with specific medical conditions were more impaired initially, but the rate of decline did not significantly differ from those free of the condition. The presence of each additional medical condition resulted in additional impairment (P < .001), but the rate of decline over time did not differ by number of medical conditions.

CONCLUSIONS

Efforts to reduce or prevent the development of specific medical conditions are essential to maintaining functional independence of older people as well as to reducing use of supportive services and admission rates to nursing homes. Particular attention should be directed toward preventing stroke since its consequences are the most functionally disabling.

Ca2+-independent inhibition of inositol trisphosphate receptors by calmodulin: redistribution of calmodulin as a possible means of regulating Ca2+ mobilization

The interactions between calmodulin, inositol 1,4,5-trisphosphate (InsP3), and pure cerebellar InsP3 receptors were characterized by using a scintillation proximity assay. In the absence of Ca2+, 125I-labeled calmodulin reversibly bound to multiple sites on InsP3 receptors and Ca2+ increased the binding by 190% +/- 10%; the half-maximal effect occurred when the Ca2+ concentration was 184 +/- 14 nM. In the absence of Ca2+, calmodulin caused a reversible, concentration-dependent (IC50 = 3.1 +/- 0.2 microM) inhibition of [3H]InsP3 binding by decreasing the affinity of the receptor for InsP3. This effect was similar at all Ca2+ concentrations, indicating that the site through which calmodulin inhibits InsP3 binding has similar affinities for calmodulin and Ca2+-calmodulin. Calmodulin (10 microM) inhibited the Ca2+ release from cerebellar microsomes evoked by submaximal, but not by maximal, concentrations of InsP3. Tonic inhibition of InsP3 receptors by the high concentrations of calmodulin within cerebellar Purkinje cells may account for their relative insensitivity to InsP3 and limit spontaneous activation of InsP3 receptors in the dendritic spines. Inhibition of InsP3 receptors by calmodulin at all cytosolic Ca2+ concentrations, together with the known redistribution of neuronal calmodulin evoked by protein kinases and Ca2+, suggests that calmodulin may also allow both feedback control of InsP3 receptors and integration of inputs from other signaling pathways.

Anesthetic management of patients receiving calculus therapy with a third-generation extracorporeal lithotripsy machine

We reviewed the anesthetic requirements for satisfactory use of a third-generation electromagnetic-source design for extracorporeal shockwave lithotripsy (SWL). Medical records were reviewed for a period of 9 months on all patients receiving anesthesia care for SWL with and without other urologic procedures. The Modulith SL20 was used on 56 ASA Class I-III patients having 87 SWL treatments. Demographic and anesthetic variables were recorded. Complications documented included dysrhythmias, nausea necessitating treatment, and conversion from sedation to regional or general anesthesia. The majority of procedures (83%) were performed on an outpatient basis. Patients were classified as ASA physical status I (27%), II (63%), or III (10%). Monitored anesthesia care with intravenous sedation was utilized in 93% of cases. Of these cases, 78 involved a combination of intravenous propofol, fentanyl, and midazolam; the remaining 3 involved propofol, alfentanil, and/or midazolam. The mean treatment duration was 36 minutes. Patients were discharged within 1 hour after procedure completion in 77 cases (89%). Nausea necessitating treatment was rare (3%). The mean dose of propofol administered with SWL as the only procedure was 272 +/- 112 mg. When SWL was combined with other urologic procedures, the mean dose of propofol was 334 +/- 121 mg. Continuous intravenous propofol infusion provides excellent procedural conditions for SWL on the Modulith SL120, a third-generation lithotripter.

Myocardial G proteins in murine Chagas' disease

G protein alpha subunits and their corresponding mRNA levels were determined in hearts obtained from mice infected with Trypanosoma cruzi, the etiologic agent of Chagas' disease. Protein and mRNA levels of the inhibitory G proteins G alpha i2 and G alpha i3 were increased at 21 and 30 days postinfection (PI). After 60 days, the abundance of protein and corresponding mRNA for G alpha i2 and G alpha i3 were no longer significantly different from uninfected mice. Twenty-one days after infection, G alpha s protein levels decreased markedly, but mRNA for the stimulatory protein did not change. Similar to the Gi proteins, by 60 days differences in G alpha s protein between infected and uninfected mice were no longer evident. There was an increase in the magnitude of G beta subunit protein 21 and 30 days PI as compared with uninfected mice. However, 60 days PI the G beta subunit protein decreased to control levels. The close relationship between the infection-associated increase in G alpha i protein and mRNA suggests that control of protein expression is likely to be exerted at the transcription level. In contrast, control of infection-associated decrease in Gs appears to be at the translational level.

The effect of LPS on cytokine synthesis and lung neutrophil influx after hepatic ischemia/reperfusion injury in the rat

OBJECTIVE

To determine if cytokine responses and lung injury induced by intravenous (i.v.) lipopolysaccharide (LPS) at 4 hr were enhanced in rats that had been previously subjected to 30 min of total liver ischemia (Pringle's maneuver) followed by 24 hr or 3 days of reperfusion.

BACKGROUND

Many patients with liver trauma require occlusion of hepatic blood flow to control hemorrhage and facilitate repair. A significant number of these patients subsequently develop the systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction (MOD) characterized by the release of cytokines and tissue neutrophil influx. Macrophages, including Kupffer cells, may be activated by ischemic injury and dysregulation of their response to LPS may contribute to the development of SIRS and acute respiratory distress syndrome.

METHODS

Adult male Sprague-Dawley rats were randomly divided into six groups: three groups received total hepatic ischemia for 30 min and three groups had a sham procedure. Twenty-four hours or 3 days after hepatic ischemia/reperfusion injury, rats were treated with LPS (5 mg/kg) or saline and monitored for 4 hr. We collected serum, bronchoalveolar lavage (BAL) fluid, and lung tissue.

RESULTS

Serum and BAL cytokine concentrations were significantly increased by i.v. LPS; however, hepatic ischemia/reperfusion injury 24 hr or 3 days before iv LPS ameliorated this cytokine response. The LPS-induced pulmonary neutrophil influx and histopathological changes were similar in sham and hepatic ischemia/reperfusion-injured groups.

CONCLUSIONS

Hepatic ischemia/reperfusion injury significantly attenuated the serum and BAL cytokine concentrations, but did not change pulmonary neutrophil influx or histopathological alterations in response to i.v. LPS.

Development, testing, and validation of two scales measuring nursing home management of subjects with mental disorder

This paper describes the development, testing, and validation of summary scales measuring nursing processes commonly used in caring for elderly nursing home residents with cognitive, mood, and behavior problems, or other markers of mental disorder. Data were obtained from a cross-sectional study of 1017 residents from a proportionate random sample in Delaware nursing facilities, to determine the prevalence of mental disorders and to describe distinguishing characteristics and treatments. An exploratory factor analysis was performed on 11 frequently encountered nursing management strategies as applied to 808 subjects with some indicator of mental disorder. Two factors emerged, which were subsequently conceptualized as separate scales (composed of six and five elements, respectively) that measure the basic approaches termed Encouragement and Control. Alpha reliability levels determined internal consistency for each scale. Cognitive, behavioral, and mood correlates were identified for each scale using multiple regression. Replication and validation were achieved when similar findings were obtained using a random sample of 290 residents at Hebrew Rehabilitation Center for Aged, a 725-bed long-term care facility in Boston. LISREL analyses confirmed the presence of at least two dimensions in behavior management strategies. The identification of these approaches is significant in providing non-pharmacologic and non-restraint alternatives to managing elderly residents with symptom distress.

Substituted glycals as probes of glycosidase mechanisms

D-Glucal and a series of substituted derivatives have been tested as substrates, inhibitors and inactivators of the Agrobacterium faecalis beta-glucosidase in order to probe structure/function relationships in this enzyme. D-Glucal is shown to be a substrate (kcat = 2.3 min-1, Km = 0.85 mM) undergoing hydration with stereospecific protonation from the alpha-face to yield 2-deoxy-beta-D-glucose. 1-Methyl-D-glucal surprisingly serves as only a poor substrate (kcat = 0.056 min-1, Km = 57 mM), also undergoing protonation from the alpha-face. 2-Fluoro-D-glucal, however is completely inert, as a result of inductive destabilisation of the oxocarbenium ion-like transition state for protonation, and functions only as a relatively weak (Ki = 24 mM) inhibitor. Similar behaviour was seen with almond beta-glucosidase and yeast alpha-glucosidase and for the interaction of 2-fluoro-D-galactal with Escherichia coli beta-galactosidase. A series of of alpha, beta-unsaturated glucal derivatives was also synthesised and tested as potential substrates, inhibitors or inactivators of A. faecalis beta-glucosidase. Of these only 1-nitro-D-glucal functioned as a time dependent, irreversible inactivator (ki = 0.011 min-1, Ki = 5.5 mM), presumably acting as a Michael acceptor. Electrospray mass spectrometric analysis revealed multiple labeling of the enzyme by this inactivator, lessening its usefulness as an affinity label. Less reactive Michael acceptor glycals which might have been more specific (1-cyano-, 2-cyano-, 1-carboxylic acid, 1-carboxylic acid methyl ester) unfortunately did not function as inactivators or substrates, only as relatively weak reversible inhibitors (Ki = 3-96 mM).

Effects of verapamil on acute murine Chagas' disease

Continuous administration of verapamil significantly reduced the mortality rate of acute murine Trypanosoma cruzi infection (P < 0.05). The mechanistic basis for these observations was investigated. Verapamil and other calcium-channel blockers did not inhibit the growth of epimastigotes in culture. Furthermore, verapamil did not inhibit the intracellular growth of amastigotes in endothelial cells as determined by the uptake of 3H-uracil. There were no significant differences in parasitemia between infected mice that were untreated and those treated with verapamil. Twenty days postinfection infected, untreated mice had a parasitemia of 5.8 x 10(6) trypomastigotes/ml (SD +/- 2 x 10(6)), whereas infected, verapamil-treated mice had a parasitemia of 2.2 x 10(6) trypomastigotes/ml (SD +/- 0.5 x 10(6)). There was no significant difference in mortality between mice administered verapamil only for the initial 10 days of murine infection compared to those treated continuously. A 3-day delay in the initiation of verapamil administration reduced the mortality rate, but a 10-day delay did not. Propranolol (beta-adrenergic blocker), prazosin (alpha 1-adrenergic blocker), and diltiazem (another calcium-channel blocker) reduced the mortality but not significantly (P = 0.07). In biochemical studies of the beta- adrenergic signal transduction complex, we determined that verapamil and propranolol reversed the infection-associated decrease in myocardial beta- adrenergic adenylyl cyclase activity. In contrast, complementary western blot analysis revealed no significant changes in the G-proteins of the beta- adrenergic receptor complex 45 days postinfection. Therefore, these results suggest that the basis of verapamil's influence on the early critical period of infection is multifactorial and independent of a direct trypanocidal effect.