Cellular immune responses against hepatitis C virus: the evidence base 2002

Hepatitis C virus (HCV) is an RNA virus which is estimated to persistently infect about 170 million people worldwide. After acute infection, there is an initial period during which long-term outcome is decided. There is strong evidence that the cellular immune responses, involving both CD4+ and CD8+ T lymphocytes, are involved at this stage and it is their effectiveness which determines outcome. What is not understood is what determines their effectiveness. The most important component of this is likely to be some aspect of epitope selection, itself dictated by host MHC. Thus, to understand host immunity to HCV, we need to have a detailed understanding of the peptides involved in T lymphocyte responses. In this review, we discuss the peptide epitopes that have been identified so far, and their potential significance. We relate this to a scheme of host defence which may be useful for understanding natural and vaccine-induced immunity.

Non-invasive method of evaluation of trophoblast invasion of spiral arteries in monochorionic twins with discordant birthweight

To test the hypothesis that variation in birthweight between twin pairs is due to discordant placental development, we determined spiral arterial blood flow by colour pulsed Doppler ultrasound scan. We prospectively studied 24 twin pregnancies in the late second trimester with (n=12) and without (n=12) inter-pair difference in estimated birthweight of > or = 20 per cent. In the discordant growth group, there were seven cases with chronic twin-twin transfusion syndrome (TTTS) and five without. The blood flow in spiral artery of each twin's portion of the placenta was assessed by resistance index (RI) by colour flow pulsed Doppler within a 5 cm radius of cord insertion. In twins with discordant weight, RI was increased in the growth restricted (FGR) twin than the appropriate for gestational age (AGA) co-twin (0.46 +/- 0.02 vs 0.3 +/- 0.01; P< 0.001) and the control group (P< 0.001). However, delta RI was comparable between twins with and without TTTS (0.13 +/- 0.01 vs 0.19 +/- 0.02; P=NS). No such differences were found between concordant twin pairs (0.28 +/- 0.01 vs 0.29 +/- 0.1; P=NS) and AGA twins of the discordant growth group. This study indicates that growth restricted twins have increased resistance to blood flow in the spiral arteries than the AGA co-twins. This observation, therefore, suggests non-physiological remodelling of the maternal spiral arteries in response to migrating trophoblast in placental bed of FGR MC twins.

Stereotactic core biopsy of breast microcalcifications: comparison of film versus digital mammography, both using an add-on unit

OBJECTIVE

The goal of this study was to assess the accuracy of an add-on stereotactic unit for core biopsy of indeterminate breast microcalcifications and to compare digital with conventional stereotactic guidance.

MATERIALS AND METHODS

We conducted a retrospective review of 232 lesions with indeterminate microcalcifications in 218 women who underwent stereotactically guided breast biopsies. All biopsies were performed using a standard mammography machine with an add-on unit, 121 with conventional and 111 with digital stereotactic guidance. Successful sampling of the lesion was determined by the detection of microcalcifications on specimen radiography or at pathology.

RESULTS

Using the add-on unit, 219 (94.4%) of the 232 targeted lesions were successfully sampled. The size, location, number of cores per lesion, and histology of the lesions were not different between the conventional and digital stereotactic biopsy groups (p > 0.1). Indeterminate microcalcifications were missed on biopsy in nine (7.4%) of 121 cases using conventional radiography and in only four (3.6%) of 111 cases using digital imaging. Digital stereotactic guidance allowed sampling of lesions with fewer calcifications per square centimeter (p < 0.001).

CONCLUSION

Sampling of indeterminate microcalcifications using a standard mammography machine and an add-on unit has a high accuracy, similar to rates reported for dedicated prone biopsy tables. An add-on unit offers the advantage of considerable cost and space savings. Relative to conventional radiography, digital stereotactic guidance allows lesions with fewer calcifications to be sampled and achieves a greater biopsy success rate. Immediate digital images in the biopsy room also permit rapid adjustment of alignment and minimize patient movement.

Placental transport rather than maternal concentration of amino acids regulates fetal growth in monochorionic twins: implications for fetal origin hypothesis

OBJECTIVE

The cause of discordant growth in monochorionic twins is not clear. We hypothesize that growth restriction of 1 monochorionic twin is due to fetal under-nutrition.

STUDY DESIGN

We measured plasma amino acid concentrations by high performance liquid chromatography in maternal venous and fetal umbilical cord venous blood samples that were collected at birth from gestational age-matched monochorionic twins (n = 14) with a birth weight discordance of > or =20%. The concordant monochorionic twins with birth weight differences of < or =10% constitute a control group.

RESULTS

In the intrauterine growth-restricted twins, fetal concentrations of essential amino acids valine (P <.01), leucine (P <.01), isoleucine (P <.01), phenylalanine (P <.01), and L-arginine (P <.05) were lower than the co-twins and concordant monochorionic twin pairs. Fetal concentrations of the nonessential amino acids taurine (P <.001), serine (P <.01), glycine (P <.01), tyrosine (P <.01), and aspartic acid (P <.01) were lower in the intrauterine growth-restricted twin than the co-twin or concordant monochorionic twins. No such differences were found between concordant monochorionic twin pairs. Maternal amino acid concentrations were similar between discordant and concordant groups.

CONCLUSION

Concentrations of certain essential and nonessential amino acids in the intrauterine growth-restricted twins were lower than the co-twins. These differences support the hypothesis that intrauterine growth-restriction that affects 1 of the monochorionic twins is due to the impaired placental transport of amino acids rather than intertwin transfusion of blood.

A representational approach to patient education

PURPOSE

To describe the theoretical basis for a representational approach to patient education and the application of this approach to the development, implementation, and preliminary evaluation of a representational intervention for pain management.

ORGANIZING CONSTRUCT

Leventhal's common sense model (CSM) was a guide for this approach to patient education. The CSM is based on the idea that people have common sense beliefs, or representations, that guide how they cope with health problems. Theoretically based interventions derived from the CSM have not been reported.

METHODS

Steps included: (a) designing a general approach to educational interventions, centered on illness representations; (b) specifying an intervention (RIDPAIN) to facilitate coping with cancer pain; (c) pilot-testing and revising the intervention; and (d) testing feasibility and acceptability of the intervention with 61 patients in a Midwestern American city.

FINDINGS

The RIDPAIN intervention was useful in eliciting misconceptions of pain and pain management from patients experiencing cancer pain. Many patients found RIDPAIN to be meaningful and useful, and they perceived it to have an effect on pain-related beliefs and behaviors.

CONCLUSIONS

This theory-driven approach should be effective and widely applicable because it includes patients as active participants in all phases of the learning continuum, from information acquisition to behavior change.

Metabolic power, mechanical power and efficiency during wind tunnel flight by the European starlingSturnus vulgaris

We trained two starlings (Sturnus vulgaris) to fly in a wind tunnel whilst wearing respirometry masks. We measured the metabolic power (Pmet) from the rates of oxygen consumption and carbon dioxide production and calculated the mechanical power (Pmech) from two aerodynamic models using wingbeat kinematics measured by high-speed cinematography. Pmet increased from 10.4 to 14.9 W as flight speed was increased from 6.3 to 14.4 m s–1 and was compatible with the U-shaped power/speed curve predicted by the aerodynamic models. Flight muscle efficiency varied between 0.13 and 0.23 depending upon the bird, the flight speed and the aerodynamic model used to calculate Pmech. Pmet during flight is often estimated by extrapolation from the mechanical power predicted by aerodynamic models by dividing Pmech by a flight muscle efficiency of 0.23 and adding the costs of basal metabolism, circulation and respiration. This method would underestimate measured Pmet by 15–25 % in our birds. The mean discrepancy between measured and predicted Pmet could be reduced to 0.1±1.5 % if flight muscle efficiency was altered to a value of 0.18. A flight muscle efficiency of 0.18 rather than 0.23 should be used to calculate the flight costs of birds in the size range of starlings (approximately 0.1 kg) if Pmet is calculated from Pmech derived from aerodynamic models.

Atrial natriuretic peptide mediated polyuria: pathogenesis of polyhydramnios in the recipient twin of twin-twin transfusion syndrome

We studied the role of atrial natriuretic peptide (ANP) in the pathophysiology of polyhydramnios in monochorionic (MC) twins with and without twin-twin transfusion syndrome (TTTS). Matched maternal, fetal blood samples and amniotic fluids (AF) were obtained in utero (n=12) and at birth (n=20) from MC twins with TTTS. Blood and amniotic fluid samples were also collected from non-TTTS MC twin pairs in utero (n=6) and at birth (n=20). In both groups cellular localization of ANP in the fetal kidney and heart was performed using anti ANP rabbit polyclonal antibody. Concentrations of ANP in pg/ml were determined by radioimmunoassay.In recipient fetuses, ANP levels were higher than the donors both in utero (P< 0.001) and at birth (P< 0.001). No such differences were found between the non-TTTS twins. In the TTTS group maternal ANP levels were lower than the non-TTTS group (P< 0.05). A linear relationship was found between fetal ANP levels and the AF volumes removed at fetal blood sampling (r(2)=0.68;P< 0.01, n=12). ANP was localized predominantly to the cytoplasm of the distal convoluted tubules of the fetal kidney and heart, and the intensity of immunostaining for ANP in kidney and heart were markedly greater in the recipient than the donor twin. No such differences were found between the twin pairs. These data suggest that polyhdramnios in the recipient twin occurs as a consequence of ANP mediated increase in fetal urine output and raises the possibility of direct fetal therapy with ANP blocking agents.

Gain of 1q and loss of 22 are the most common changes detected by comparative genomic hybridisation in paediatric ependymoma

Ependymomas are the third most common brain tumour in the paediatric population. Although cytogenetic and molecular analyses have pinpointed deletions of chromosomes 6q, 17, and 22 in a subset of tumours, definitive patterns of genetic aberrations have not been determined. In the present study, we analysed 40 ependymomas from paediatric patients for genomic loss or gain using comparative genomic hybridisation (CGH). Eighteen of the tumours (45%) had no detectable regions of imbalance. In the remaining cases, the most common copy number aberrations were loss of 22 (25% of tumours) and gain of 1q (20%). Three regions of high copy number amplification were noted at 1q24-31 (three cases), 8q21-23 (two cases), and 9p (one case). Although there was no association with the loss or gain of any chromosome arm or with benign versus anaplastic histologic characteristics, the incidence of gain of 7q and 9p and loss of 17 and 22 was significantly higher in recurrent versus primary tumours. This study has identified a number of chromosomal regions that may contain candidate genes involved in the development of different subgroups of ependymoma.

Placental regulation of insulin-like growth factor axis in monochorionic twins with chronic twin-twin transfusion syndrome

To test the hypothesis that severe growth restriction (intrauterine growth retardation) in donor twins with chronic twin-twin transfusion syndrome (TTTS), a common complication of monochorionic twin pregnancy, is due to an aberration in the insulin-like growth factor (IGF) axis, we studied 25 sets of monochorionic twins with (n = 13) and without (n = 12) TTTS. Maternal and cord blood samples were collected at birth and analyzed for IGF-I, IGF-II, IGF-binding protein-1 (IGFBP-1), and IGFBP-1 phosphorylation status. Fetal IGF-II levels in the recipient twins with TTTS were higher than those in the donor twins (829 +/- 45 vs. 543 +/- 60 ng/mL; P < 0.001), but were comparable with those in the non-TTTS twin pairs. IGF-I levels in recipient and donor twin pairs were similar. The total IGFBP-1 concentration was higher in the donor twins than in the recipients (1153 +/- 296 vs. 419 +/- 108 ng/mL; P < 0.001) and non-TTTS twin pairs (P < 0.01). The percent less phosphorylated IGFBP-1 was higher in the recipients than in the donor twins (P < 0.05). There were no differences in IGF-I, IGF-II, and IGFBP-1 levels between non-TTTS twin pairs. Maternal levels of IGFs were comparable in the two groups. In the TTTS group, fetal birth weight gave a positive correlation with serum IGF-II levels (y = 0.25x + 361.1; r = 0.47; P < 0.05), and a negative association with IGFBP-1 levels (y = -0.72x + 1593.6; r = 0.58; P < 0.01). Our data argue against intertwin transfusion as the cause of intrauterine growth retardation in the donor twin and provide evidence that the placenta is the key regulator of the fetal IGF axis, especially when fetal genotype and maternal environments are similar.

Experience with a clinical guideline for the treatment of ventilator-associated pneumonia

OBJECTIVE

To evaluate a clinical guideline for the treatment of ventilator-associated pneumonia.

DESIGN

Prospective before-and-after study design.

SETTING

A medical intensive care unit from a university-affiliated, urban teaching hospital.

PATIENTS

Between April 1999 and January 2000, 102 patients were prospectively evaluated.

INTERVENTIONS

Prospective patient surveillance, data collection, and implementation of an antimicrobial guideline for the treatment of ventilator-associated pneumonia.

MEASUREMENTS AND MAIN RESULTS

The main outcome evaluated was the initial administration of adequate antimicrobial treatment as determined by respiratory tract cultures. Secondary outcomes evaluated included the duration of antimicrobial treatment for ventilator-associated pneumonia, hospital mortality, intensive care unit and hospital lengths of stay, and the occurrence of a second episode of ventilator-associated pneumonia. Fifty consecutive patients with ventilator-associated pneumonia were evaluated in the before period and 52 consecutive patients with ventilator-associated pneumonia were evaluated in the after period. Severity of illness using Acute Physiology and Chronic Health Evaluation II (25.8 +/- 5.7 vs. 25.4 +/- 8.1, p =.798) and the clinical pulmonary infection scores (6.6 +/- 1.0 vs. 6.9 +/- 1.2, p =.105) were similar for patients during the two treatment periods. The initial administration of adequate antimicrobial treatment was statistically greater during the after period compared with the before period (94.2% vs. 48.0%, p <.001). The duration of antimicrobial treatment was statistically shorter during the after period compared with the before period (8.6 +/- 5.1 days vs. 14.8 +/- 8.1 days, p <.001). A second episode of ventilator-associated pneumonia occurred statistically less often among patients in the after period (7.7% vs. 24.0%, p =.030).

CONCLUSIONS

The application of a clinical guideline for the treatment of ventilator-associated pneumonia can increase the initial administration of adequate antimicrobial treatment and decrease the overall duration of antibiotic treatment. These findings suggest that similar types of guidelines employing local microbiological data can be used to improve overall antibiotic utilization for the treatment of ventilator-associated pneumonia.

Evaluation of an inspiratory muscle trainer in healthy humans

The Powerbreathe is an inspiratory muscle trainer promoted as improving inspiratory muscle strength (and consequently exercise performance) in athletes and patients with respiratory disease. No published evidence supports its efficacy. We performed a prospective randomized controlled study in which 12 normal subjects received either Powerbreathe training or sham training for a 6-week period. The primary outcome measure was diaphragm strength evaluated as twitch transdiaphragmatic pressure (Tw Pdi) but secondary outcome measures were provided by full respiratory muscle assessment and cardiopulmonary exercise testing. An advantage to training was observed when outcome was assessed by maximal static inspiratory mouth pressure (mean advantage 14.5 cm H2O, 95% CI 2.2-26.9 cm H2O, P=0.025). However. no significant difference was observed between the groups in any other parameter. In particular the deltaTw Pdi was not different between groups (mean 'advantage' 0.7 cmH2O, 95% CI- 7.0+/-5.5 cmH2O, P=0.8). The continued sale and use of the Powerbreathe device is not justified by our data. A sample size calculation showed that 234 subjects would need to be randomized to definitively refute the hypothesis that Powerbreathe improves Tw Pdi and we argue that such a study is required.

Molecular characterization of the surface layer proteins from Clostridium difficile

Many bacteria express a surface-exposed proteinaceous layer, termed the S-layer, which forms a regular two-dimensional array visible by electron microscopy. Clostridium difficile is unusual in expressing two S-layer proteins (SLPs), which are of varying size in a number of strains. In an approach combining molecular biology with mass spectrometric sequencing strategies, we have identified the structural gene (slpA) for the S-layer from three strains of C. difficile. Both proteins are derived from a common precursor, and processing involves the removal of a signal peptide and a second cleavage to release the two mature SLPs. To our knowledge, this is the first example in which two SLPs have been shown to derive from a single gene product through post-translational processing, rather than from the expression of separate genes. The higher molecular weight (MW) SLP is highly conserved among the three strains, whereas the lower MW SLP shows considerable sequence diversity, reflecting the results from Western blotting. The high-MW SLP shows weak homology to N-acetyl muramoyl-L-alanine amidase from Bacillus subtilis, and both the native SLP from C. difficile and a recombinant protein expressed in Escherichia coli were found to display amidase activity by zymography. The high-MW SLPs showed evidence of glycosylation, whereas the lower MW proteins did not. A family of genes with sequence homology to the amidase domain of the high-MW SLP was identified in the C. difficile strain 630 genome, some of which are located in the same region of the genome as slpA and were shown by reverse transcription-polymerase chain reaction (RT-PCR) analysis to be transcribed.

A herpes simplex virus type 1 gamma34.5 second-site suppressor mutant that exhibits enhanced growth in cultured glioblastoma cells is severely attenuated in animals

We describe here the neurovirulence properties of a herpes simplex virus type 1 gamma34.5 second-site suppressor mutant. gamma34.5 mutants are nonneurovirulent in animals and fail to grow in a variety of cultured cells due to a block at the level of protein synthesis. Extragenic suppressors with restored capacity to replicate in cells that normally do not support the growth of the parental gamma34.5 deletion mutant have been isolated. Although the suppressor virus reacquires the ability to grow in nonpermissive cultured cells, it remains severely attenuated in mice and is indistinguishable from the mutant gamma34.5 parent virus at the doses investigated. Repairing the gamma34.5 mutation in the suppressor mutant restores neurovirulence to wild-type levels. These studies illustrate that (i) the protein synthesis and neurovirulence defects observed in gamma34.5 mutant viruses can be genetically separated by an extragenic mutation at another site in the viral chromosome; (ii) the extragenic suppressor mutation does not affect neurovirulence; and (iii) the attenuated gamma34.5 mutant, which replicates poorly in many cell types, can be modified by genetic selection to generate a nonpathogenic variant that regains the ability to grow robustly in a nonpermissive glioblastoma cell line. As this gamma34.5 second-site suppressor variant is attenuated and replicates vigorously in neoplastic cells, it may have potential as a replication-competent, viral antitumor agent.

Discordant Fetal Leptin Levels in Monochorionic Twins with Chronic Midtrimester Twin–Twin Transfusion Syndrome

The objective of this study was to determine the plasma leptin concentrations in monochorionic twin fetuses with and without twin-twin transfusion syndrome (TTTS). Paired maternal and fetal blood samples were obtained at birth from monochorionic twin pregnancies complicated with (n=12) or without TTTS (n=12). Amniotic fluid samples were also collected from twin pairs at amnioreduction and/or fetal blood sampling in utero. Plasma and amniotic fluid leptin concentrations were measured by radio-immunoassay. Fetal leptin levels in the growth-restricted donor were lower than the recipient twin of the TTTS group (Delta mean 3.7; CI 2.6 to 4.7 ng/ml; P< 0.001). Fetal leptin levels were comparable between non-TTTS twin pairs (Delta mean 0.9; CI 0.1 to 1.4 ng/ml; P=0.10) and recipient twins of TTTS (P=NS). Maternal plasma concentrations of leptin were comparable between the two groups and were higher than the fetal levels. There was a positive association between cord leptin levels and birthweight of twin pairs (y=0.002x-0.37; r=0.58; P< 0.01; n=48). A significant positive relation was also found between delta leptin levels and percentage discordance in birthweight in the TTTS group (y=0.25x-2.21; r=0.82; P< 0.001, n=12). In conclusion, leptin levels in the recipient twins were three times higher than their growth restricted donor twins. However further studies are warranted to elucidate the underlying mechanism.

Patient education in pain control

Patients' concerns about reporting pain and using analgesics have been cited as major contributors to the problem of inadequate pain management. The purpose of this paper is to describe a program of research in which we have focused on these patient concerns, or as we refer to them, "patient-related barriers to pain management." We present a summary of descriptive studies on this topic, describe educational interventions that have been tested, and suggest future avenues of research and practice.

Fetal leptin influences birth weight in twins with discordant growth

The objective of this study was to determine the plasma leptin concentrations in twin pregnancies in relation to chorionicity and discordant fetal growth. We studied 53 twin pregnancies of which 26 had growth discordance of > or =20% and 27 were concordant for growth (discordance of < or =10%). Paired maternal and fetal blood samples were obtained at birth. Plasma leptin concentrations were measured by RIA. In discordant monochorionic pregnancies, fetal plasma leptin concentrations in the intrauterine growth-restricted twins were lower than the co-twins with normal growth (mean difference, 3 ng/mL; 95% CI, 2.2 to 3.3 ng/mL; p < 0.001), whereas no such differences were present between concordant monochorionic twin pairs (mean difference, 0.1 ng/mL; 95% CI, -0.2 to 0.5 ng/mL; NS). Similarly, fetal plasma leptin concentrations in appropriate-for-gestational-age twins were higher than in the intrauterine growth-restricted twins of the discordant dichorionic pregnancies (mean difference, 2.4 ng/mL; 95% CI, 1.8 to 3.1 ng/mL; p < 0.001). No such differences were present between the concordant dichorionic twin pairs (mean difference, 0.2 ng/mL; 95% CI, -0.1 to 0.5 ng/mL; NS). Maternal plasma leptin concentrations were comparable among all four groups and were higher than the fetal levels. Fetal plasma leptin concentrations of the intrauterine growth-restricted twins of discordant monochorionic and dichorionic pregnancies were comparable. There was a positive association between cord plasma leptin concentrations and the birth weight of twin pairs (y = 0.002x - 0.32; r = 0.63; p < 0.001; n = 106). A significant positive association was also found between percent differences in birth weight and fetal delta plasma leptin concentrations of the discordant monochorionic and dichorionic twin pairs (y = 0.057x + 0.93; r = 0.60; p < 0.001, n = 26). In conclusion, irrespective of chorionicity, plasma leptin concentrations in intrauterine growth-restricted twins were 2-fold lower than their co-twins with normal growth. These differences may be attributed to placental factors.

Identification of extensive genomic loss and gain by comparative genomic hybridisation in malignant astrocytoma in children and young adults

Although astrocytomas are the most common central nervous system tumours in all age groups, there is substantial evidence that tumours arising in young patients (< 25 years of age) do not have the same genetic abnormalities that are characteristic of tumours in older patients. Furthermore, novel, consistent changes have not been identified in astrocytomas in children and young adults. We analysed 13 malignant astrocytomas from young patients using comparative genomic hybridisation. Regions of genomic imbalance were identified in 10 cases. The most common recurrent copy number aberrations were loss of 16p (54% of cases), 17p (38%), 19p (38%), and 22 (38%) and gain on 2q (38%), 12q (38%), 13 (38%), 4q (31%), 5q (31%), and 8q (31%). Seven regions of high copy number amplification were observed at 8q21-22 (three cases), 7q22-23 (two cases), and 1p21-22, 2q22, 12q13-pter, 12q15-21, and 13q11-14 (one case each). This study provides evidence of new characteristic chromosomal imbalances from which potential candidate genes involved in the development of malignant astrocytoma in children and young adults may be identified.

Prenatal genotyping for the RhD blood group antigen: considerations in developing an accurate test

Experience performing prenatal genotyping for RHD has shown that consideration must be given to developing a molecular test capable of detecting recombination/gene conversion events involving the RHD and RHCE genes that can lead to erroneous results. Out of 50 prenatal RHD tests performed over the past 5 years, four samples were encountered that gave false-positive results. In only one of the tests, incorrect results were issued to the physician. In the other three instances, the erroneous nature of the test results was revealed through the analysis of multiple regions of the RHD gene and, more importantly, because the mother, and sometimes the father, were tested in parallel with the fetus. In an extension of the observations obtained from the prenatal testing program, a large panel of RhD-negative blood donors were subjected to molecular analysis of the RHD gene. Of 1,183 donors screened, 187 were found to phenotype as RhD negative. Of the 187 donors confirmed RhD negative serologically, 22 (11.8%) were found to retain remnants of the RHD gene that, depending upon the characteristics of the molecular assay performed, could lead to a false-positive result in a genotyping assay. On the basis of the experience presented here, it is recommended that any molecular RHD assay include an analysis of multiple areas of the RHD gene so as to allow for the detection of recombination/gene conversion events between the RHD and RHCE genes. Moreover, it is strongly recommended that the mother (at a minimum) and father be subjected to molecular analysis simultaneously with the fetus to confirm that the known phenotypes of the parent(s) are consistent with their respective genotypes.

Pulmonary embolism: comparison of gadolinium-enhanced MR angiography with contrast-enhanced spiral CT in a porcine model

RATIONALE AND OBJECTIVES

The purpose of this study was to compare gadolinium-enhanced magnetic resonance (MR) angiography with contrast material-enhanced computed tomography (CT) for the detection of small (4-5-mm) pulmonary emboli (PE), with a methacrylate cast of the porcine pulmonary vasculature used as the diagnostic standard.

MATERIALS AND METHODS

In 15 anesthetized juvenile pigs, colored methacrylate beads (5.2 and 3.8 mm diameter-the size of segmental and subsegmental emboli in humans) were injected via the left external jugular vein. After embolization, MR angiographic and CT images were obtained. The pigs were killed, and the pulmonary arterial tree was cast in clear methacrylate, allowing direct visualization of emboli. Three readers reviewed CT and MR angiographic images independently and in random order.

RESULTS

Forty-nine separate embolic sites were included in the statistical analysis. The mean sensitivity (and 95% confidence intervals) for CT and MR angiography, respectively, were 76% (68%-82%) and 82% (75%-88%) (P > .05); the mean positive predictive values, 92% (85%-96%) and 94% (88%-97%) (P > .05). In this porcine model, PE were usually seen as parenchymal perfusion defects (98%) with MR angiography and as occlusive emboli (100%) with CT.

CONCLUSION

MR angiography is as sensitive as CT for the detection of small PE in a porcine model.

Genes or placenta as modulator of fetal growth: evidence from the insulin-like growth factor axis in twins with discordant growth

To determine whether fetal growth is regulated by placental and/or fetal factors, we measured maternal and fetal concentrations of insulin-like growth factor-I (IGF-I), IGF-II and insulin-like growth factor binding protein-1 (IGFBP-1) (total and non-phosphorylated) in dichorionic (DC) and monochorionic (MC) twins with (DC, n = 13; MC, n = 12) or without (DC, n = 13; MC, n = 12) discordant birth weight. In the discordant MC pregnancy, growth-restricted (IUGR) twins had lower IGF-II concentrations (P < 0.001) but similar IGF-I concentrations compared to the appropriate for gestational age(AGA) co-twin. The differences in IGF-II concentrations showed a positive association with percentage birth weight discordance (r = 0.60; P < 0.05) in MC twins. In contrast, IUGR DC twins had lower IGF-I concentrations (P < 0.05) but similar IGF-II concentrations compared to the AGA co-twins. There was a positive correlation between IGF-I concentrations and birth weight (r = 0.47; P < 0.05) in DC twins. Total IGFBP-1 concentrations were higher in both MC and DC IUGR twins (P < 0.05) compared to AGA twins. A negative association was found between total IGFBP-1 concentrations and birthweight of both MC (r = 0.47; P < 0.05) and DC (r = 0.58; P < 0.01) twins. No such differences in IGF concentrations were found between concordant MC and DC twin pairs. The maternal IGF concentrations were comparable between the MC and DC groups. These data suggest that growth discordances of twins exposed to the same maternal environment may be due to variations in either IGF-I or IGF-II/IGFBP-1, depending upon the functioning of the placenta.

Explaining retrospective reports of symptoms in patients undergoing chemotherapy: anxiety, initial symptom experience, and posttreatment symptoms

This study evaluated different perspectives on the relationship of trait anxiety to symptom report. Baseline trait anxiety was related to (a) initial symptoms reported 2 days after beginning chemotherapy, (b) posttreatment symptoms reported 2 days after cessation of medication, and (c) retrospective reports of initial symptoms (made concurrently with posttreatment reports). Associations were significant for vague psychophysiological symptoms but not for concrete visible symptoms. Path models indicated that the relationship of anxiety to retrospective report of vague symptoms was due to both enhanced encoding and facilitated recall of symptoms. Further analyses revealed, however, that this relationship reflects symptoms stability rather than anxiety-related differences in attention. Anxious and nonanxious patients appear to be equally accurate in their retrospective report of symptoms.

Erythropoietin in monochorionic twin pregnancies in relation to twin--twin transfusion syndrome

Fetal erythropoietin (Epo) concentrations were studied in monochorionic (MC) twin pregnancies in relation to twin-twin transfusion syndrome (TTTS). Matched maternal and fetal blood samples in utero were obtained from MC twins with TTTS (n = 15) and without TTTS (n = 6). In a second group of five sets of twin pairs with or without TTTS, immunolocalization of Epo was performed in archived paraffin wax sections of liver and kidney collected at autopsy. Epo was measured using a chemiluminescence assay and expressed as gestation independent Z-scores and given as mean +/- 95% confidence intervals (CI). Fetal Epo concentrations in utero were higher in MC twins with TTTS than the non-TTTS as a group (P < 0.001). There was no difference in Epo concentrations between TTTS and non-TTTS twin pairs. Fetal Epo concentrations were correlated with pO(2) in the recipient (r = 0.64; P < 0.01), donor (r = 0.64; P < 0.01) and control twins (r = 0.76; P < 0.01). Immunostaining of the fetal kidney localized Epo primarily to the cytoplasm of the proximal convoluted tubules. The intensity of staining in the kidney and liver was comparable between TTTS and non-TTTS twin pairs. Fetal Epo concentrations were higher in the TTTS than non-TTTS twin pairs and were correlated with the degree of hypoxaemia. However, Epo concentrations were comparable between donor and recipient twins, perhaps due to similar production rather than inter-twin transfusion of blood.

Iron metabolism in monochorionic twin pregnancies in relation to twin--twin transfusion syndrome

Fetal iron metabolism was investigated in monochorionic (MC) twin pregnancies in relation to twin-twin transfusion syndrome (TTTS). Matched maternal and fetal blood samples were obtained both in utero and at birth from MC twins with TTTS (n = 23) and without TTTS (n = 18). In a second group of 30 twin pairs (15 with and 15 without TTTS), liver iron content was assessed by using archived paraffin wax-embedded blocks. Serum ferritin was determined by radioimmunoassay and values are given as gestation independent Z-scores and expressed as mean with 95% confidence intervals. Ferritin concentrations in the recipients were higher than in the donors both in utero (P < 0.01) and at birth (P < 0.01). Fetal serum ferritin in non-TTTS twins were similar to the recipient twins but higher than the donor twins (P < 0.05). A significant association was found between ferritin concentrations, the total red blood cell count and haemoglobin in the TTTS twin pairs (P < 0.01) and the non-TTTS twins as a group (P < 0.01). The total stainable liver iron was comparable between twin pairs in the TTTS and non-TTTS groups. This study fails to provide evidence of iron overload in the recipient and depletion in the donor twins and, thereby, questions the validity of the conventional theory of inter-twin transfusion as the cause of TTTS.

The impact of the introduction of a rapid D-dimer assay on the diagnostic evaluation of suspected pulmonary embolism

BACKGROUND

Rapid D-dimer assays are being used in the diagnostic evaluation of suspected pulmonary embolism (PE). Although this hypothesis is anticipated to decrease the use of ventilation-perfusion (VQ) scans and other diagnostic tests for PE, it has not been tested in a "real-world" environment.

SUBJECTS AND METHODS

A randomized prospective trial was conducted on 470 of the 5390 enrolled patients aged 60 years and older who had previously undergone any diagnostic tests for PE at an urban teaching hospital. The use of D-dimer as part of the diagnostic evaluation for PE was promulgated in the 2 randomly chosen intervention firms. The remaining 2 firms served as controls.

MAIN OUTCOME MEASURES

The number of VQ scans, spiral computed tomographic scans, and pulmonary angiograms performed. Secondary outcomes included mortality and thromboembolic or bleeding events during 3 months of follow-up.

RESULTS

Of the 470 inpatients who underwent evaluation for PE on a per PE workup basis, fewer VQ scans were performed in the intervention firms (63.8% vs 81.3%; P<.01). However, the number of patients evaluated for PE nearly doubled in the intervention firms (304 vs 166; P<.01), so that more VQ scans were performed in the intervention than in the control firms (194 vs 135; P<.01). Ninety-four patients from the control firms and 160 patients from the intervention firms were diagnosed and treated for venous thromboembolic disease (P<.01). There were no differences in secondary outcomes during the 3-month follow-up.

CONCLUSIONS

The introduction of a rapid D-dimer assay increased the number of VQ scans performed because the number of patients screened for PE increased. A larger number of patients in the intervention firms were diagnosed as having venous thromboembolic disease (PE and/or deep vein thrombosis). There were no perceived changes in mortality or venous thromboembolic events during the 3-month follow-up.

ENCORE: the effect of nutrient enrichment on coral reefs. Synthesis of results and conclusions

Coral reef degradation resulting from nutrient enrichment of coastal waters is of increasing global concern. Although effects of nutrients on coral reef organisms have been demonstrated in the laboratory, there is little direct evidence of nutrient effects on coral reef biota in situ. The ENCORE experiment investigated responses of coral reef organisms and processes to controlled additions of dissolved inorganic nitrogen (N) and/or phosphorus (P) on an offshore reef (One Tree Island) at the southern end of the Great Barrier Reef, Australia. A multi-disciplinary team assessed a variety of factors focusing on nutrient dynamics and biotic responses. A controlled and replicated experiment was conducted over two years using twelve small patch reefs ponded at low tide by a coral rim. Treatments included three control reefs (no nutrient addition) and three + N reefs (NH4Cl added), three + P reefs (KH2PO4 added), and three + N + P reefs. Nutrients were added as pulses at each low tide (ca twice per day) by remotely operated units. There were two phases of nutrient additions. During the initial, low-loading phase of the experiment nutrient pulses (mean dose = 11.5 microM NH4+; 2.3 microM PO4(-3)) rapidly declined, reaching near-background levels (mean = 0.9 microM NH4+; 0.5 microM PO4(-3)) within 2-3 h. A variety of biotic processes, assessed over a year during this initial nutrient loading phase, were not significantly affected, with the exception of coral reproduction, which was affected in all nutrient treatments. In Acropora longicyathus and A. aspera, fewer successfully developed embryos were formed, and in A. longicyathus fertilization rates and lipid levels decreased. In the second, high-loading, phase of ENCORE an increased nutrient dosage (mean dose = 36.2 microM NH4+; 5.1 microM PO4(-3)) declining to means of 11.3 microM NH4+ and 2.4 microM PO4(-3) at the end of low tide) was used for a further year, and a variety of significant biotic responses occurred. Encrusting algae incorporated virtually none of the added nutrients. Organisms containing endosymbiotic zooxanthellae (corals and giant clams) assimilated dissolved nutrients rapidly and were responsive to added nutrients. Coral mortality, not detected during the initial low-loading phase, became evident with increased nutrient dosage, particularly in Pocillopora damicornis. Nitrogen additions stunted coral growth, and phosphorus additions had a variable effect. Coral calcification rate and linear extension increased in the presence of added phosphorus but skeletal density was reduced, making corals more susceptible to breakage. Settlement of all coral larvae was reduced in nitrogen treatments, yet settlement of larvae from brooded species was enhanced in phosphorus treatments. Recruitment of stomatopods, benthic crustaceans living in coral rubble, was reduced in nitrogen and nitrogen plus phosphorus treatments. Grazing rates and reproductive effort of various fish species were not affected by the nutrient treatments. Microbial nitrogen transformations in sediments were responsive to nutrient loading with nitrogen fixation significantly increased in phosphorus treatments and denitrification increased in all treatments to which nitrogen had been added. Rates of bioerosion and grazing showed no significant effects of added nutrients. ENCORE has shown that reef organisms and processes investigated in situ were impacted by elevated nutrients. Impacts were dependent on dose level, whether nitrogen and/or phosphorus were elevated and were often species-specific. The impacts were generally sub-lethal and subtle and the treated reefs at the end of the experiment were visually similar to control reefs. Rapid nutrient uptake indicates that nutrient concentrations alone are not adequate to assess nutrient condition of reefs. Sensitive and quantifiable biological indicators need to be developed for coral reef ecosystems. The potential bioindicators identified in ENCORE should be tested in future research on coral reef/nutrient interactions. Synergistic and cumulative effects of elevated nutrients and other environmental parameters, comparative studies of intact vs. disturbed reefs, offshore vs. inshore reefs, or the ability of a nutrient-stressed reef to respond to natural disturbances require elucidation. An expanded understanding of coral reef responses to anthropogenic impacts is necessary, particularly regarding the subtle, sub-lethal effects detected in the ENCORE studies.

Relationships between certification and job perceptions of oncology nurses

PURPOSE/OBJECTIVES

To explore relationships between oncology nursing certification and oncology nurses' job perceptions.

DESIGN

Descriptive, correlational.

SETTING

Questionnaire mailed to homes of Oncology Nursing Society (ONS) members.

SAMPLE

703 certified and 514 noncertified ONS members (N = 1,217; 50% response rate).

METHODS

Data were collected using survey methods and grouped by respondents' certification status for statistical analysis.

MAIN RESEARCH VARIABLES

Certification, group cohesion, organizational commitment, and job satisfaction.

FINDINGS

Certification was weakly correlated with cohesion, commitment, and satisfaction. Work setting, rather than certification, accounted for differences in job perceptions. Job perceptions were most positive in settings characterized by a high percentage of patients with cancer (> 75%), a high percentage of RNs (> or = 80%), and monetary support for continuing education.

CONCLUSIONS

The hypothesis that oncology nurses' certification status is associated with job perceptions that are valued by employers was not supported.

IMPLICATIONS FOR NURSING PRACTICE

Nurses' job perceptions have been linked to control over nursing practice and participation in organizational and clinical decision making. Managerial strategies that empower certified nurses to practice with more autonomy and participate in decisions that affect patient care should be emphasized.

spe-29 encodes a small predicted membrane protein required for the initiation of sperm activation in Caenorhabditis elegans

Caenorhabditis elegans spermatids complete a dramatic morphogenesis to crawling spermatozoa in the absence of an actin- or tubulin-based cytoskeleton and without synthesizing new gene products. Mutations in three genes (spe-8, spe-12, and spe-27) prevent the initiation of this morphogenesis, termed activation. Males with mutations in any of these genes are fertile. By contrast, mutant hermaphrodites are self-sterile when unmated due to a failure in spermatid activation. Intriguingly, mutant hermaphrodites form functional spermatozoa and become self-fertile upon mating, suggesting that spermatids can be activated by male seminal fluid. Here we describe a mutation in a fourth gene, spe-29, which mimics the phenotype of spe-8, spe-12, and spe-27 mutants. spe-29 sperm are defective in the initiation of hermaphrodite sperm activation, yet they maintain the ability to complete the morphogenetic rearrangements that follow. Mutant alleles of spe-12, spe-27, and spe-29 exhibit genetic interactions that suggest that the wild-type products of these genes function in a common signaling pathway to initiate sperm activation. We have identified the spe-29 gene, which is expressed specifically in the sperm-producing germ line and is predicted to encode a small, novel transmembrane protein.

Discordant amino acid profiles in monochorionic twins with twin-twin transfusion syndrome

To test the hypothesis that discordant growth in monochorionic (MC) twins occurs at least in part due to disparity in placental amino acid transporter function, we measured plasma amino acid levels by HPLC in maternal and fetal blood samples collected at birth from gestational age matched twins with (n = 12) and without (n = 12) twin-twin transfusion syndrome (TTTS). In the donor twin, fetal plasma concentrations and feto-maternal ratios of five essential amino acids-valine (p < 0.001), leucine (p < 0.001), iso-leucine (p < 0.05), histidine (p < 0.001) and L-arginine (p < 0. 001)-were lower than the recipient and non-TTTS twin pairs. Fetal concentrations of the nonessential amino acids taurine (p < 0.001), serine (p < 0.01), glycine (p < 0.001) and tyrosine (p < 0.05) were also markedly lower in the donor than the recipient and non-TTTS twin pairs. In contrast, the fetal alanine level in the donor twin was higher than the recipient (664 +/- 64 versus 396 +/- 23 microM; p < 0.001) and the non-TTTS twin pairs (p < 0.01). No such differences between amino acid profiles in non-TTTS MC twin pairs were found. Maternal plasma amino acid levels between TTTS and non-TTTS groups were comparable. This study provides the first evidence that certain amino acids in the donor twin of chronic TTTS differ significantly from those of the co-twin while others were comparable between twin pairs. These data, therefore, argue against inter-twin transfusion as the sole cause of growth restriction of the donor twin and suggests instead that impaired placental transport of amino acids may be a likely mechanism.

Inadequate treatment of nosocomial infections is associated with certain empiric antibiotic choices

OBJECTIVE

The purpose of this study was to determine the impact of scheduled changes of antibiotic classes, used for the empirical treatment of suspected or documented Gram-negative bacterial infections, on the occurrence of inadequate antimicrobial treatment of nosocomial infections.

DESIGN

Prospective observational study.

SETTING

Medical (19-bed) and surgical (18-bed) intensive care units in an urban teaching hospital.

PATIENTS

A total of 3,668 patients requiring intensive care unit admission were prospectively evaluated during three consecutive time periods.

INTERVENTIONS

During each time period, one antibiotic class was selected for the empirical treatment of Gram-negative bacterial infections as follows: time period 1 (baseline period) (1,323 patients), ceftazidime; time period 2 (1,243 patients), ciprofloxacin; and time period 3 (1,102 patients), cefepime.

MEASUREMENTS AND MAIN RESULTS

The overall administration of inadequate antimicrobial treatment for nosocomial infections decreased during the course of the study (6.1%, 4.7%, and 4.5%; p = .15). This was primarily because of a statistically significant decrease in the administration of inadequate antibiotic treatment for Gram-negative bacterial infections (4.4%, 2.1%, and 1.6%; p < .001). There were no statistically significant differences in the overall hospital mortality rate among the three time periods (15.6%, 16.4%, and 16.2%; p = .828) despite a significant increase in severity of illness as measured with Acute Physiology and Chronic Health Evaluation (APACHE) II scores (15.3 +/- 7.6, 15.7 +/- 8.0, and 20.7 +/- 8.6; p < .001). The hospital mortality rate decreased significantly during time period 3 (20.6%) compared with time period 1 (28.4%; p < .001) and time period 2 (29.5%; p < .001) for patients with an APACHE II score > or = 15.

CONCLUSIONS

These data suggest that scheduled changes of antibiotic classes for the empirical treatment of Gram-negative bacterial infections can reduce the occurrence of inadequate antibiotic treatment for nosocomial infections. Reducing inadequate antibiotic administration may improve the outcomes of critically ill patients with APACHE II scores > or = 15.

An individualized intervention to overcome patient-related barriers to pain management in women with gynecologic cancers

Concerns about reporting pain and using analgesics ultimately can contribute to poor pain management for many individuals. A nursing intervention to address these "patient-related barriers" was developed based on Johnson's self-regulation theory. The purpose of this pilot study was to determine whether provision of individually tailored sensory and coping information about analgesic side effects and specific information to counter misconceptions would enhance pain management in a sample of 43 women with gynecologic cancers. It was hypothesized that at 1-month post-test and 2-month follow-up, those subjects randomized to the information condition would (a) have lower barriers scores; (b) use more adequate analgesic medication; (c) have lower analgesic side effect scores; (d) have lower pain intensity scores; and (e) experience less pain interference with life and better overall quality of life compared to those in the care-as-usual control group. There was no main effect for group on any of the dependent variables. Rather, all women reported a decrease in barriers between baseline and 2-month follow-up (p<.05); all subjects experienced a decrease in pain interference with life scores between baseline and 1-month post-test (p<.05); and there was a significant shift of women from unacceptable pain management at baseline to acceptable pain management at 1-month post-test (p<.05). In addition, the majority of women reported that the intervention contained novel and useful information that helped them to feel more comfortable taking pain medication, to be less concerned about addiction, and helped them talk more openly about pain with a doctor or nurse.

The choice of embryo transfer catheter affects embryo implantation after IVF

OBJECTIVE

Comparison of two transfer catheters in an IVF program.

DESIGN

Prospective, randomized clinical study.

SETTING

A private tertiary care center for ART.

PATIENT(S)

66 patients < 38 years of age undergoing IVF and/or ICSI.

INTERVENTION(S)

Patients were randomly assigned to undergo ET using the Tomcat catheter (n = 32) or the TDT catheter (n = 34).

MAIN OUTCOME MEASURE(S)

Primary outcome measures were implantation and pregnancy rates. Secondary outcome measures were contamination with blood and/or mucus on the tip of the catheter, cramping or patient discomfort, and time required to complete ET.

RESULT(S)

Use of the Tomcat catheter resulted in significantly higher implantation (25.2% vs. 8.4%) and clinical pregnancy rates (47% vs. 14.7%) compared with the TDT catheter. All secondary outcome measures were similar for both catheters.

CONCLUSION(S)

The choice of ET catheter may affect the success of IVF-ET cycles. Use of the Tomcat catheter compared with the TDT catheter seems to result in significantly better efficiency of the ET procedure and is more cost effective.