A hookworm allergen which strongly resembles calreticulin

Immmoglobulin E-rich plasma from patients from Papua New Guinea infected with Necator americanus has been used to probe an adult N. americanus cDNA library for the presence of hookworm allergens. Using this approach, one hookworm allergen has been identified as calreticulin, which was subsequently expressed in Escherichia coli. Little serological cross reactivity was seen between the recombinant calreticulins of this hookworm and its host. Prospective roles for hookworm calreticulin in the host-parasite relationship are discussed in depth.

General practice and the care of children with HIV infection: 6 month prospective interview study

OBJECTIVES

To describe the use of primary care services by children infected with HIV and to explore the attitudes of their parents to the role of general practitioners in their children's care.

DESIGN

A 6 month prospective study. Quantitative analysis of "contact diaries" kept by parents; qualitative analysis of face to face interviews with parents.

PARTICIPANTS

Parents of children receiving care at a regional referral centre in London.

RESULTS

Twenty four families (80% response rate) were recruited to the study. In 19 families the mother was black African. Half the children had been diagnosed with symptomatic HIV infection, half with AIDS. All the children were registered with a general practitioner who knew of the child's HIV infection. In five families there had initially been tensions in their relationship with their general practitioner but by the time of the study all but one family had established at least an "acceptable" relationship. Children with symptomatic HIV infection saw their general practitioner a mean of 7.5 times per patient year; for children with AIDS the figure was 5.8. Parents regarded the paediatric HIV team at the hospital as their primary source of medical care. Three factors constrained their use of general practice: their own anxieties about distinguishing "normal" symptoms from those related to HIV infection; their view that their general practitioner did not feel competent to treat HIV infected children; and their concerns about maintaining confidentiality in the surgery.

CONCLUSIONS

Parents remain oriented towards the paediatric HIV team as their primary source of medical care and use general practice largely for routine prescriptions for their children. Any further development of the general practitioner's role will need to build on existing relationships with specialist providers and take account of parents' concerns.

Interaction of eukaryotic initiation factor eIF4B with the internal ribosome entry site of foot-and-mouth disease virus is independent of the polypyrimidine tract-binding protein

Eukaryotic translation initiation factor 4B (eIF4B) binds directly to the internal ribosome entry site (IRES) of foot-and-mouth disease virus (FMDV). Mutations in all three subdomains of the IRES stem-loop 4 reduce binding of eIF4B and translation efficiency in parallel, indicating that eIF4B is functionally involved in FMDV translation initiation. In reticulocyte lysate devoid of polypyrimidine tract-binding protein (PTB), eIF4B still bound well to the wild-type IRES, even after removal of the major PTB-binding site. In conclusion, the interaction of eIF4B with the FMDV IRES is essential for IRES function but independent of PTB.

Isolation of T-cell antigens by using a recombinant protein library and its application to the identification of novel vaccine candidates against schistosomiasis

We present here a novel approach to identify T-cell antigens from any infectious agent by use of a library of purified recombinant proteins. Essential features of this strategy include (i) a highly efficient cDNA cloning system which negatively selects against nonrecombinant transformants by making use of the bacterial EcoK restriction system, (ii) affinity staining of cDNA clones expressing recombinant proteins, and (iii) a procedure of simultaneous purification of recombinant proteins from large numbers of isolated clones (representing the protein library) in a single step from pools consisting of up to 24 individual clones. The feasibility of the screening system was confirmed by constructing a protein library of the human parasite Schistosoma mansoni. The recombinant antigens of this library were used to stimulate CD4(+) T cells derived from the axillary lymph nodes of mice vaccinated with irradiated cercariae. In initial screening experiments, we detected parasite-specific proliferation and gamma interferon (IFN-gamma) secretion in response to several pools of cDNA clones. Further analysis of one particular pool revealed that only one of its constituents stimulated considerable IFN-gamma secretion by CD4(+) T cells and that the expressed antigen is identical to a small fragment of myosin heavy chain.

Regulation of monocyte survival in vitro by deposited IgG: role of macrophage colony-stimulating factor

IgG deposition at tissue sites characteristically leads to macrophage accumulation and organ injury. Although the mechanism by which deposited IgG induces tissue injury is not known, we have recently demonstrated that deposited IgG stimulates the release of IL-8 and monocyte chemoattractant protein-1 from normal human monocytes, which may drive inflammation. Since IgG also induces macrophage accumulation in these diseases, we hypothesized that deposited IgG protects monocytes from apoptosis. As an in vitro model of the effect of deposited IgG on monocyte survival, monocyte apoptosis was studied after FcgammaR cross-linking. Monocytes cultured on immobilized IgG, which induces FcgammaR cross-linking, were protected from apoptosis, whereas monocytes cultured with equivalent concentrations of F(ab')2 IgG or 50 times higher concentrations of soluble IgG, neither of which induces FcgammaR cross-linking, were not protected. Moreover, this protection was transferable, as supernatants from immobilized IgG-stimulated monocytes protected freshly isolated monocytes from apoptosis and contained functional M-CSF, a known monocyte survival factor. M-CSF mediated the monocyte survival induced by FcgammaR cross-linking, as neutralizing anti-human M-CSF Abs blocked the monocyte protection provided by either immobilized IgG or IgG-stimulated monocyte supernatants. These findings demonstrate a novel mechanism by which deposited IgG targets tissue macrophage accumulation through FcgammaR-mediated M-CSF release. This pathway may play an important role in promoting and potentiating IgG-mediated tissue injury.

Treatment with the antibiotic roxithromycin in patients with acute non-Q-wave coronary syndromes. The final report of the ROXIS Study

AIMS

Mounting evidence suggests infection, specifically Chlamydia pneumoniae, plays a role in atherosclerosis. We tested whether antibiotic treatment with the macrolide roxithromycin improves clinical outcome in patients with acute non-Q-wave coronary syndromes. Preliminary reports revealed a reduction in events in the roxithromycin group at 30 days. We now report the long-term follow-up results.

METHODS AND RESULTS

Sixty-four per cent of the initial 202 patients with unstable angina who were randomly assigned to receive either roxithromycin or placebo for 30 days completed the active treatment period. At day 30, the primary triple and double end-point rates were 9% and 4% in the placebo group compared to 2% and 0% in the roxithromycin group (unadjusted P = 0.032 and 0.058, respectively). The secondary triple and double end-point rates were again higher in the placebo group at day 90 (12.5% and 6.25% vs 4.37% and 0%, unadjusted P = 0.065 and 0.029, respectively), and at day 180 (14.6% and 7.29% vs 8.69% and 2.17%, unadjusted P = 0.259 and 0.17, respectively). Anti-C, pneumoniae IgG titres were unchanged in both groups while C-reactive protein levels decreased in both strategies, with a more significant decrease in the roxithromycin arm (P = 0.03). Elevated C-reactive protein levels predicted the need for revascularization.

CONCLUSIONS

In this pilot trial, roxithromycin appears to extend the clinical benefit of preventing death and re-infarction for at least 6 months after initial treatment.

Cohesion and organization patterns among family members coping with rheumatoid arthritis

The effects of rheumatoid arthritis (RA) on family functioning are described from two perspectives, cohesiveness and organization. These concepts are believed to be essential for assessing levels of family stability following the onset of a life crisis. In this study we characterized the ways in which families organize their daily activities and achieve family cohesiveness. Fifteen families participated in the study. The data showed family members have positive perceptions about their family cohesiveness and organizational behaviors, which were characterized in personal interviews. Families also discussed active and passive coping styles in response to RA. Implications for social work practice and issues for future research are presented.

Hospital intensive care units have to face the market realities of managed care

The ICU is one of the last hospital bastions to face the market realities of managed care. Ellen Beck examines the situation and outlines what some hospitals and health systems are doing to improve outcomes, administrative issues and the experiences of patients and their families.

Government officials redefine use of False Claims Act to combat fraudulent hospital bills

The Dept. of Justice and the Dept. of Health and Human Services Office of Inspector General have issued new guidelines for using the False Claims Act to prosecute hospitals that fraudulently bill Medicare. Ellen Beck explains the changes and why the American Hospital Association calls the more lenient use of the FCA a "positive first step" toward acknowledging that the act is being used improperly.

Multiple virulence determinants of foot-and-mouth disease virus in cell culture

Hypervirulent variants of foot-and-mouth disease virus (FMDV) of serotype C arise upon serial cytolytic or persistent infections in cell culture. A specific mutation in the internal ribosome entry site of persistent FMDV was previously associated with enhanced translation initiation activity that could contribute to the hypervirulent phenotype for BHK-21 cells. Here we report that several hypervirulent FMDV variants arising upon serial cytolytic passage show an invariant internal ribosome entry site but have a number of mutations affecting structural and nonstructural viral proteins. The construction of chimeric type O-type C infectious transcripts has allowed the mapping of a major determinant of hypervirulence to the viral capsid. Tissue culture-adapted FMDV displayed enhanced affinity for heparin, but binding to cell surface heparan sulfate moieties was not required for expression of the hypervirulent phenotype in Chinese hamster ovary (CHO) cells. Virulence was identical or even higher for glycosaminoglycan-deficient CHO cells than for wild-type CHO cells. FMDV variants with decreased affinity for heparin were selected from a high-binding parental population and analyzed. Substitutions associated with decreased heparin binding were located at positions 173 of capsid protein VP3 and 144 of capsid protein VP1. These substitutions had a moderate effect on virulence for BHK-21 cells but completely abrogated infection of CHO cells. The comparative results with several FMDV isolates show that (i) increased affinity for heparin and alterations in cell tropism may be mediated by a number of independent sites on the viral capsid and (ii) the same capsid modifications may have different effects on different cell types.

Hospital compliance on a budget

Community and rural hospitals are among the last to jump aboard the compliance program bandwagon. For many, it boils down to a belief that a plan either is not necessary or not affordable. Ellen Beck profiles the special issues that smaller hospitals face amid government investigations into Medicare/Medicaid billing fraud.

Protein heterogeneity of spinach pullulanase results from the coexistence of interconvertible isomeric forms of the monomeric enzyme

Purified pullulanase (starch-debranching enzyme, R-enzyme, EC 3.2.1. 41) from spinach (Spinacia oleracea L.) chloroplasts separated into at least seven individual enzymically active proteins (isomers, numbered 1-7) on isoelectric focusing or column chromatofocusing. At their isoelectric points (between pH 4.7 and 5.2) these forms were rather stable. At slightly alkaline pH, each converted into the whole set of isomers. PAGE of the purified enzyme under denaturing or non-denaturing conditions resulted in one protein band. When substrate (amylopectin or pullulan) was included in the gel, the native enzyme as well as any of the individual isomers separated into two (sometimes three) bands ('substrate-induced forms', numbered I-III) with different specific activities, dissociation constants of the enzyme-substrate complexes and activation energies. Each substrate-induced form produced the whole set of seven isomers on isoelectric focusing. The specific activity of the total enzyme reflected the relative proportions of the substrate-induced forms. To some extent the relative proportions, as determined by crossed immunoelectrophoresis, could be shifted in favour of the more or the less active forms by reduction with dithiothreitol, and gentle oxidation respectively. Activation by dithiothreitol did not alter the mode of action of the enzyme but only increased the velocity of substrate degradation and extended its activity into the pH range of the chloroplast. As a consequence of isomer interconversion, microheterogeneity could serve to regulate pullulanase activity in a biochemical manner that shares some features with allosteric regulation.

cDNA sequence and heterologous expression of monomeric spinach pullulanase: multiple isomeric forms arise from the same polypeptide

The spinach pullulanase gene was cloned and sequenced using peptide sequences of the purified enzyme as a starting point and employing PCR techniques and cDNA library screening. Its open reading frame codes for a protein of 964 amino acids which represents a precursor of the pullulanase. The N-terminal transit peptide consists of 65 amino acids, and the mature protein, comprising 899 amino acids, has a calculated molecular mass of 99kDa. Pullulanase is a member of the alpha-amylase family. In addition to a characteristic catalytic (beta/alpha)8-barrel domain, it contains a domain, F, that is specific for branching and debranching enzymes. Pullulanase cDNA was expressed in Escherichia coli, and the purified protein was compared with the enzyme from spinach leaves. Identity of the two proteins was confirmed in terms of catalytic properties, N-terminal amino acid sequences and molecular masses. The pullulanase produced by E. coli showed the same microheterogeneity as the spinach leaf enzyme: it could be resolved into two substrate-induced forms by electrophoresis in amylopectin-containing polyacrylamide gels, and, in the absence of substrate, into several free forms (charge isomers) by isoelectric focusing or chromatofocusing. Rechromatofocusing of single free forms resulted in the originally observed pattern of molecular forms. However, heterogeneity of the protein disappeared on isoelectric focusing under completely denaturing conditions when only one protein band was observed. Post-translational modifications such as glycosylation and phosphorylation could be excluded as potential explanations for the protein heterogeneity. Therefore the microheterogeneity of spinach leaf pullulanase results from neither genetic variation nor post-translational modifications, but is a property of the single unmodified gene product. The different interconvertible forms of the pullulanase represent protein populations of different tertiary structure of the same polypeptide.

Leaf alkaloid contents of Tabernaemontana pachysiphon as influenced by endogenous and environmental factors in the natural habitat

Indole alkaloid contents were investigated in leaves of Tabernaemontana pachysiphon (Apocynaceae) trees in the natural habitat, Shimba Hills National Reserve, Kenya. The contents of the major alkaloids apparicine, tubotaiwine, tubotaiwine- N-oxide, and isovoacangine varied with site, leaf age, leaf growth form, position in the crown, and plant age. Alkaloid contents were highest in young leaves. Trees bearing aberrant small dwarf-leaves showed similar alkaloid patterns as young leaves from healthy trees. At single trees, the contents were found to increase from the top to the bottom of the crown. Tree age had little influence on leaf alkaloid contents. In even aged leaves of trees from different forest sites, alkaloid contents were highest at the site with highest soil cation exchange capacity (CEC) and base saturation.

Functional involvement of polypyrimidine tract-binding protein in translation initiation complexes with the internal ribosome entry site of foot-and-mouth disease virus

The synthesis of picornavirus polyproteins is initiated cap independently far downstream from the 5' end of the viral RNA at the internal ribosome entry site (IRES). The cellular polypyrimidine tract-binding protein (PTB) binds to the IRES of foot-and-mouth disease virus (FMDV). In this study, we demonstrate that PTB is a component of 48S and 80S ribosomal initiation complexes formed with FMDV IRES RNA. The incorporation of PTB into these initiation complexes is dependent on the entry of the IRES RNA, since PTB and IRES RNA can be enriched in parallel either in 48S or 80S ribosomal complexes by stage-specific inhibitors of translation initiation. The formation of the ribosomal initiation complexes with the IRES occurs slowly, is temperature dependent, and correlates with the incorporation of PTB into these complexes. In a first step, PTB binds to the IRES, and then the small ribosomal subunit encounters this PTB-IRES complex. Mutations in the major PTB-binding site interfere simultaneously with the formation of initiation complexes, translation efficiency, and PTB cross-linking. PTB stimulates translation directed by the FMDV IRES in a rabbit reticulocyte lysate depleted of internal PTB, and the efficiency of translation can be restored to the original level by the addition of PTB. These results indicate that PTB plays an important role in the formation of initiation complexes with FMDV IRES RNA and in stimulation of internal translation initiation with this picornavirus.

[The conservative and surgical therapy of traumatic humeral shaft fractures]

Sixty-three patients with humeral shaft fractures were evaluated clinically and radiographically 18 months after injury; 27 patients were treated surgically (group A) and 36 patients conservatively (group B). Analysis of the results according to a score by Kwasny revealed 6.2 points in group A and 2.2 points in group B (P < 0.0001; F = 46.9). The results of these two comparable groups suggest that conservative treatment of humeral shaft fractures is superior regarding mobility of the shoulder and elbow, strength, the incidence of neurological complications, pain, subjective rating and cosmesis. There were no differences on roentgenograms between the two groups (P = 0.48).

Photosynthesis and photoinhibition in a tropical alpine giant rosette plant, Lobelia rhynchopetalum

Carbodioxide uptake, oxygen evolution and chlorophyll fluorescence of leaves of Lobelia Lobelia rhynchopetalum Hemsl., a giant rosette plant of the tropical alpine regions of Ethiopia, were studied under field conditions at 4000 m above sea level. Our objective was to investigate the photosynthetic adaptation to the combination of wide fluctuation in diurnal temperature, high photon flux densities (PFD) and low CO₂ partial pressure encountered in these regions. At an ambient CO₂ partial pressure of c. 17 Pa, maximal rates of CO₂ uptake were low, ranging between 4 and 6 μmol m^-2 s^-1 . Such rates, however, required high PFDs and were observed only at levels of 1500 μmol photons m^-2 s^-2 . Carbon dioxide uptake was significantly inhibited when PFD was ≤ 2000 μmol photons m^-2 s^-1 . On the other hand, at saturating CO₂ levels, maximal photosynthetic oxygen evolution was higher (30 μmol C₂ m^-2 s^-1 ). saturating at the same PFD as CO₂ uptake. Quantum efficiency of CO₂ uptake (0.006 mol CO₂ mol photons^-1 , at high altitude and a low CO, partial pressure of 17 Pa) and even of oxygen evolution under CO₂ -saturating conditions in the leaf O₂ electrode (0.05 mol O₂ mo) photons^-1 ) indicated reduced photosynthetic efficiency. Electron transport rate (ETR) was strongly correlated with the leaf temperature. Non-photochemical quenching (NPQ) responded inversely to leaf temperature and stomatal conductance. The results indicated that in the morning, when the sun irradiates the partly frozen leaves with closed stomata, NPQ is the principal mechanism by which Lobelia leaves protect their photosynthetic apparatus. However, during the day, the predominant upright inclination of the leaves significantly contributes to protecting the leaves from excess light absorption. A comparison of the chlorophyll fluorescence of young and old leaves revealed that the former had high ETR and quantum efficiency of photosynthetic electron transport but a lower capacity for NPQ. Extremely high NPQ values but low ETR and low quantum efficiency were recorded for the old leaves. Thus, in the course of maturation the leaves apparently lose photosynthetic efficiency but increase their capability for protective non-photochemical quenching.

Randomised trial of roxithromycin in non-Q-wave coronary syndromes: ROXIS Pilot Study. ROXIS Study Group

BACKGROUND

There is serological evidence for an association between Chlamydia pneumoniae and coronary heart disease. We investigated the hypothesis that an antichlamydial macrolide antibiotic, roxithromycin, can prevent or reduce recurrent major ischaemic events in patients with unstable angina.

METHODS

The effect of roxithromycin was assessed in a double-blind, randomised, prospective, multicentre, parallel-group, placebo-controlled pilot study of 202 patients with unstable angina or non-Q-wave myocardial infarction. Patients were randomly assigned either roxithromycin 150 mg orally twice a day (n = 102) or placebo orally twice a day (n = 100). The treatment was for 30 days. Patients were followed up for 6 months. We report the primary clinical endpoints (cardiac ischaemic death, myocardial infarction, and severe recurrent ischaemia), assessed at day 31, in 202 patients on an intention-to-treat basis.

FINDINGS

A statistically significant reduction in the primary composite triple endpoint rates was observed in the roxithromycin group: p = 0.032. The rate of severe recurrent ischaemia, myocardial infarction, and ischaemic death was 5.4%, 2.2%, and 2.2% in the placebo group and 1.1%, 0%, and 0%, in the roxithromycin group, respectively. No major drug-related adverse effects were observed.

INTERPRETATION

Antichlamydial antibiotics may be useful in therapeutic intervention in addition to standard medication in patients with coronary-artery disease. Large-scale trials are needed to confirm these preliminary observations.

Sensitivity of transformed fibroblasts for intercellular induction of apoptosis is determined by their transformed phenotype

Intercellular induction of apoptosis defines a potential control mechanism of oncogenesis. It is based on induction of apoptosis in transformed fibroblasts by neighboring nontransformed fibroblasts. Transforming growth factor type beta (TGF-beta) represents the initial triggering molecule to induce nontransformed cells to release apoptosis-inducing factors. To test whether sensitivity for intercellular induction of apoptosis is directly dependent on the transformed phenotype, v-src-transformed rat fibroblasts and emerging revertants were tested for their sensitivity. All transformed cell clones were sensitive, whereas all revertant clones had lost their sensitivity in parallel with the loss of the transformed phenotype. In addition, revertants had regained the potential to induce apoptosis in transformed cells. Sensitivity to intercellular induction of apoptosis is therefore directly dependent on the transformed phenotype, whereas the ability to induce apoptosis is a specific feature of nontransformed fibroblasts.