Big endothelin-1 and endothelin-1 plasma levels are correlated with the severity of primary pulmonary hypertension

STUDY OBJECTIVES

Primary pulmonary hypertension (PPH) is a rare disease of unknown etiology that is characterized by a poor prognosis. This study was undertaken to investigate possible correlations between endothelin (ET)-1 and big ET-1 plasma levels and the severity of PPH.

PATIENTS

Sixteen consecutive patients with PPH were included.

INTERVENTIONS

Hemodynamics of patients with PPH were measured by right-heart catheterization, and a 6-min walk test was performed.

MEASUREMENTS

Plasma levels of the biologically active peptide ET-1 and its precursor big ET-1 were determined in blood samples from the pulmonary artery, peripheral artery, and peripheral vein by radioimmunoassay.

RESULTS

A strong correlation was shown between pulmonary vascular resistance, mean pulmonary artery pressure, cardiac output, cardiac index, 6-min walk data, and elevated plasma levels of big ET-1 as well as mature ET-1 plasma levels at all sites of blood sampling (p < 0.01 and p < 0.05, respectively).

CONCLUSIONS

Levels of circulating ET-1 might become a prognostic marker for patients with PPH and serve as a tool for the selection of patients who may benefit from treatment with ET-receptor antagonists.

Infection control programs at children's hospitals: a description of structures and processes

BACKGROUND

Infection control (IC) structures and processes determine the effectiveness of surveillance efforts to prevent infections in health care settings.

METHODS

A survey was sent to 56 children's hospitals collaborating in the Pediatric Prevention Network (PPN).

RESULTS

Completed surveys were returned from 48 hospitals. Responsibility for the IC program resided with the medical director (21%); vice president for patient care (18%); quality improvement director (17%); other senior hospital administrator (15%); or other hospital personnel (18%). Forty-two hospitals had an IC committee; 32 had antimicrobial restriction/control policies; and 21 had an antimicrobial restriction/control task force or committee. Components of antimicrobial restriction programs included infectious disease specialist approval, restricted formularies, selective susceptibility test reporting, and staff education programs. Many methods were used to detect infections, including microbiology laboratory reports (100%); record reviews (98%); informal reports from providers (90%); and readmission reviews (77%).

CONCLUSIONS

Children's hospitals vary widely in how they design and implement their IC functions. These variations influence adverse event detection and nosocomial infection rate calculations. If medical errors, including nosocomial infections, are to be detected and hospital rates compared, standardized methods to collect, analyze, and report data are needed. The PPN has initiated activities to standardize surveillance and IC practices in participating hospitals.

Pediatric Prevention Network: a multicenter collaboration to improve health care outcomes

Nosocomial infections and antimicrobial resistance are major causes of mortality and morbidity and have become a major public health focus. To date, most national and international nosocomial infection surveillance and prevention activities have been focused on adults, despite the fact that pediatric patients are at high risk for nosocomial infections because of their immature immune systems and prevalent device usage. In 1997 the Hospital Infections Program at the Centers for Disease Control and Prevention and the National Association of Children's Hospitals and Related Institutions partnered to establish a Pediatric Prevention Network. Infection control professionals and their hospital administrators at all children's hospitals were invited to participate. The objectives of the network are to establish baseline infection rates; design, implement, and evaluate prevention interventions; establish benchmark rates and best practices; and serve as a site for multicenter studies to improve outcomes for hospitalized children. This network serves as a model for quality improvement systems in health care.

[Severe precapillary pulmonary hypertension in possible antiphospholipid syndrome--partially successful long-term therapy with continuous intravenous iloprost administration. A case report with discussion of new treatment methods]

Undifferentiated connective tissue disease with secondary antiphospholipid syndrome was diagnosed in a 33 year old woman after recurrent arterial thromboses, two miscarriages and myocarditis. Despite effective immunosuppression and anticoagulation her initially mild precapillary pulmonary hypertension progressed in the absence of thromboembolic events, cardiopulmonary disease or other systemic disorders. With continuous i.v. iloprost in a dosage of up to 4.5 ng/kg/min for a total of 15 months, her 6 min walking-distance improved from 210 to 315 m, the pulmonary vascular resistance decreased from 1710 to 1111 dyn x s x cm-5 and the mean pulmonary arterial pressure decreased from 64 to 54 mmHg. This partial success of conservative treatment enabled a reassessment of the necessity for heart and lung transplantation.

Group A streptococci efficiently invade human respiratory epithelial cells

Although infection by group A streptococci is a model of extracellular mucosal pathogenesis, these organisms can be associated with highly invasive infections resulting in sepsis and shock. Over the last 6 yr this species has renewed its reputation as a significant cause of sepsis and has piqued interest in the mechanism by which some strains are better able to breach mucosal barriers to gain access to the bloodstream than are others. An internalization assay was developed on the basis of resistance of intracellular streptococci to penicillin and gentamicin. Experiments showed that stationary-phase, as opposed to logarithmic-phase, bacteria are efficiently internalized and can persist in cultured human cells. Electron microscopy confirmed that streptococci were contained within intracellular vacuoles. Various strains of streptococci revealed significant differences in their capacity to be internalized. Two type M1 streptococci isolated from blood infections were internalized at frequencies equal to those reported for Salmonella and Listeria monocytogenes and greater than the frequency of a clonal variant from a case of pharyngitis.

Intracellular distribution of endothelin-1 receptors in rat liver cells

We studied the binding of (125I)-endothelin-1 as well as that of the vasopressin analogue (125I)-[8-phenylpropionyl]-LVP to purified plasma membranes, Golgi cisternae and cell nuclei from rat liver. Cell organelles were isolated by differential centrifugation and discontinuous sucrose gradients. Endothelin-1 exhibited specific binding to plasma membranes, Golgi cisternae and nuclei, while the binding of (125I)-[8-phenylpropionyl]-LVP was restricted to the plasma membranes. The number of receptors (Bmax) and the binding constants (Kd) were determined by Scatchard analysis of competition binding studies. In all cases only one class of Et-1 binding sites could be detected. The presence of Et-1 receptors on the Golgi complex either indicates that the receptor is glycosylated within the cisternae or alternatively, there exists a recycling pathway. The unexpected finding of Et-1 receptors on highly purified nuclei suggests that this peptide may exert part of its biological functions intracellularly via the nucleus.

Transposition of a plasmid deoxyribonucleic acid sequence that mediates ampicillin resistance: identity of laboratory-constructed plasmids and clinical isolates

The structural gene for ampicillin resistance resides upon a 3.2 X 10(6)-dalton sequence of deoxyribonucleic acid, TnA that can be transposed from replicon to replicon in laboratory experiments. TnA was transposed from a large conjugative plasmid to a small nonconjugative plasmid, RSF1010. Several RSF1010::TnA plasmids isolated in these laboratory experiments have been shown to be identical to plasmids found in clinical isolates. These data provide direct support to the theory that transposition of drug resistance genes play a key role in the evolution of R plasmids.

Transposition of a plasmid deoxyribonucleic acid sequence that mediates ampicillin resistance: independence from host rec functions and orientation of insertion

Insertion of the transposable deoxyribonucleic acid sequence that specifies the TEM beta-lactamase (TnA) occurred in at least 19 sites on the 5.5 x 10(6)-dalton plasmid RSF1010. There was no significant difference in the frequency of transposition or in the distribution of TnA insertion sites for recombinant plasmids isolated from recombination-proficient (rec+) or recombination-deficient (rec-) bacterial host cells. The site and orientation of TnA insertions were determined by both heteroduplex analysis and enzymatic digestion with restriction endonucleases. Insertion in the gene encoding for sulfonamide resistance occurred without circular permutation in one or the other of two distinct orientations. Insertions in orientation P were strongly polar on distal gene expression, whereas insertions in orientation M were mutagenic but not polar. In addition, we have observed that TnA elements from different R plasmids show fine structural heterogeneity, and that TnA insertion at a site adjacent to the origin of replication causes an increase in plasmid copy number.

Translocation of a plasmid DNA sequence which mediates ampicillin resistance: molecular nature and specificity of insertion

A series of recombinant plasmids was generated in Escherichia coli in which the TEM beta-lactamase translocon (TnA) was inserted into the small plasmid RSF1010. RSF1010 is a 5.5 X 10(6) dalton nonconjugative plasmid which confers resistance to streptomycin and sulfonamide. The recombinant plasmids can be classified into three clearly defined phenotypic groups. Group I is ampicillin-, streptomycin- and sulfonamide-resistant. Group II is ampicillin- and sulfonamide-resistant but has lost streptomycin resistance. Group III is ampicillin-resistant but is sensitive to sulfonamide and shows a simultaneous 30-fold reduction in the minimal inhibitory concentration of streptomycin. It was possible to map the site of insertion of TnA within RSF1010 by electron microscope studies of DNA heteroduplexes formed between RSF1010 and recombinant plasmids. Insertions of TnA occur at, at least, 12 distinct sites in a region corresponding to one-third of the RSF1010 DNA molecule. Those insertions giving rise to particular phenotypes are clustered. Insertions of TnA-like insertion sequences (IS) appear to give rise to strongly polar mutations.