[Cohort of patients initiated to home ventilation. Observational and prospective study]. / Cohorte de patients nouvellement traités par ventilation non invasive à domicile. Étude observationnelle, prospective et multicentrique.

Cohort of patients initiated to home ventilation. Observational and prospective study. The effectiveness of home noninvasive ventilation (NIV) for chronic respiratory failure (CRF) is well established. However, few data are available about home NIV prescription and utilization according to the different etiologies of respiratory failure. The ANTADIR Federation, in partnership with the Ventilatory Support Group of the French Speaking Pulmonary Society, has set up a national, observational and multicenter cohort study. The main goal of this study is to analyze the clinical data justifying home NIV prescription in patients with chronic respiratory insufficiency. The secondary objectives will be to assess: the evolution of comorbidities or their occurrence, hospitalizations, NIV compliance, dropout and survival. The population includes patients with chronic respiratory failure newly initiated onto NIV, both in a stable state and following an acute exacerbation who qualify for long-term NIV. Data collected include: diagnosis and comorbidities, age, sex, BMI, biomarkers (hematocrit, arterial blood gases, total CO2) and functional data (FEV1, VC, TLC), nocturnal results (SaO2, PtcCO2), type of ventilator used, ventilator parameters and mask type. Follow-up data will be collected at 4 months, 1 year and 2 years and will include: hospitalizations, changes in prescription, adherence, dropouts and deaths. This work will make it possible to obtain new scientific information on long-term NIV use in France.

[Oxygen therapy by a portable concentrator with a demand valve: a randomised controlled study of its effectiveness in patients with COPD]. / L'oxygénothérapie par concentrateur portable à valve à la demande : étude randomisée et contrôlée de son efficacité clinique chez des patients BPCO.

INTRODUCTION: There is doubt concerning the clinical effectiveness of portable oxygen concentrators with a control valve (PCDV) and their appreciation by patients. Objectives. To compare the effectiveness and appreciation of oxygen therapy by PCDV and liquid oxygen by continuous f low (O(2)Liq). METHODS: Nineteen patients with COPD were randomised to receive PCDV or O(2)Liq at rest and during a 6 minute walk test (6MWT). For each mechanism they assessed, by visual analogue scales, the convenience and portability, the noise, and the discomfort of the nasal oxygen delivery. RESULTS: The 6MW distance was 315 ± 120 m with PCDV and 325 ± 114 m with O(2)Liq (P>0.05). Dyspnoea and the desaturation induced by the 6MWT were identical with both systems (P>0.05). The time spent with a SaO(2)<90 % was 289 ± 69 s with PCDV and 242 ± 130 s with O(2)Liq (P=0.08). PCDV was noisier than O(2)Liq (P<0.05); there was no difference in convenience and portability or in nasal discomfort. CONCLUSION: The PCDV model that we tested was equally effective to O(2)Liq. However, the prescription of this type of system is a matter of personal choice.

Home treatment for chronic respiratory failure in children: a prospective study.

Home treatment for children with chronic respiratory failure (CRF) is increasing. However, the causes of CRF in children and the details of their home treatment are not well-known. The aim of this study was to describe the causes of CRF in the paediatric population and the treatments that the patients received at home. We surveyed all children (aged < or = 18 yrs) entering the Association Nationale pour le Traitement à Domicile de l'Insuffisance Respiratoire chronique (ANTADIR) for home treatment of CRF between March 1992 and March 1993. Two hundred and eighty seven children (178 boys, 62%) started home treatment for CRF during the year. One hundred and eleven patients had obstructive respiratory disease: cystic fibrosis (CF) (n = 24); bronchopulmonary dysplasia (BPD) (n = 79); other obstructive respiratory disease (n = 8). One hundred and seventy six patients had restrictive lung disease: neuromuscular disease (n = 87); kyphoscoliosis (n = 21); pulmonary fibrosis (n = 6); cardiac disease (n = 14); stomatological disease (n = 10); other restrictive respiratory disease (n = 9); and 29 miscellaneous causes. One hundred and thirteen patients received oxygen therapy, with a mean daily use of 17.7 h (20 h.day-1 for BPD patients and 12.3 h.day-1 for CF patients). Oxygen was delivered by a concentrator in 88% of cases. One hundred and fifty eight children received mechanical ventilation (MV). Five children received nasal continuous positive airway pressure ventilation for sleep apnoea, four had pneumatic belt ventilation, and 12 had a tracheostomy without MV. Treatment was stopped in 21 children, because of death in nine and improvement in the other 12. Home treatment for children with CRF is well developed in France via the ANTADIR network. Causes of CRF in children are heterogeneous, with a relatively good prognosis.

Molecular forms of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase expressed in rat skeletal muscle.

The rat cDNA for the muscle-type (M) isozyme of 6-phosphofructo-2-kinase (PFK-2)/fructose-2,6-bisphosphatase (FBPase-2) contains two putative translation initiation sites. To determine whether the M isozyme expressed in rat skeletal muscle corresponds to the short (PFK2M-sf) or the long (PFK2M-lf) isoform, we have expressed them in Escherichia coli. A third construction was also expressed in which the second ATG codon was deleted (PFK2M-lf delta ATG) to ensure that initiation started at the first ATG. The properties of these recombinant proteins were compared with those of the PFK-2/FBPase-2 present in rat skeletal muscle and liver. The recombinant proteins displayed PFK-2 and FBPase-2 activities and the M(r) values of the subunits measured by SDS-polyacrylamide gel electrophoresis were compatible with the calculated ones. The purified recombinant lf form contained not only the expected lf band (54,500 M(r)) but also the sf band (52,000 M(r)), indicating that the expression system could synthesize the long and the short isoforms from the same mRNA. The kinetic properties of the recombinant sf form were not different from those of the rat muscle enzyme. By contrast, lf delta ATG PFK-2 displayed a higher Km for its substrates and a lower Vmax. Immunoblotting with an antibody directed against the long isoform revealed a 54,500 M(r) band both in the lf and the lf delta ATG recombinant, but no band in rat skeletal muscle extracts. In these extracts, one band of 52,000 and a minor one of 54,500 M(r) were detected by an anti PFK-2/FBPase-2 antibody. The 54,500 M(r) band was recognized by an antibody directed against the L isozyme, suggesting that a small amount of the latter is expressed in skeletal muscle. Thus, the M isozyme differs from the L isozyme by replacement of the first 32 amino acids of the L isozyme by an unrelated nonapeptide.

Rat hepatoma (HTC) cell 6-phosphofructo-2-kinase differs from that in liver and can be separated from fructose-2,6-bisphosphatase.

6-Phosphofructo-2-kinase was purified from rat liver and hepatoma (HTC) cells. The HTC cell enzyme had kinetic properties different from those of the liver enzyme (more sensitive to inhibition by citrate and not inhibited by sn-glycerol 3-phosphate) and was not a substrate of the cyclic-AMP-dependent protein kinase. Unlike the liver enzyme, which is bifunctional and phosphorylated by fructose 2,6-[2-32P]bisphosphate, the HTC cell enzyme contained no detectable fructose-2,6-bisphosphatase activity and phosphorylation by fructose 2,6-[2-32P]-bisphosphate could not be detected. HTC cell fructose-2,6-bisphosphatase could be separated from 6-phosphofructo-2-kinase activity by purification. Antibodies raised against liver 6-phosphofructo-2-kinase did not precipitate HTC cell fructose-2,6-bisphosphatase whose kinetic properties were completely different from those of the liver enzyme.

Immunochemical and structural similarities in toxin A and toxin B of Clostridium difficile shown by binding to monoclonal antibodies.

Clostridium difficile toxins A and B were shown to share immunochemical and structural features, including shared sequential epitopes. Nineteen hybridomas generated after immunization of mice with a mixture of toxoids produced monoclonal antibodies, all IgM(x), which bound to toxin A and toxin B in a solid-phase radioimmunoassay (RIA). None of the antibodies neutralized the cytotoxicity of either toxin, alone or in pairs, nor did they neutralize mouse lethality. The antibodies did not inhibit hemagglutination by toxin A, and none of those tested neutralized the toxin's enterotoxic activity. Studies of binding of antibodies to native toxins in the RIA showed that the antibodies differed in their recognition of the toxins. Many of the antibodies bound with higher avidity to toxin A than to toxin B. In Western blots, all the antibodies recognized both toxins in the native state; in addition, some antibodies recognized the minor cytotoxic species of toxin B. When the toxins were denatured and reduced, five antibodies bound to both toxins, five to A only, and nine to neither, demonstrating that the antibodies had different epitope specificities. Further structural comparisons were made by investigation of mol. wts, subunit structures and amino acid compositions. The native mol. wts of toxin A and toxin B, as determined by electrophoresis to equilibrium in 4-30% polyacrylamide gel electrophoresis (PAGE), were 430,000 and 368,000, respectively. Denatured and reduced toxins each had a single subunit of 315,000. Both toxins had about 50% hydrophobic amino acids.

Comparison of purified bovine heart and rat liver 6-phosphofructo-2-kinase. Evidence for distinct isoenzymes.

Rat liver and bovine heart 6-phosphofructo-2-kinase were purified by the same procedure. Compared with the liver enzyme, the heart enzyme had a smaller apparent Mr, different kinetic properties, was not inactivated by cyclic AMP-dependent protein kinase, and contained less fructose-2,6-bisphosphatase activity. These differences suggest that heart and liver 6-phosphofructo-2-kinase are distinct isoenzymes. Likewise, 6-phosphofructo-2-kinase from rat heart and skeletal muscle was not inactivated on treatment with cyclic AMP-dependent protein kinase.

Effects of dicyclohexane derivatives on androgen metabolism in the rat prostate.

Dicyclohexane derivatives, which inhibit the binding of testosterone and dihydrotestosterone (DHT) to the androgen-binding protein (ABP) of rat epididymis without interfering with their binding to the androgen receptor, show a similar selectivity in their effects on androgen metabolism. Their ability to inhibit the aromatization of testosterone has been reported previously. This paper demonstrates that they are potent inhibitors of 3 alpha(beta)-hydroxysteroid:NAD(P)+ oxidoreductase activity (3-HSD) in the particulate fraction from rat prostate gland; the values of Ki for their inhibition of this enzyme are similar to that of the Km for DHT as substrate. The dicyclohexane derivatives are markedly less effective against the cytosolic NADPH-dependent 3-HSD, and they do not appear to inhibit testosterone 5 alpha-reductase activity. These characteristics are likely to complicate the proposed use of the dicyclohexane derivatives as probes for the role of ABP in vivo. However, they may be of interest in the study of structure-activity relationships in androgen-metabolizing enzymes, particularly in the examination of the different forms of 3-HSD.

Differential cytotoxic effects of toxins A and B isolated from Clostridium difficile.

Toxin A and toxin B preparations of Clostridium difficile have been shown to affect metabolic functions of intact HeLa cells with different kinetics. The cytotoxins were purified from dialyzed filtrates of C. difficile strain VPI 10463 by hydrophobic interaction chromatography and ion-exchange chromatography and were concentrated by dialysis or by ultrafiltration. The toxins, which are immunologically unrelated, were analyzed by polyacrylamide gel electrophoresis and by immunochemistry with the Western blot technique. Toxin A was resolved into one major cytotoxic protein and a minor, rapidly migrating species that did not comigrate with toxin B. Toxin B was resolved into one major and three minor cytotoxic proteins. One protein comigrating with toxin A had no cytotoxic activity. The highly purified toxin A at 1.0 mg/ml caused loss of intracellular K+ and inhibition of protein synthesis in HeLa cells within 1 h. These effects correlated with morphological changes indicating cytotoxicity. At lower protein concentrations of toxin A (10- to 100-fold less), however, cytotoxic effects were seen at 120 min, whereas no changes in K+ levels or protein synthesis were yet evident. The toxin B preparation, 1,000-fold more toxic than toxin A, was diluted to equivalent cytotoxicity as measured in the overnight assay. Toxin B caused loss of K+ and inhibition of protein synthesis well after cytotoxic morphological changes were complete. In contrast, at higher protein concentrations (2- to 2,000-fold more), intracellular K+ was lost completely by 120 min. The effects on cell rounding and protein synthesis were incomplete at 120 min, but increased with the toxin B concentration.