Effect of choice of reference equation on analysis of pulmonary function in cystic fibrosis patients

Pulmonary function is an important measure of disease severity and prognosis in cystic fibrosis (CF). It is generally expressed as a percentage of a predicted value, calculated using regression equations derived from a reference population. A number of reference equations are in widespread use. The purposes of this study were to determine: 1) the extent to which, for a given absolute FEV(1) value, percent of predicted (PPFEV(1)) values vary when derived by different reference equations; and 2) whether these differences affect conclusions of longitudinal and cross-sectional analyses. Subjects were all Caucasians 6-18 years old in the 1990 Cystic Fibrosis Foundation Registry. We found clinically important discrepancies in PPFEV(1) when calculated by the methods of Dockery et al. [Am Rev Respir Dis 1983;128:405-412] and Wang et al. [Pediatr Pulmonol 1993;15:75-78] as compared to Knudson et al. [Am Rev Respir Dis 1983;127:725-734] or Polgar and Promadhat [Pulmonary Function Testing in Children 1971; Philadelphia: W.B. Saunders]. In longitudinal analyses, the choice of reference equation resulted in varying apparent rates of decline in FEV(1). For example, among subjects ages 12-14 years in 1990, the decline in PPFEV(1) from 1990-1995 varied between 2-11%, depending on the choice of reference equation. In cross-sectional analyses, the choice of reference equation affected the distribution of subjects classified as having mild, moderate, or severe lung disease. CF physicians should be aware of the impact of choice of reference equation in both clinical care and research.     

Quantitative evaluation of liver-specific promoters from retroviral vectors after in vivo transduction of hepatocytes

Hepatic gene therapy could be used to treat a number of inherited blood diseases such as hemophilia or thrombophilia. Although liver-directed retroviral transduction can result in long-term gene expression in vivo, the low level of protein production has limited its clinical application. We reasoned that the insertion of liver-specific promoters into retroviral vectors would increase gene expression in vivo. The 347- bp human alpha 1-antitrypsin (hAAT), the 810-bp murine albumin (mAIb), the 490-bp rat phosphoenolpyruvate carboxykinase (rPECK), and the 596- bp rat liver fatty acid binding protein promoters were inserted into a Moloney murine leukemia retroviral backbone containing the hAAT reporter gene. Vectors that produced appropriately sized RNA and hAAT protein in vitro were tested in vivo by transducing regenerating rat livers. Long-term serum expression of the hAAT reporter gene was normalized to retroviral transduction efficiency as determined by using a polymerase chain reaction-based assay of genomic DNA from transduced rat livers. The hAAT, mAIb, and rPEPCK promoters were, respectively, 35- , 8-, and 0.02-fold as strong as the previously studied constitutive Pol-II promoter. We conclude that the hAAT promoter resulted in the highest expression from a retroviral vector and may result in therapeutically significant expression of other clinically significant blood proteins.     

Molecular basis of altered red blood cell membrane properties in Southeast Asian ovalocytosis: role of the mutant band 3 protein in band 3 oligomerization and retention by the membrane skeleton

Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation.     

Effects of interleukin-11 on the proliferation and cell cycle status of myeloid leukemic cells

Interleukin-11 (IL-11) is a pleiotropic cytokine with effects on many different targets. Within the hematopoietic system, the effects of IL- 11 are largely manifest only through combination with other cytokines, including IL-3 and Steel factor (SF). In the present study, we addressed the question of IL-11 responsiveness within the different types of human leukemic cells, as well as the mechanism of action of IL- 11 at the cellular level. Analysis of a panel of samples from different patients with acute myeloblastic leukemia (AML) and myeloid leukemic cell lines indicated that IL-11 alone was ineffective in supporting myeloid leukemic cell growth but frequently enhanced growth supported by IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), or SF. In contrast, three acute pre-B lymphocytic leukemia (pre-B-ALL) and two acute T lymphocytic leukemia (T-ALL) lines failed to respond to IL- 11 alone or when combined with other cytokines. The growth enhancement of IL-11 among the AML patient samples was dose dependent and remarkably constant with half-efficient concentrations in the range of 0.3 to 0.4 ng/mL. The thymidine suicide studies with the patient samples revealed that 40% to 50% of the blast cells were in S-phase when exposed for 16 hours to IL-3 and this level was increased to 70% to 90% in response to either IL-11 or IL-6. Our data suggest that the latter two interleukins act synergistically with the direct mitogenic factor, IL-3, in triggering AML blast-cell proliferation. Detailed analysis with several patient samples further revealed that SF and IL- 11 both enhance IL-3-supported clonogenic growth of AML blasts and the combination of all three growth factors yields optimal growth. In contrast, IL-6 does not further enhance the effect of IL-11. These results indicate that SF and IL-11 enhance IL-3-dependent clonogenic growth through two distinct pathways, whereas IL-6 and IL-11 may trigger the same pathway.     

Diagnostic accuracy of oropharyngeal cultures in infants and young children with cystic fibrosis.

The objective of this study was to assess the diagnostic accuracy of oropharyngeal (OP) cultures relative to simultaneous bronchoalveolar lavage (BAL) cultures in very young children with CF, and to examine the effects of bacterial density, age, and study cohort on diagnostic accuracy. Respiratory culture data were analyzed from three independent, prospective studies involving simultaneous collection of 286 OP and BAL cultures from 141 children with CF <5 years of age. For predicting any growth of Pseudomonas aeruginosa (Pa) from the lower airway in subjects /=10(3) or >/=10(5) cfu/mL. Specificity for Pa declined significantly with increasing age. In children with CF <5 years of age, the specificity and negative predictive value of OP cultures for Pa are high, while the sensitivity and positive predictive value are poor. Thus, in this age range, a negative throat culture is helpful in "ruling out" lower airway infection with Pa. However, a positive culture does not reliably "rule in" the presence of Pa in the lower respiratory tract. These findings may have implications for study design and interpretation as well as clinical management of young children with CF.     

Vascular findings in CTA body and extremity of critically ill COVID-19 patients: commonly encountered vascular complications with review of literature

Emergency Radiology - The purpose of our review is to discuss the role of CT angiography (CTA) in evaluating a variety of vascular complications in critically ill COVID-19 patients. The COVID-19...     

Intestinal helminth infestation is associated with increased bronchial responsiveness in children

Non-atopic asthma is the predominant phenotype in non-affluent parts of Latin America. We recently reported that infestation with Ascaris lumbricoides increased the risk of non-atopic asthma in less affluent areas of Brazil but the mechanism is unclear. The present study was conducted to determine whether helminth infestation is associated with heightened bronchial responsiveness (BHR), a common finding in asthma. A random sample of 50 asthmatic and 50 non-asthmatic controls (mean age 10.1 years) were selected from a larger cohort (n = 1,011) without knowledge of their helminth infestation status. Three stool samples were collected from each child on different days and each sample was analyzed by the Kato-Katz method for quantitative determination of helminth eggs. Bronchial provocation tests were performed with inhaled 4.5% hypertonic saline using the ISAAC Phase II standardized protocol. There was no difference between the prevalence of positive BHR in the asthmatics (20.4%) compared with the controls (14.6%) (P = 1.0). Helminth infestation was detected in 24.0% of children, with A. lumbricoides being the most common. Children with high load infestation (>or=100 eggs/g) were five times more likely to have BHR than children with low load or no infestation. Despite the small sample size the results of the present study suggest that the link between high load helminth infestation and non-atopic asthma may be mediated via heightened bronchial responsiveness, possibly due to an inflammatory response to the pulmonary phase of the helminth life cycle.     

The effect of thyroid dysfunction and fasting on placenta inner ring deiodinase activity in the rat

The placenta contains iodothyronine 5-deiodinase activity (P5-Dase) that probably acts on iodothyronines in the fetal circulation to convert T4 to rT3 and T3 to 3,3'-T2. Since thyroid status and fasting have profound effects on iodothyronine deiodinases in other tissues, the present studies were performed to determine if these perturbations affected P5-Dase. Control and treated rats were mated and killed near term on the 20th day of gestation. P5-Dase was determined in placenta homogenates enriched with dithiothreitol by measuring the conversion of T4 to rT3. In four of five studies, P5-Dase was similar in dams that underwent thyroidectomy (Tx) on day 7 of gestation and sham Tx dams. P5-Dase was not altered in dams that were treated with methimazole (MMI) to induce maternal and fetal hypothyroidism. Treatment of dams with supraphysiological doses of T4, beginning on the seventh day of gestation, did not significantly affect P5-Dase. In three of four studies, P5-Dase was similar in fed dams to values in dams fasted for the last 5 days of pregnancy. Placenta iodothyronine 5'-deiodinase activity (P5'-Dase) was also measured in some studies. P5'-Dase was not decreased in Tx rats and was modestly decreased in MMI-treated rats. However, the effect of MMI was not reversed by the administration of supraphysiological doses of T4, Tx, MMI treatment, and fasting all decreased hepatic T4 5'-deiodinase activity in pregnant rats. These results strongly suggest that thyroid status and fasting do not alter P5-Dase activity.     

Adult stem cells: Early clinical trials and perspective

Cardiac repair with cell-based therapy is a promising treatment for patients with coronary heart disease. Preclinical and early clinical studies have shown that stem cell therapy is safe and effective in improving left ventricular function and myocardial perfusion. Specifically, cardiac stem cell therapy may be beneficial in reducing left ventricular remodeling in patients with myocardial infarction and in improving symptoms and preventing cardiac enlargement in patients with chronic ischemic heart disease. Although not well defined, multiple mechanisms, including paracrine effects, probably contribute to stem cell-mediated cardiac repair. The issues of timing, mode of delivery, and cell dose need to be systematically studied to maximize benefits. Nevertheless, rapid advancements may soon make cardiac stem cell therapy a central part of the treatment regimen for patients with coronary heart disease.     

Changes in house design reduce exposure to malaria mosquitoes

House design may affect an individual's exposure to malaria parasites, and hence to disease. We conducted a randomized-controlled study using experimental huts in rural Gambia, to determine whether installing a ceiling or closing the eaves could protect people from malaria mosquitoes. Five treatments were tested against a control hut: plywood ceiling; synthetic-netting ceiling; insecticide-treated synthetic-netting ceiling (deltamethrin 12.5 mg/m2); plastic insect-screen ceiling; or the eaves closed with mud. The acceptability of such interventions was investigated by discussions with local communities. House entry by Anopheles gambiae, the principal African malaria vector, was reduced by the presence of a ceiling: plywood (59% reduction), synthetic-netting (79%), insecticide-treated synthetic-netting (78%), plastic insect-screen (80%, P < 0.001 in all cases) and closed eaves (37%, ns). Similar reductions were also seen with Mansonia spp., vectors of lymphatic filariasis and numerous arboviruses. Netting and insect-screen ceilings probably work as decoy traps attracting mosquitoes into the roof space, but not the room. Ceilings are likely to be well accepted and may be of greatest benefit in areas of low to moderate transmission and when used in combination with other malaria control strategies.