Effects of endothelin-1 on epithelial ion transport in human airways

Endothelin-1 (ET-1) exerts many biological effects in airways, including bronchoconstriction, airway mucus secretion, cell proliferation, and inflammation. We investigated the effect of ET-1 on Na absorption and Cl secretion in human bronchial epithelial cells. Addition of 10(-7) M ET-1 had no effect on the inhibition of the short circuit current (Isc) induced by amiloride, a Na channel blocker. Addition of 10(-7) M ET-1 to the apical bath in the presence of amiloride increased Isc in cultured human bronchial epithelial cells studied in Ussing chambers. No effect was observed when ET-1 was added to basolateral bath, indicating that the involved ET-1 receptors are likely present only in the apical membrane of the cells. Use of Cl-free solutions and bumetanide reduced the ET-1-induced increases in Isc, indicating that ET-1 stimulates Cl secretion. The ET-1-induced increase in Isc was prevented by exposure to the ETB receptor antagonist BQ-788 but not to the ETA receptor antagonist BQ-123. ET-1 did not raise intracellular Ca levels, but increased the intracellular concentration of cAMP. These findings indicate that ET-1 is a Cl secretagogue in human airways and acts presumably through apically located ETB receptors and activation of the cAMP pathway.     

PDGF enhancement of IL-1 receptor levels in smooth muscle cells involves induction of an attachment-regulated,heparan sulfate binding site (IL-1RIII)

This study shows that increase in IL-1 receptor levels by platelet derived growth factor (PDGF) involves an enhancement of a matrix-dependent, low-affinity receptor that constitutes a heparan sulfate. Fibronectin attachment caused pronounced alterations in IL-1 receptor function in smooth muscle cells, involving a pronounced increase in cell surface binding from an average of 2,000 up to approximately 8,000 receptors/cell and an increase in affinity (K(a)) of the type I receptor from 1.8 +/- 0.9 x 10(9) to 3.7 +/- 0.5 x 10(9) M(-1). PDGF stimulation similarly enhanced the level of cell surface binding by between 30% and 100%, with, in general, less effect on cells plated on fibronectin. Further, PDGF had a pronounced effect on the type I receptor affinity in the absence of matrix attachment, increasing the K(a) from 1.77 +/- 0.93 x 10(9) to 5.1 +/- 2.1 x 10(9) M(-1). Scatchard analyses revealed that PDGF, similarly to fibronectin attachment, caused enhancement of a second low-affinity binding site. Antibody blocking showed that approximately 50% of the attachment-induced increase was independent of type I receptor binding. Further, a similar fraction of the cell surface interaction was blocked by soluble heparan sulfate and dependent on cell binding to the heparan binding site. Cross-linking demonstrated that, in addition to the type I receptor, IL-1 bound to a second high molecular weight complex of 300 kd, induced by fibronectin attachment as well as by PDGF in the absence of matrix. Biochemical analyses demonstrated that this second site constitutes a heparan sulfate, which directly interacted with the type I receptor after recruitment to the complex, and which bound up to 50% and 25% of the ligand after fibronectin attachment and PDGF stimulation, respectively. The data show that PDGF induces an attachment-regulated low-affinity IL-1 binding site in smooth muscle cells, constituting a heparan sulfate. Correlation of the recruitment of this component to the IL-1 receptor complex with structural regulation of receptor function and enhancement of IL-1-mediated responses suggests that this is a significant mechanism in PDGF augmentation of local inflammatory responses during vessel wall pathogenesis.     

Cellular life histories and bow tie biology.

Considering the life-long influences of fetal growth biology, it is of interest to further elucidate the nature of the fetal growth process itself. Previous analyses of longitudinal fetal ultrasound data led to the hypothesis that hypoxia signals were important aspects of normal growth biology and directed attention to the place of oxygen as a basic nutrient. From the perspective of the cell, both hypoxia and lack of energy substrate trigger a common adaptive pathway through their effects on ATP availability. Comparative data from animal studies and cell culture provide evidence for an integrated energy/oxygen signaling system that acts redundantly and hierarchically with cellular differentiation programs, providing opportunities for developmental flexibility in response to variable ecologic or environmental challenge. The multinodal and interactive design of the fetal growth process suggests that it follows what has been described as the "bow tie" model of metabolism, with implications for robust and inventive approaches to cell, organ, and whole organism construction.     

Evaluating the impact of a service fee on patient compliance

This paper addresses an evaluation of an administrative decision to change the manner in which services were paid for at a Student Health Center (SHC). The impact of the change in payment was observed through monitoring the number of scheduled appointments at the SHC which the patient failed to attend, reschedule, or cancel. The impact was assessed through a comparison of the weekly no-show rates from the year prior to the change in payment practices through the year following the change. A time-series statistical package was used to analyze the no-show data. Collateral measures on the number of students attending the university, staff opinions, and usage of the SHC by different student groups were collected. Evaluations of the impact of administrative decisions on health-related behavior were discussed, in addition to a discussion of the usefulness of time-series models for this type of evaluation.     

Expression of a NOS transgene in dystrophin-deficient muscle reduces muscle membrane damage without increasing the expression of membrane-associated cytoskeletal proteins

Muscular dystrophy that is caused by mutation of the membrane-associated, cytoskeletal protein called dystrophin, is accompanied by loss of a dystrophin-associated protein complex (DPC) that includes neuronal nitric oxide synthase (nNOS). Previous work showed that expression of a nNOS transgene in the dystrophin-deficient, mdx mouse greatly reduces muscle membrane damage. In this investigation, we test whether expression of a nNOS transgene in wild-type or mdx muscle increases expression of DPC proteins, or functionally related proteins in the integrin complex that are upregulated in dystrophin-deficiency, or affects expression of the dystrophin homolog, utrophin. Many members of the DPC are enriched in Western blots of cell membranes isolated from NOS transgenic muscle, compared to wild-type. Similarly, alpha7-integrin and the associated cytoskeletal proteins talin and vinculin are increased in NOS transgenic, non-dystrophic muscle. However, utrophin expression is unaffected by elevated NOS expression in healthy muscle. A similar trend in mRNA levels for these proteins was observed by expression profiling. Analysis of membrane preparations from mdx mice and NOS transgenic mdx mice shows that expression of the NOS transgene causes significant reductions in utrophin, talin, and vinculin. Expression profiling of mRNA from mdx and NOS transgenic mdx muscles also shows reduced expression of talin. Immunohistochemistry of mdx and NOS transgenic mdx muscle indicates that reduction in utrophin in NOS transgenic mdx muscle results from a decrease in regenerative fibers that express high levels of utrophin. Together, these findings indicate that the NOS transgene does not reduce dystrophinopathy by increasing the expression of compensatory, structural proteins.     

Evaluation of the harmonized alert sensing technology device for hemodynamic monitoring in chronic hemodialysis patients

The Harmonized Alert Sensing Technology (HASTE) device was developed to overcome the primary shortcomings of interval based noninvasive blood pressure (BP) monitoring. This study was conducted to assess the reliability of the HASTE system compared with standard cuff BP values in patients on hemodialysis. A total of 1,370 HASTE measurements were compared with oscillometric standard cuff systolic BP values in 42 sessions of 15 patients on hemodialysis. The average discrepancy between the HASTE and cuff systolic BP was 1.41 +/- 16.90 mm Hg. Compared with cuff measurements, 31% of systolic BP fell within a range of 5 mm Hg difference, 57% of systolic BP fell within 10 mm Hg, and 73% of systolic BP fell within a 15 mm Hg band. According to British Hypertension Society standards or Association for the Advancement of Medical Instrumentation criteria, the current HASTE method did not perform well. Technology to provide noninvasive hemodynamic monitoring is, however, in its developmental stage. The effort at continuous systolic pressure monitoring using existing, readily available, and frequently used techniques is exciting. Although the HASTE system as currently configured and calibrated did not adequately perform, variations in site analysis and conversion factors may increase pressure sensitivity and tracking over the course of a standard dialysis treatment.     

The Genetic Basis of Academic Achievement on the Queensland Core Skills Test and its Shared Genetic Variance with IQ

First, this study examined genetic and environmental sources of variation in performance on a standardised test of academic achievement, the Queensland Core Skills Test (QCST) (Queensland Studies Authority, 2003a). Second, it assessed the genetic correlation among the QCST score and Verbal and Performance IQ measures using the Multidimensional Aptitude Battery (MAB), [Jackson, D. N. (1984) Multidimensional Aptitude Battery manual. Port Huron, MI:Research Psychologist Press, Inc.]. Participants were 256 monozygotic twin pairs and 326 dizygotic twin pairs aged from 15 to 18 years (mean 17 years ± 0.4 [SD]) when achievement tested, and from 15 to 22 years (mean 16 years ± 0.4 [SD]) when IQ tested. Univariate analysis indicated a heritability for the QCST of 0.72. Adjustment to this estimate due to truncate selection (downward adjustment) and positive phenotypic assortative mating (upward adjustment) suggested a heritability of 0.76 The phenotypic (0.81) and genetic (0.91) correlations between the QCST and Verbal IQ (VIQ) were significantly stronger than the phenotypic (0.57) and genetic (0.64) correlations between the QCST and Performance IQ (PIQ). The findings suggest that individual variation in QCST performance is largely due to genetic factors and that common environmental effects may be substantially accounted for by phenotypic assortative mating. Covariance between academic achievement on the QCST and psychometric IQ (particularly VIQ) is to a large extent due to common genetic influences.     

Perceptual speed does not cause intelligence, and intelligence does not cause perceptual speed

There is ongoing debate whether the efficiency of local cognitive processes leads to global cognitive ability or whether global ability feeds the efficiency of basic processes. A prominent example is the well-replicated association between inspection time (IT), a measure of perceptual discrimination speed, and intelligence (IQ), where it is not known whether increased speed is a cause or consequence of high IQ. We investigated the direction of causation between IT and IQ in 2012 genetically related subjects from Australia and The Netherlands. Models in which the reliable variance of each observed variable was specified as a latent trait showed IT correlations of -0.44 and -0.33 with respective Performance and Verbal IQ; heritabilities were 57% (IT), 83% (PIQ) and 77% (VIQ). Directional causation models provided poor fits to the data, with covariation best explained by pleiotropic genes (influencing variation in both IT and IQ). This finding of a common genetic factor provides a better target for identifying genes involved in cognition than genes which are unique to specific traits.