Iridium(III)-catalyzed β-trifluoromethyl enone carbonyl-directed regioselective ortho-C(sp2)-H olefination

Due to the lower LUMO energy level at the β-position of α,β-unsaturated-β-trifluoromethyl enone than that of its non-fluorinated counterpart, there is a challenge to activate the sp2 C-H bond of aromatic rings. Herein, we have reported iridium(III)-catalyzed β-trifluoromethyl enone carbonyl-directed regioselective aromatic C(sp2)-H olefination with acrylates under oxidative conditions. Furthermore, coupling with natural product-derived acrylates, scale-up and product diversification have also been performed.

Pyridine C(sp2)-H bond functionalization under transition-metal and rare earth metal catalysis

Pyridine is a crucial heterocyclic scaffold that is widely found in organic chemistry, medicines, natural products, and functional materials. In spite of the discovery of several methods for the synthesis of functionalized pyridines or their integration into an organic molecule, new methodologies for the direct functionalization of pyridine scaffolds have been developed during the past two decades. In addition, transition-metal-catalyzed C-H functionalization and rare earth metal-catalyzed reactions have flourished over the past two decades in the development of functionalized organic molecules of concern. In this review, we discuss recent achievements in the transition-metal and rare earth metal-catalyzed C-H bond functionalization of pyridine and look into the mechanisms involved.

Catalytic and Chemodivergent Synthesis of 1-Substituted 9H-Pyrrolo[1,2-a]indoles via Annulation of β-CF3 Enones with 3-Substituted Indoles

Chemodivergent reactions are more advantageous in organic synthesis that yield diversely functionalized scaffolds from common starting materials. Herein, we report an efficient metal-free chemodivergent protocol for the synthesis of 1-substituted 9H-pyrrolo[1,2-a]indole derivatives in the presence of catalytic amounts of Lewis acid/Brønsted acid conditions using 3-substituted indoles and β-trifluoromethyl-α,β-unsaturated ketones. Fine-tuning of the catalyst and solvent system in the reaction conditions deliver the trifluoromethyl, trifluoroethylcarboxylate, or carboxylic acid substituents on the C1-position of 9H-pyrrolo[1,2-a]indole derivatives in situ. It is postulated that the solvent and LA/BA catalyst interaction was found to be crucial for the catalytic C-F activation in these transformations.

To determine the survival, prevalence and associated factors of exclusive breastfeeding practices in South India

Context

Exclusive breastfeeding (EBF) provides protection to the child from risk of obesity, overweight, type II diabetes and helps in enhancing brain development, learning capabilities and also reduces gastrointestinal infections. Breast problems, societal barriers, insufficient support, poor knowledge, mode of delivery and community beliefs are associated.

Aim

To determine the survival and prevalence of exclusive breast-feeding practice and their associated factors.

Settings and Design

An ambispective community-based observational study was conducted.

Materials and Methods

A sample of 441 mothers was estimated with a prevalence of EBF of 54.9% based on the National Family Health Survey 2015-16.

Study Procedure

The selected mothers with an infant less than one year of age and those with infants less than six months were interviewed retrospectively and prospectively and information on the duration of EBF, demography and factors associated were collected.

Statistical Analysis Used

The data were analysed using IBM SPSS, version 22. The Chi-square test and binary logistic regression were used to determine the associated factors for EBF. A P value of <0.05 was considered significant.

Results

EBF survival rate was good till three months and decreased drastically after five months. EBF practice in the present study was 69.4%. Birth order, maternal age, birth weight, paternal education and religion were significantly associated with EBF.

Conclusion

Primary health care providers in the community should also consider the cultural factors and educate the mothers on the practice of EBF to reduce morbidity and mortality and promote better health for a healthy, strong, younger population.

Maternal and Child Health Pipeline Training Programs: A Description of Training Across 6 Funded Programs

Purpose

The HRSA-funded maternal and child health pipeline training programs (MCHPTPs) are a response to the critical need to diversify the MCH workforce, as a strategy to reduce health disparities in MCH populations. These MCHPTPs support students from undergraduate to graduate education and ultimately into the MCH workforce.

Description

The models and components of training across the six MCHPTPs funded in 2016–2021 are summarized, to examine the design and delivery of undergraduate pipeline training and the insights gained across programs.

Assessment

Strategies that emerged across training programs were organized into three themes: recruitment, support for student persistence (in education), and pipeline-to-workforce intentionality. Support for student persistence included financial support, mentoring, creating opportunity for students to develop a sense of belonging, and the use of research as a tool to promote learning and competitiveness for graduate education. Finally, the link to Maternal and Child Health Bureau (MCHB) long-term training and other MCHB opportunities for professional development contributed significant nuance to the pipeline-to-workforce objectives of these programs.

Conclusions

The MCHPTPs not only increase the diversity of the MCH workforce, they also actively prepare the next generation of MCH leaders. The intentional connection of undergraduates to the infrastructure and continuum of MCH training, underscores the comprehensive impact of this funding.

Unconditional probability of dying and age-specific mortality rate because of major non-communicable diseases in India: Time trends from 2001 to 2013

Background:

Unconditional probability of dying because of four major non-communicable diseases (NCDs) between 30 and 70 years of age is the selected global indicator to measure the impact of NCD prevention and control programs.

Objective:

To calculate the unconditional probability of dying and age-specific mortality rate because of major NCDs in India from 2001 to 2013.

Methods:

This study used multiple data sources that are available in the public domain—Census 2001 and 2011, Sample Registration System, causes of death reports in 2001–03, 2004–06, and 2010–13. Unconditional probability of dying between ages 30 and 70 years during 2001, 2006, and 2013 was calculated by the formula suggested by the World Health Organization. Line graphs were used to depict time trends in age-specific mortality rates over the years in four major NCDs (cardiovascular diseases, cancer, diabetes, and chronic respiratory diseases).

Results:

The age-specific mortality rate because of four NCDs showed a decrease of 51 deaths per 100,000 population from 2001 to 2013. Of the four NCDs, age-specific mortality rate was highest in cardiovascular diseases (238.2/100,000 population) and least in diabetes mellitus (21.9/100,000 population); it was 76.3 and 58.2/100,000 population for cancer and chronic respiratory diseases, respectively. The probability of dying was very less and was almost the same from 30 to 44 years of life and increased steeply after that till 70 years of life; and it was more in males (24%) compared with females (17.4%).

Conclusion:

Although India has shown a decreasing trend in premature mortality because of NCDs in the past decade, the rate of decrease is not on par to achieve the global “25 × 25” target.

Status of fluid and electrolyte absorption in cystic fibrosis

Salt and fluid absorption is a shared function of many of the body's epithelia, but its use is highly adapted to the varied physiological roles of epithelia-lined organs. These functions vary from control of hydration of outward-facing epithelial surfaces to conservation and regulation of total body volume. In the most general context, salt and fluid absorption is driven by active Na(+) absorption. Cl(-) is absorbed passively through various available paths in response to the electrical driving force that results from active Na(+) absorption. Absorption of salt creates a concentration gradient that causes water to be absorbed passively, provided the epithelium is water permeable. Key differences notwithstanding, the transport elements used for salt and fluid absorption are broadly similar in diverse epithelia, but the regulation of these elements enables salt absorption to be tailored to very different physiological needs. Here we focus on salt absorption by exocrine glands and airway epithelia. In cystic fibrosis, salt and fluid absorption by gland duct epithelia is effectively prevented by the loss of cystic fibrosis transmembrane conductance regulator (CFTR). In airway epithelia, salt and fluid absorption persists, in the absence of CFTR-mediated Cl(-) secretion. The contrast of these tissue-specific changes in CF tissues is illustrative of how salt and fluid absorption is differentially regulated to accomplish tissue-specific physiological objectives.

Kinase domain mutations confer resistance to novel inhibitors targeting JAK2V617F in myeloproliferative neoplasms

The transforming JAK2V617F kinase is frequently associated with myeloproliferative neoplasms and thought to be instrumental for the overproduction of myeloid lineage cells. Several small molecule drugs targeting JAK2 are currently in clinical development for treatment in these diseases. We performed a high-throughput in vitro screen to identify point mutations in JAK2V617F that would be predicted to have potential clinical relevance and associated with drug resistance to the JAK2 inhibitor ruxolitinib (INCB018424). Seven libraries of mutagenized JAK2V617F cDNA were screened to specifically identify mutations in the predicted drug-binding region that would confer resistance to ruxolitinib, using a BaF3 cell-based assay. We identified five different non-synonymous point mutations that conferred drug resistance. Cells containing mutations had a 9- to 33-fold higher EC(50) for ruxolitinib compared with native JAK2V617F. Our results further indicated that these mutations also conferred cross-resistance to all JAK2 kinase inhibitors tested, including AZD1480, TG101348, lestaurtinib (CEP-701) and CYT-387. Surprisingly, introduction of the 'gatekeeper' mutation (M929I) in JAK2V617F affected only ruxolitinib sensitivity (fourfold increase in EC(50)). These results suggest that JAK2 inhibitors currently in clinical trials may be prone to resistance as a result of point mutations and caution should be exercised when administering these drugs.

The JAK2V617F oncogene requires expression of inducible phosphofructokinase/fructose-bisphosphatase 3 for cell growth and increased metabolic activity

Myeloproliferative neoplasms are characterized by overproduction of myeloid lineage cells with frequent acquisition of oncogenic JAK2V617F kinase mutations. The molecular mechanisms that regulate energy requirements in these diseases are poorly understood. Transformed cells tend to rely on fermentation instead of more efficient oxidative phosphorylation for energy production. Our data in JAK2V617F-transformed cells show that growth and metabolic activity were strictly dependent on the presence of glucose. Uptake of glucose and cell surface expression of the glucose transporter Glut1 required the oncogenic tyrosine kinase. Importantly, JAK2V617F as well as active STAT5 increased the expression of the inducible rate-limiting enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), which controls glycolytic flux through 6-phosphofructo-1-kinase. PFKFB3 was required for JAK2V617F-dependent lactate production, oxidative metabolic activity and glucose uptake. Targeted knockdown of PFKFB3 also limited cell growth under normoxic and hypoxic conditions and blocked in vivo tumor formation in mice. Overall, these data suggest that inducible PFKFB3 is required for increased growth, metabolic activity and is regulated through active JAK2 and STAT5. Novel therapies that specifically block PFKFB3 activity or expression would, therefore, be expected to inhibit JAK2/STAT5-dependent malignancies and related cancers.

NADPH oxidases regulate cell growth and migration in myeloid cells transformed by oncogenic tyrosine kinases

Transformation by tyrosine kinase oncogenes in myeloid malignancies, including BCR-ABL in chronic myeloid leukemia, FLT3ITD in acute myeloid leukemia (AML) or JAK2V617F in myeloproliferative neoplasms (MPN), is associated with increased growth and cytoskeletal abnormalities. Using targeted approaches against components of the superoxide-producing NADPH-oxidases, including NOX2, NOX4 and the common p22^phox subunit of NOX1-4, myeloid cells were found to display reduced cell growth and spontaneous migration. Consistent with a role of NOX as regulators of membrane proximal signaling events in non-phagocytic cells, NOX2 and NOX4 were not involved in the excess production of intracellular reactive oxygen species and did not significantly increase oxygen consumption. All NOX family members are controlled in part through levels of the rate-limiting substrate NADPH, which was found to be significantly elevated in tyrosine kinase oncogene transformed cells. Also, reduced phosphorylation of the actin filament crosslinking protein MARCKS in response to suppression of p22^phox hints at a novel effector of NOX signaling. MARCKS was also found to be required for increased migration. Overall, these data suggest a model whereby NOX links metabolic NADPH production to cellular events that directly contribute to transformation.

PKA mediates constitutive activation of CFTR in human sweat duct

The cystic fibrosis transmembrane conductance regulator (CFTR) Cl⁻ channels are constitutively activated in sweat ducts. Since phosphorylation-dependent and -independent mechanisms can activate CFTR, we sought to determine the actual mechanism responsible for constitutive activation of these channels in vivo. We show that the constitutively activated CFTR Cl⁻ conductance (gCFTR) in the apical membrane is completely deactivated following α-toxin permeabilization of the basolateral membrane. We investigated whether such inhibition of gCFTR following permeabilization is due to the loss of cytoplasmic glutamate or due to dephosphorylation of CFTR by an endogenous phosphatase in the absence of kinase activity (due to the loss of kinase agonist cAMP, cGMP or GTP through α-toxin pores). In order to distinguish between these two possibilities, we examined the effect of inhibiting the endogenous phosphatase activity with okadaic acid (10⁻⁸ M) on the permeabilization-induced deactivation of gCFTR. We show that okadaic acid (1) inhibits an endogenous phosphatase responsible for dephosphorylating cAMP but not cGMP or G protein-activated CFTR and (2) prevents deactivation of CFTR following permeabilization of the basolateral membrane. These results indicate that distinctly different phosphatases may be responsible for dephosphorylating different kinase-specific sites on CFTR. We conclude that the phosphorylation by PKA alone appears to be primarily responsible for constitutive activation of gCFTR in vivo.

Effect of cytosolic pH on epithelial Na+ channel in normal and cystic fibrosis sweat ducts

The activities of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel and the amiloride-sensitive epithelial Na(+) channel (ENaC) are acutely coordinated in the sweat duct. However, the mechanisms responsible for cross-talk between these ion channels are unknown. Previous studies indicated that luminal pH of sweat ducts varies over 3 pH units and that the cytoplasmic pH affects both CFTR and ENaC. Therefore, using basolaterally alpha-toxin-permeabilized apical membrane preparations of sweat ducts as an experimental system, we tested the hypothesis that the cytosolic pH may mediate the cross-talk between CFTR and ENaC. We showed that while luminal pH had no effect, cytosolic pH acutely affected ENaC activity. That is, acidic pH inhibited, while basic pH activated, ENaC. pH regulation of ENaC appears to be independent of CFTR or endogenous kinase activities because basic pH independently stimulated ENaC (1) in normal ducts even when CFTR was deactivated, (2) in CF ducts that lack CFTR in the plasma membranes and (3) after blocking endogenous kinase activity with staurosporine. Considering the evidence of Na(+)/H(+) exchange (NHE) activity as shown by the expression of mRNA and function of NHE in the basolateral membrane of the sweat duct, we postulate that changes in cytosolic Na(+) ([Na(+)]( i )) may alter cytosolic pH (pH( i )) as salt loads into the cell during electrolyte absorption. These changes may play a role in coordinating the activities of ENaC and CFTR during transepithelial salt transport.

ENaC activity requires CFTR channel function independently of phosphorylation in sweat duct

We previously showed that activation of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) Cl- conductance (gCFTR) supports parallel activation of amiloride-sensitive epithelial Na+ channel (ENaC) in the native human sweat duct. However, it is not clear whether phosphorylated CFTR, phosphorylated ENaC, or only Cl(-) -channel function is required for activation. We used basilaterally alpha-toxin-permeabilized human sweat ducts to test the hypothesis that ENaC activation depends only on Cl(-) -channel function and not on phosphorylation of either CFTR or ENaC. CFTR is classically activated by PKA plus millimolar ATP, but cytosolic glutamate activation of gCFTR is independent of ATP and phosphorylation. We show here that both phosphorylation-dependent (PKA) and phosphorylation-independent (glutamate) activation of CFTR Cl- channel function support gENaC activation. We tested whether cytosolic application of 5 mM ATP alone, phosphorylation by cAMP, cGMP, G-protein dependent kinases (all in the presence of 100 microM ATP), or glutamate could support ENaC activation in the absence of gCFTR. We found that none of these agonists activated gENaC by themselves when Cl- current (I(Cl-)) through CFTR was blocked by: 1) Cl- removal, 2) DIDS inhibition, 3) lowering the ATP concentration to 100 microM (instead of 5 mM required to support CFTR channel function), or 4) mutant CFTR (homozygous DeltaF508 CF ducts). However, Cl- gradients in the direction of absorption supported, while Cl- gradients in the direction of secretion prevented ENaC activation. We conclude that the interaction between CFTR and ENaC is dependent on activated I(Cl-) through CFTR in the direction of absorption (Cl- gradient from lumen to cell). But such activation of ENaC is independent of phosphorylation and ATP. However, reversing I(Cl-) through CFTR in the direction of secretion (Cl- gradient from cell to lumen) prevents ENaC activation even in the presence of I(Cl-) through CFTR.

Cytosolic potassium controls CFTR deactivation in human sweat duct

Absorptive epithelial cells must admit large quantities of salt (NaCl) during the transport process. How these cells avoid swelling to protect functional integrity in the face of massive salt influx is a fundamental, unresolved problem. A special preparation of the human sweat duct provides critical insights into this crucial issue. We now show that negative feedback control of apical salt influx by regulating the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel activity is key to this protection. As part of this control process, we report a new physiological role of K(+) in intracellular signaling and provide the first direct evidence of acute in vivo regulation of CFTR dephosphorylation activity. We show that cytosolic K(+) concentration ([K(+)](c)) declines as a function of increasing cellular NaCl content at the onset of absorptive activity. Declining [K(+)](c) cause parallel deactivation of CFTR by dephosphorylation, thereby limiting apical influx of Cl(-) (and its co-ion Na(+)) until [K(+)](c) is stabilized. We surmise that [K(+)](c) stabilizes when Na(+) influx decreases to a level equal to its efflux through the basolateral Na(+)-K(+) pump thereby preventing disruptive changes in cell volume.

Normal CFTR Activity and Reversed Skin Potentials in Pseudohypoaldosteronism

Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) Cl(-) channel function is required for activating amiloride-sensitive epithelial Na(+) channels (ENaC) in salt-absorbing human sweat duct. It is unclear whether ENaC channel function is also required for CFTR activation. The dysfunctional ENaC mutations in type-1 pseudohypoaldosteronism (PHA-1) provided a good opportunity to study this phenomenon of ion channel interaction between CFTR and ENaC. The PHA-1 ducts completely lacked spontaneous ENaC conductance (gENaC). In contrast, the normal ducts showed large spontaneous gENaC (46 +/- 10 ms, mean +/- SE: ). After permeabilization of the basolateral membrane with alpha-toxin, cAMP + ATP activation of CFTR Cl(-) conductance (gCFTR) or alkalinization of cytosolic pH (6.8 to 8.5) stimulated gENaC of normal but not PHA-1 ducts. In contrast, both spontaneous gCFTR in intact ducts and (cAMP + ATP)-activated gCFTR of permeabilized ducts appeared to be similar in normal and PHA-1 subjects. Lack of gENaC completely blocked salt absorption and caused dramatic reversal of skin potentials associated with pilocarpine-induced sweat secretion from significantly negative in normal subjects (-13 +/- 7.0 mV) to significantly positive (+22 +/- 11.0 mV) in PHA-1 patients. We conclude that virtual lack of ENaC in PHA-1 ducts had little effect on CFTR activity and that the positive skin potentials could potentially serve as a diagnostic tool to identify type-1 pseudohypoaldosteronism.

Effects of a new cystic fibrosis transmembrane conductance regulator inhibitor on Cl- conductance in human sweat ducts

Effective and specific inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel in epithelia has long been needed to better understand the role of anion movements in fluid and electrolyte transport. Until now, available inhibitors have required high concentrations, usually in the millimolar or high micromolar range, to effect even an incomplete block of channel conductance. These inhibitors, including 5-nitro-2(3-phenylpropyl-amino)benzoate (NPPB), bumetamide, glibenclamide and DIDS, are also relatively non-specific. Recently a new anion channel inhibitor, a thiazolidinone derivative, termed CFTRInh-172 has been synthesized and introduced with apparently improved inhibitory properties as shown by effects on anion conductance expressed in cell lines and on secretion in vivo. Here, we assay the effect of this inhibitor on a purely salt absorbing native epithelial tissue, the freshly isolated microperfused human sweat duct, known for its inherently high expression of CFTR. We found that the inhibitor at a maximum dose limited by its aqueous solubility of 5 microm partially blocked CFTR when applied to either surface of the membrane; however, it may be somewhat more effective from the cytosolic side (approximately 70% inhibition). It may also partially inhibit Na+ conductance. The inhibition was relatively slow, with a half time for maximum effect of about 3 min, and showed very slow reversibility. Results also suggest that CFTR Cl- conductance (GCl) was blocked in both apical and basal membranes. The inhibitor appears to exert some effect on Na+ transport as well.

Control of dynamic CFTR selectivity by glutamate and ATP in epithelial cells

Cystic fibrosis is caused by mutations in cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel. Phosphorylation and ATP hydrolysis are generally believed to be indispensable for activating CFTR. Here we report phosphorylation- and ATP-independent activation of CFTR by cytoplasmic glutamate that exclusively elicits Cl-, but not HCO3-, conductance in the human sweat duct. We also report that the anion selectivity of glutamate-activated CFTR is not intrinsically fixed, but can undergo a dynamic shift to conduct HCO3- by a process involving ATP hydrolysis. Duct cells from patients with DeltaF508 mutant CFTR showed no glutamate/ATP activated Cl- or HCO3- conductance. In contrast, duct cells from heterozygous patients with R117H/DeltaF508 mutant CFTR also lost most of the Cl- conductance, yet retained significant HCO3- conductance. Hence, not only does glutamate control neuronal ion channels, as is well known, but it can also regulate anion conductance and selectivity of CFTR in native epithelial cells. The loss of this uniquely regulated HCO3- conductance is most probably responsible for the more severe forms of cystic fibrosis pathology.

Functional interaction of CFTR and ENaC in sweat glands

The cystic fibrosis transmembrane conductance regulator (CFTR) plays a significant role in transepithelial salt absorption as well as secretion by a number of epithelial tissues including sweat glands, airways and intestine. Early studies suggested that in absorption significant cross talk occurs between CFTR Cl(-) channels and epithelial Na(+) channels (ENaC). Studies based primarily on cultured cells of the airways and on ex vivo expression systems suggested that activating CFTR inhibits ENaC channels so that activation of CFTR and deactivation of ENaC seem reciprocal. Lack of CFTR Cl(-) conductance (g(CFTR)) in the plasma membranes was seen to enhance ENaC conductance (g(ENaC)) and Na(+) absorption from the airway surface liquid causing airway pathology in cystic fibrosis (CF). To determine if these events hold true for a purely absorptive epithelium, we investigated the role of CFTR in regulating g(ENaC) in native human sweat gland ducts. After permeabilizing the basilateral membrane of the duct with alpha-toxin, the relative activities of ENaC and CFTR in the apical membrane were characterized by correlating the effect of activating CFTR with ENaC function. We found that in contrast to reciprocal activities, activating g(CFTR) by either cAMP, cGMP or the G-proteins plus 5 mM ATP was accompanied by a concomitant activation, not inhibition, of g(ENaC). The activation of g(ENaC) appeared to be critically dependent on CFTR Cl(-) channel function because removal of Cl(-) from the medium, blockage of CFTR with inhibitor DIDS or the absence of CFTR in the DeltaF508 CF ducts prevented activation of g(ENaC) by cAMP, GMP or G-proteins. Most significantly, g(ENaC) was dramatically reduced, not increased, in CF as compared to non-CF sweat ducts. These results showed that lack of CFTR in the plasma membranes is not characteristically coupled to elevated ENaC activity or to increased Na(+) absorption in CF epithelial cells. Not only are CFTR and ENaC activated together in duct salt absorption, but ENaC activation depends on functioning CFTR. NaCl is poorly absorbed in the CF duct because CFTR activity appears to impose a loss of ENaC activity as well.

Effect of anion transport blockers on CFTR in the human sweat duct

Cystic fibrosis transmembrane conductance regulator (CFTR) is a protein kinase A (PKA) and ATP regulated Cl- channel. Studies using mostly ex vivo systems suggested diphenylamine-2-carboxylate (DPC), 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and glybenclamide inhibit CFTR Cl- conductance (CFTR GCl). However, the properties of inhibition in a native epithelial membrane have not been well defined. The objective of this study was to determine and compare the inhibitory properties of the aforementioned inhibitors as well as the structurally related anion-exchange blockers (stilbenes) including 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS), 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS) in the microperfused intact and basilaterally permeabilized native sweat duct epithelium. All of these inhibitors blocked CFTR in a dose-dependent manner from the cytoplasmic side of the basilaterally permeabilized ducts, but none of these inhibitors blocked CFTR GCl from the luminal surface. We excluded inhibitor interference with a protein kinase phosphorylation activation process by "irreversibly" thiophosphorylating CFTR prior to inhibitor application. We then activated CFTR GCl by adding 5 mM ATP. At a concentration of 10(-4) M, NPPB, DPC, glybenclamide, and DIDS were equipotent and blocked approximately 50% of irreversibly phosphorylated and ATP-activated CFTR GCl (DIDS = 49 +/- 10% > NPPB = 46 +/- 10% > DPC = 38 +/- 7% > glybenclamide = 34 +/- 5%; values are mean +/- SE expressed as % inhibition from the control). The degree of inhibition may be limited by inhibitor solubility limits, since DIDS, which is soluble to 1 mM concentration, inhibited 85% of CFTR GCl at this concentration. All the inhibitors studied primarily blocked CFTR from the cytoplasmic side and all inhibition appeared to be independent of metabolic and phosphorylation processes.

Stereospecific synthesis of trans-arachidonic acids

An effective synthesis is described for the preparation of all four mono trans isomers of arachidonic acid via deoxidation of epoxide precursors with lithium diphenylphosphide and quaternization with methyl iodide.

Selective activation of cystic fibrosis transmembrane conductance regulator Cl- and HCO3- conductances

While cystic fibrosis transmembrane conductance regulator (CFTR) is well known to function as a Cl(-) channel, some mutations in the channel protein causing cystic fibrosis (CF) disrupt another vital physiological function, HCO(3)(-) transport. Pathological implications of derailed HCO(3)(-) transport are clearly demonstrated by the pancreatic destruction that accompany certain mutations in CF. Despite the crucial role of HCO(3)(-) in buffering pH, little is known about the relationship between cause of CF pathology and the molecular defects arising from specific mutations. Using electrophysiological techniques on basolaterally permeabilized preparations of microperfused native sweat ducts, we investigated whether: a) CFTR can act as a HCO(3)(-) conductive channel, b) different conditions for stimulating CFTR can alter its selectivity to HCO(3)(-) and, c) pancreatic insufficiency correlate with HCO(3)(-) conductance in different CFTR mutations. We show that under some conditions stimulating CFTR can conduct HCO(3)(-). HCO(3)(-) conductance in the apical plasma membranes of sweat duct appears to be mediated by CFTR and not by any other Cl(-) channel because HCO(3)(-) conductance is abolished when CFTR is: a) deactivated by removing cAMP and ATP, b) blocked by 1 mM DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid) in the cytoplasmic bath and, c) absent in the plasma membranes of DeltaF508 CF ducts. Further, the HCO(3)(-)/Cl(-) selectivity of CFTR appears to be dependent on the conditions of stimulating CFTR. That is, CFTR activated by cAMP + ATP appears to conduct both HCO(3)(-) and Cl(-) (with an estimated selectivity ratio of 0.2 to 0.5). However, we found that in the apparent complete absence of cAMP and ATP, cytoplasmic glutamate activates CFTR Cl(-) conductance without any HCO(3)(-) conductance. Glutamate activated CFTR can be induced to conduct HCO(3)(-) by the addition of ATP without cAMP. The non-hydrolysable AMP-PNP (5'-adenylyl imidodiphosphate) cannot substitute for ATP in activating HCO(3)(-) conductance. We also found that a heterozygous R117H/DeltaF508 CFTR sweat duct retained significant HCO(3)(-) conductance while a homozygous DeltaF508 CFTR duct showed virtually no HCO(3)(-) conductance. While we suspect that the conditions described here are not optimal for selectively activating CFTR Cl(-) and HCO(3)(-) conductances, we surmise that CFTR may be subject to dramatic alterations in its conductance, at least to these two anions under distinctly different physiological conditions which require distinctly different physiological functions. That is physiologically, CFTR may exhibit Cl(-) conductance with and/or without HCO(3)(-) conductance. We also surmise that the severity of the pathogenesis in CF is closely related to the phenotypic ability of a mutant CFTR to express a HCO(3)(-) conductance.

cAMP-independent phosphorylation activation of CFTR by G proteins in native human sweat duct

It is generally believed that cAMP-dependent phosphorylation is the principle mechanism for activating cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels. However, we showed that activating G proteins in the sweat duct stimulated CFTR Cl(-) conductance (G(Cl)) in the presence of ATP alone without cAMP. The objective of this study was to test whether the G protein stimulation of CFTR G(Cl) is independent of protein kinase A. We activated G proteins and monitored CFTR G(Cl) in basolaterally permeabilized sweat duct. Activating G proteins with guanosine 5'-O-(3-thiotriphosphate) (10-100 microM) stimulated CFTR G(Cl) in the presence of 5 mM ATP alone without cAMP. G protein activation of CFTR G(Cl) required Mg(2+) and ATP hydrolysis (5'-adenylylimidodiphosphate could not substitute for ATP). G protein activation of CFTR G(Cl) was 1) sensitive to inhibition by the kinase inhibitor staurosporine (1 microM), indicating that the activation process requires phosphorylation; 2) insensitive to the adenylate cyclase (AC) inhibitors 2',5'-dideoxyadenosine (1 mM) and SQ-22536 (100 microM); and 3) independent of Ca(2+), suggesting that Ca(2+)-dependent protein kinase C and Ca(2+)/calmodulin-dependent kinase(s) are not involved in the activation process. Activating AC with 10(-6) M forskolin plus 10(-6) M IBMX (in the presence of 5 mM ATP) did not activate CFTR, indicating that cAMP cannot accumulate sufficiently to activate CFTR in permeabilized cells. We concluded that heterotrimeric G proteins activate CFTR G(Cl) endogenously via a cAMP-independent pathway in this native absorptive epithelium.

Apical heterotrimeric g-proteins activate CFTR in the native sweat duct

Other than the fact that the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel can be activated by cAMP dependent kinase (PKA), little is known about the signal transduction pathways regulating CFTR. Since G-proteins play a principal role in signal transduction regulating several ion channels [4, 5, 9], we sought to test whether G-proteins control CFTR Cl- conductance (CFTR G(Cl)) in the native sweat duct (SD). We permeabilized the basolateral membrane with alpha-toxin so as to manipulate cytosolic nucleotides. We activated G-proteins and monitored CFTR G(Cl) activity as described earlier [20, 23, 25]. We now show that activating G-proteins with GTP-gamma-S (100 microm) also activates CFTR G(Cl) in the presence of 5 mm ATP alone (without exogenous cAMP). GTP-gamma-S increased CFTR G(Cl) by 44 +/- 20 mS/cm(2) (mean +/- se; n = 7). GDP (10 mm) inhibited G-protein activation of CFTR G(Cl) even in the presence of GTP-gamma-S. The heterotrimeric G-protein activator (AlF(4-) in the cytoplasmic bath activated CFTR G(Cl) (increased by 51.5 +/- 9.4 mS/cm(2) in the presence of 5 mm ATP without cAMP, n = 6), the magnitude of which was similar to that induced by GTP-gamma-S. Employing immunocytochemical-labeling techniques, we localized Galphas, Galphai, Galphaq, and Gbeta at the apical membranes of the sweat duct. Further, we showed that the mutant CFTR G(Cl) in ducts from cystic fibrosis (CF) subjects could be partially activated by G-proteins. The magnitude of mutant CFTR G(Cl) activation by G-proteins was smaller as compared to non-CF ducts but comparable to that induced by cAMP in CF ducts. We conclude that heterotrimeric G-proteins are present in the apical membrane of the native human sweat duct which may help regulate salt absorption by controlling CFTR G(Cl) activity.

Activation of the epithelial Na+ channel (ENaC) requires CFTR Cl- channel function

It is increasingly being recognized that cells coordinate the activity of separate ion channels that allow electrolytes into the cell. However, a perplexing problem in channel regulation has arisen in the fatal genetic disease cystic fibrosis, which results from the loss of a specific Cl- channel (the CFTR channel) in epithelial cell membranes. Although this defect clearly inhibits the absorption of Na+ in sweat glands, it is widely accepted that Na+ absorption is abnormally elevated in defective airways in cystic fibrosis. The only frequently cited explanation for this hypertransport is that the activity of an epithelial Na+ channel (ENaC) is inversely related to the activity of the CFTR Cl- channel. However, we report here that, in freshly isolated normal sweat ducts, ENaC activity is dependent on, and increases with, CFTR activity. Surprisingly, we also find that the primary defect in Cl- permeability in cystic fibrosis is accompanied secondarily by a Na+ conductance in this tissue that cannot be activated. Thus, reduced salt absorption in cystic fibrosis is due not only to poor Cl- conductance but also to poor Na+ conductance.

Bumetanide blocks CFTR GCl in the native sweat duct

Bumetanide is well known for its ability to inhibit the nonconductive Na+-K+-2Cl- cotransporter. We were surprised in preliminary studies to find that bumetanide in the contraluminal bath also inhibited NaCl absorption in the human sweat duct, which is apparently poor in cotransporter activity. Inhibition was accompanied by a marked decrease in the transepithelial electrical conductance. Because the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel is richly expressed in the sweat duct, we asked whether bumetanide acts by blocking this anion channel. We found that bumetanide 1) significantly increased whole cell input impedance, 2) hyperpolarized transepithelial and basolateral membrane potentials, 3) depolarized apical membrane potential, 4) increased the ratio of apical-to-basolateral membrane resistance, and 5) decreased transepithelial Cl- conductance (GCl). These results indicate that bumetanide inhibits CFTR GCl in both cell membranes of this epithelium. We excluded bumetanide interference with the protein kinase A phosphorylation activation process by "irreversibly" phosphorylating CFTR [by using adenosine 5'-O-(3-thiotriphosphate) in the presence of a phosphatase inhibition cocktail] before bumetanide application. We then activated CFTR GCl by adding 5 mM ATP. Bumetanide in the cytoplasmic bath (10(-3) M) inhibited approximately 71% of this ATP-activated CFTR GCl, indicating possible direct inhibition of CFTR GCl. We conclude that bumetanide inhibits CFTR GCl in apical and basolateral membranes independent of phosphorylation. The results also suggest that >10(-5) M bumetanide cannot be used to specifically block the Na+-K+-2Cl- cotransporter.

Cytosolic pH regulates GCl through control of phosphorylation states of CFTR

Our objective in this study was to determine the effect of changes in luminal and cytoplasmic pH on cystic fibrosis transmembrane regulator (CFTR) Cl- conductance (GCl). We monitored CFTR GCl in the apical membranes of sweat ducts as reflected by Cl- diffusion potentials (VCl) and transepithelial conductance (GCl). We found that luminal pH (5.0-8.5) had little effect on the cAMP/ATP-activated CFTR GCl, showing that CFTR GCl is maintained over a broad range of extracellular pH in which it functions physiologically. However, we found that phosphorylation activation of CFTR GCl is sensitive to intracellular pH. That is, in the presence of cAMP and ATP [adenosine 5'-O-(3-thiotriphosphate)], CFTR could be phosphorylated at physiological pH (6.8) but not at low pH (approximately 5.5). On the other hand, basic pH prevented endogenous phosphatase(s) from dephosphorylating CFTR. After phosphorylation of CFTR with cAMP and ATP, CFTR GCl is normally deactivated within 1 min after cAMP is removed, even in the presence of 5 mM ATP. This deactivation was due to an increase in endogenous phosphatase activity relative to kinase activity, since it was reversed by the reapplication of ATP and cAMP. However, increasing cytoplasmic pH significantly delayed the deactivation of CFTR GCl in a dose-dependent manner, indicating inhibition of dephosphorylation. We conclude that CFTR GCl may be regulated via shifts in cytoplasmic pH that mediate reciprocal control of endogenous kinase and phosphatase activities. Luminal pH probably has little direct effect on these mechanisms. This regulation of CFTR may be important in shifting electrolyte transport in the duct from conductive to nonconductive modes.

Cystic fibrosis affects specific cell type in sweat gland secretory coil

The sweat gland has three distinct cell types: a myoepithelial (ME) cell, a beta-adrenergic-insensitive (beta-I) cell, and a beta-adrenergic-sensitive (beta-S) cell. Using intracellular microelectrodes, we sought to functionally identify the specific cell type(s) affected in cystic fibrosis (CF). We found that in CF secretory coils 1) the ME calls are unaffected, as indicated by normal cell membrane potentials and spontaneous and cholinergically induced depolarizing potentials, 2) the beta-I cells showed normal physiological properties, including a relatively smaller cell membrane potential (approx -25 mV) and a Ba(2+)-inhibitable cholinergic response, and, in contrast, 3) the beta-S cell is abnormal, as shown by the lack of a beta-adrenergically activated cystic fibrosis transmembrane conductance regulator (CFTR) Cl- conductance (GCl). Lack of CFTR GCl in this cell type does not affect either the magnitude of cell membrane potential (approx -56 mV) or the relative cell membrane GCl or the cholinergic response, as compared with that of normal beta-S cells. We conclude that, of the three cell types in secretory coil, only the beta-S cell is specifically affected in the CF secretory tissue of the human sweat gland.

Effect of immunotherapy on sCD23 levels in patients allergic to Hymenoptera venom

BACKGROUND

sCD23 is the designation given to the low affinity IgE receptor. The soluble fragment of this receptor (sCD23) participates in the regulation of IgE synthesis.

OBJECTIVE

The purpose of this study is to examine the effect of a venom immunotherapy regimen on sCD23 levels.

METHODS

We measured sCD23 levels by ELISA in Hymenoptera venom-allergic patients (positive skin tests and a history of systemic reactions to Hymenoptera sting) in serial sera collected over a course of venom immunotherapy with a mean duration of 54 months. Mean pre-sCD23 and post-sCD23 levels were compared using a Student's two-tailed t test.

RESULTS

sCD23 levels were found to be unchanged over the course of venom immunotherapy.

CONCLUSIONS

This is the first longitudinal study that has been done. It suggests that while both immunotherapy and sCD23 are known to be involved in the regulations of IgE synthesis in the atopic patient, the immunomodulation seen in venom immunotherapy is not mediated through sCD23 in any simple regulatory manner.

Distinct cellular mechanisms of cholinergic and beta-adrenergic sweat secretion

The cholinergic and beta-adrenergic sweat secretions from human sweat glands differ with respect to secretory rates and their susceptibility to cystic fibrosis (CF). Using the cultured beta-adrenergic-sensitive sweat secretory cell, we sought to determine the intracellular electrophysiological mechanisms underlying these functional differences. We found that the cholinergic agonist methacholine (10(-6) M) induced a Ca(2+)-dependent biphasic membrane potential (Vm) response: an initial hyperpolarization and a secondary depolarization. The initial hyperpolarization was independent of bath Cl- and dependent on transmembrane K+ gradient. However, the secondary depolarization of Vm was dependent on bath Cl-. In contrast, the beta-adrenergic agonist isoproterenol (10(-5) M) induced a monophasic depolarization of Vm. This depolarization was 1) dependent on bath Cl-, 2) independent of K+ conductance (GK) blocker Ba2+ (5mM), 3) unaffected by the methacholine-induced secondary depolarization of Vm, and 4) absent in cells derived from CF subjects. These results indicated that the cholinergic agonist-induced secretion mainly involves the activation of Ca(2+)-dependent GK and Cl- conductance (GCl), whereas the beta-adrenergic secretion seems to mainly depend on the activation of cystic fibrosis transmembrane conductance regulator-GCl.

Hydrolytic and nonhydrolytic interactions in the ATP regulation of CFTR Cl- conductance

Previously, we showed in the native sweat duct that, in the presence of 0.1-0.5 mM ATP, nonhydrolyzable ATP analogue adenosine 5'-adenylylimidodiphosphate (AMP-PNP) can activate cystic fibrosis transmembrane conductance regulator Cl- conductance (CFTR GCl) (15). The objective of this study is to determine if 1) nonhydrolytic ATP binding alone can activate CFTR GCl after stable phosphorylation [in the presence of adenosine 5'-O-(3-thiotriphosphate) and phosphatase inhibition cocktail] of CFTR or 2) an ATP hydrolysis (in addition to phosphorylation) is required to support subsequent nonhydrolytic ATP regulation of CFTR GCl. We show that stably phosphorylated CFTR could only be activated by AMP-PNP in the presence of a small background ATP concentration. However, AMP-PNP can sustain previously activated CFTR GCl in the absence of ATP, even though Mg2+ is required for phosphorylation activation of CFTR GCl. However, once stably phosphorylated, ATP activation of CFTR GCl is independent of Mg2+. Our results show that both hydrolytic and nonhydrolytic interactions regulate CFTR GCl in vivo. Nonhydrolytic ATP interaction plays a significant role in both activation and deactivation of CFTR GCl.

In vitro release of soluble CD23 by human lymphocytes in ragweed-sensitive versus nonatopic patients following stimulation with ragweed antigen E

BACKGROUND

Soluble CD23 is the proteolytic cleavage product of the low affinity receptor (FcERII). Functions of CD23 and its soluble products may include upregulation of IgE production and stimulation of B lymphocyte growth.

METHODS

Soluble CD23 was quantitated in supernatants of lymphocytes from nine ragweed-sensitive and eight nonatopic subjects stimulated in vitro by antigen E (amb Al), crude ragweed extract, and pokeweed mitogen (PWM).

RESULTS

Although PWM stimulation produced no significant difference between groups, sCD23 release was significantly elevated in the cells of nonatopic patients stimulated with antigen E and crude ragweed extract (P less than .05).

CONCLUSIONS

This finding supports the concept of separate pathways of activation by antigen and mitogen for sCD23 release and suggests ragweed-sensitive and nonatopic patients have fundamental differences in the response of sCD23 release to ragweed antigen stimulation.

Failure of the cystic fibrosis transmembrane conductance regulator to conduct ATP

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride ion channel regulated by protein kinase A and adenosine triphosphate (ATP). Loss of CFTR-mediated chloride ion conductance from the apical plasma membrane of epithelial cells is a primary physiological lesion in cystic fibrosis. CFTR has also been suggested to function an an ATP channel, although the size of the ATP anion is much larger than the estimated size of the CFTR pore. ATP was not conducted through CFTR in intact organs, polarized human lung cell lines, stably transfected mammalian cell lines, or planar lipid bilayers reconstituted with CFTR protein. These findings suggest that ATP permeation through the CFTR is unlikely to contribute to the normal function of CFTR or to the pathogenesis of cystic fibrosis.

Deactivation of CFTR-Cl conductance by endogenous phosphatases in the native sweat duct

Cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation-activated Cl channel. However, very little is known about the endogenous mechanism(s) of deactivation of CFTR-Cl conductance (CFTR-GCl) in vivo. We studied the action of endogenous phosphatases in regulation of the adenosine 3',5'-cyclic monophosphate (cAMP)- and ATP-induced CFTR-GCl in the apical membrane of microperfused preparations of basolaterally permeabilized native sweat duct. Activation of CFTR-GCl was monitored by measuring the apical Cl diffusion potentials and GCl, which spontaneously deactivated on removal of cAMP. This spontaneous loss of CFTR-GCl activity could be prevented by a cocktail of phosphatase inhibitors (fluoride, vanadate, and okadaic acid). We studied the effects of each of these phosphatase antagonists on the rate of deactivation of CFTR-GCl after cAMP washout. In contrast to vanadate or fluoride, okadaic acid virtually prevented deactivation of CFTR-GCl after cAMP washout. We conclude that either or both protein phosphatases 1 and 2A are responsible for the dephosphorylation deactivation of CFTR-GCl in vivo.

Serum IgE in patients with human immunodeficiency virus infection

BACKGROUND

Dysregulation of IgE synthesis has been noted in the past in several immunodeficiency states. More recently, analysis of IgE synthesis and atopy in patients who are infected with the human immunodeficiency virus (HIV) has been conflicting.

OBJECTIVE

To determine whether IgE dysregulation occurs in HIV-infected patients and if so, whether this dysregulation is antigen-specific and accompanied by any significant changes in T and B cell markers.

METHODS

Thirty-six HIV-infected patients were enrolled in the study. Twenty-nine patients completed the study. All patients completed an allergy questionnaire and physical examination. Interval visits occurred every 3 months. Blood was obtained at baseline and every 3 months for total IgE, antigen-specific IgE to eight environmental allergens and lymphocyte markers. Study was not blinded.

RESULTS

Analysis of results at baseline and 1 year revealed a subset of patients who had marked elevations in serum IgE protein. This increase was not accompanied by any detectable antigen-specific IgE to the measured allergens nor was any significant change noted in lymphocyte markers. Student's paired t tests were used for data analysis.

CONCLUSION

In a subset of patients with HIV infection, acquired dysregulation of IgE synthesis occurs that results in increased circulatory levels of IgE protein not attributable to atopic allergens or associated with detectable changes in lymphocyte markers.

Intracellular Cl activity: evidence of dual mechanisms of cl absorption in sweat duct

The human sweat duct (SD) reabsorbs NaCl from lumen to blood over a wide range of luminal concentrations. The physiological strategies employed by the SD to cope with such extreme transport loads remain elusive. When we employed intracellular Cl-sensitive microelectrodes, we found that at high (150 mM) luminal NaCl concentrations ([NaCl]) transcellular Cl absorption occurs through passive diffusion that is evidenced by a large Cl conductance (GCl) in both cell membranes and by a favorable electrochemical driving force for Cl (delta psi Cl) across the apical and basolateral membranes. However, lowering the luminal [NaCl] to 15 mM markedly altered the electrochemical gradient for Cl and reversed the direction of delta psi Cl. Under these conditions, passive absorption of Cl was not feasible, so that Cl can only be absorbed by a nonconductive transport carrier. We surmise that, in the face of such changes in delta psi Cl as a function of luminal [NaCl], continuous transcellular Cl transport in SD could only be sustained if both electroconductive and carrier-mediated Cl transport are present in the SD.

Rapid regulation of electrolyte absorption in sweat duct

Even though the same Cl channel (CFTR) is common to certain fluid transport functions that are oppositely directed, i.e., secretion and absorption, only fluid secretion has clearly been shown to be acutely regulated. It is now clear that fluid secretion activated by beta-adrenergic stimulation is controlled by cAMP-mediated opening and closing of CFTR-Cl channels. Since the conductance of the human sweat duct is almost wholly due to CFTR-Cl conductance (CFTR-GCl), we sought to determine whether salt absorption via CFTR-Cl channels could also be subject to acute regulation in this purely absorptive epithelium. After alpha-toxin permeabilization, we found that addition of cAMP resulted in a large increase in Cl diffusion potentials across the apical membrane and a more than twofold increase in the average membrane conductance. Since the cAMP effects were dependent on Cl alone, not on Na, and since apical Cl conductance appears to be almost exclusively comprised of CFTR-GCl, we surmise that this form of electrolyte absorption like secretion is also subject to acute control through CFTR-GCl. Acute regulation of absorption involves both activation by phosphorylation (PKA) and inactivation by dephosphorylation (unknown endogenous phosphatase) of CFTR. Phosphorylation of CFTR was shown by the facts that CFTR-GCl could be activated by cAMP and inhibited by the kinase antagonist staurosporine, or by removal of either substrate ATP or Mg2+ cofactor. Inactivation of CFTR-GCl by endogenous phosphatase(s) was indicated by a spontaneous but reversible loss of CFTR-GCl upon removal of cAMP. Such loss of CFTR-GCl activity could be prevented either by application of phosphatase inhibitors or by using phosphatase-resistant ATP-gamma-S as substrate to phosphorylate CFTR. We surmise that absorptive function is subject to rapid regulation which can be switched "on" and "off" acutely by a control system that is common to both absorptive and secretory processes and that this control is crucial to switching between conductive and nonconductive transport mechanisms during salt absorption.

Cortisol levels, immune status, and mood in homosexual men with and without HIV infection

OBJECTIVE

Alteration in cortisol levels has been reported in HIV infection and may be related to levels of psychiatric distress and immune function. The goals of this study were to assess cortisol levels in subjects with HIV infection and to determine whether stress-related activation of the hypothalamic-pituitary-adrenal (HPA) axis results in compromised immune function.

METHOD

As part of a longitudinal study, the authors assessed urinary free cortisol levels of HIV-positive and HIV-negative homosexual men at four time points during a period of 2 years. Subjects' scores on the Hamilton depression and anxiety rating scales, medical stage of HIV infection, and CD4+ and CD8+ cell counts were also assessed. Repeated measures analysis of variance was used to determine whether subjects' cortisol levels at the four time points differed according to their serological status. Pearson correlation coefficients were computed to examine the relationships among mood ratings, cortisol levels, medical stages, and cell counts.

RESULTS

Cortisol levels did not differ significantly between the HIV-positive and the HIV-negative subjects and were not associated with stage of medical illness in HIV infection. An association between cortisol level and depressed and anxious mood was found only at the first assessment. Cortisol level was not associated with CD4+ cell count in either group of subjects.

CONCLUSIONS

There were no significant elevations of cortisol levels in the HIV-infected subjects, nor was there consistent evidence for stress-related activation of the HPA axis in either the HIV-positive or the HIV-negative subjects.

Elevated levels of soluble CD54 (ICAM-1) in human immunodeficiency virus infection

Soluble CD54 levels in sera were quantitated in asymptomatic intravenous drug users, homosexuals, and patients with lymphadenopathy, AIDS-related complex, or acquired immunodeficiency syndrome. Soluble CD54 levels were elevated in human immunodeficiency virus (HIV)-seronegative asymptomatic intravenous drug users, reflecting infections like cytomegalovirus, Epstein-Barr virus, and hepatitis B virus. The sera of human immunodeficiency virus-seropositive groups of patients also had elevated levels of soluble CD54, reflecting infections like cytomegalovirus and human immunodeficiency virus infection.

Control of CFTR chloride conductance by ATP levels through non-hydrolytic binding

Site-specific mutation and membrane reconstitution experiments provide compelling evidence that the product of the gene which is at fault in the disease cystic fibrosis, termed the cystic fibrosis transmembrane conductance regulator (CFTR), is a small-conductance chloride channel activated by phosphorylation. As transport of chloride ions is passive, the predicted presence of two nucleotide-binding domains in CFTR seems as puzzling as a report that ATP hydrolysis is essential to activate the channel. We now find that in the sweat duct, which expresses high levels of CFTR and has a very high Cl- conductance, intracellular concentrations of ATP must be about normal (5 mM) for activation of this conductance, apparently by a non-hydrolytic, perhaps allosteric, mechanism. This passive dependence on ATP should mean that even a modest depletion of cell energy levels will significantly lower the energy demands of electrolyte transport by decreasing chloride conductance. We believe this direct coupling between cellular ATP levels and chloride channel activity is an adaptive mechanism to protect the tissue from damage resulting from excessive energy depletion.

cAMP activation of CF-affected Cl- conductance in both cell membranes of an absorptive epithelium

Cystic fibrosis (CF) is characterized by abnormal epithelial Cl- conductance (GCl). In vitro studies that have shown that cAMP regulation is an intrinsic property of the CF-affected GCl(CF-GCl) have been carried out previously on cultured secretory cells and on nonepithelial cells. Even though GCl in absorption is defective in CF, a clear demonstration of cAMP regulation of CF-GCl in a purely absorptive tissue is lacking. We studied the cAMP regulation of CF-GCl in the microperfused intact human reabsorptive sweat duct. About 40% of the ducts responded to cAMP (responsive) while the remainder of the ducts did not. In responsive ducts, cAMP-elevating agents: beta-adrenergic agonist isoproterenol (IPR), CPT-cAMP, forskolin, theophylline or IBMX increased Gt by about 2.3-fold (n = no. of ducts = 8). Removal of media Cl-, but not amiloride pretreatment (in the lumen), abolished the cAMP response, indicating exclusive activation of GCl. cAMP activated both apical and basolateral GCl. cAMP hyperpolarized gluconate: Cl- (lumen:bath) transepithelial bionic potentials (delta Vt = -20.3 +/- 5.2 mV, mean +/- SE, n = 9) and transepithelial 3: 1 luminal NaCl dilution diffusion potentials (delta Vt = -8.8 +/- 2.9 mV, n = 5). cAMP activated basolateral GCl as indicated by increased bi-ionic (gluconate:Cl-, bath:lumen) diffusion potentials (by about 12 mV). The voltage divider ratio in symmetric NaCl solutions increased by 60%. Compared to responsive ducts, nonresponsive ducts were characterized by smaller spontaneous transepithelial potentials in symmetrical Ringer's solution (Vt = -6.9 +/- 0.8 mV, n = 24, nonresponsive vs. -19.4 +/- 1.8 mV, n = 22, responsive ducts) but larger bi-ionic potentials (-94 +/- 6 mV, n = 35, nonresponsive vs. -65 +/- 5 mV, n = 17, responsive ducts) and dilution diffusion potentials (-40 +/- 5 mV, n = 11, nonresponsive vs. -29 +/- 3 mV, n = 7, responsive ducts). These results are consistent with an inherently (prestimulus) maximal activation of GCl in nonresponsive ducts and submaximal activation of GCl in responsive ducts. We conclude that cAMP activates CF-GCl which is expressed and abnormal in both apical and basal membranes of this absorptive epithelium in CF.

Effect of foscarnet therapy on human immunodeficiency virus p24 antigen levels in AIDS patients with cytomegalovirus retinitis

Circulating human immunodeficiency virus (HIV) p24 antigen levels were measured in 22 AIDS patients who had detectable serum antigen at baseline after induction and maintenance therapy of foscarnet for cytomegalovirus retinitis in phase I/II multicenter trials. The HIV p24 antigen levels decreased from a baseline value of 199 +/- 236 (mean +/- SD) and 140 pg/mL (median) to 106 +/- 218 and 28 pg/mL after 14 days of foscarnet induction therapy (60 mg/kg every 8 h). During chronic foscarnet maintenance, there was a sustained decrease in mean HIV p24 antigen levels below pre-foscarnet therapy baseline concentrations for a median of 16 weeks after foscarnet induction. These results provide evidence for a sustained clinical antiretroviral effect of chronic foscarnet maintenance therapy, consistent with a recent report that foscarnet-treated AIDS patients live longer than ganciclovir-treated patients.