beta-adrenergic agonists exert their "anti-inflammatory" effects in monocytic cells through the IkappaB/NF-kappaB pathway

In addition to their well-studied bronchodilatory and cardiotonic effects, beta-adrenergic agonists carry anti-inflammatory properties by inhibiting cytokine production by human mononuclear cells. In a model of human promonocytic THP-1 cells stimulated with lipopolysaccharide (LPS), we showed that beta-agonists inhibited tumor necrosis factor-alpha and interleukin-8 production predominantly via the beta(2)-adrenergic receptor through the generation of cAMP and activation of protein kinase A. This effect was reproduced by other cAMP-elevating agents such as prostaglandins and cAMP analogs. Activation and nuclear translocation of the transcription factor nuclear factor-kappaB induced by LPS were inhibited with treatment with beta-agonists, an effect that was prominent at late time points (>1 h). Although the initial IkappaB-alpha degradation induced by LPS was minimally affected by beta-agonists, the latter induced a marked rebound of the cytosolic IkappaB-alpha levels at later time points (>1 h), accompanied by an increased IkappaB-alpha cytoplasmic half-life. This potentially accounts for the observed nuclear factor-kappaB sequestration in the cytoplasmic compartment. We postulate that the anti-inflammatory effects of beta-agonists reside in their capacity to increase cytoplasmic concentrations of IkappaB-alpha, possibly by decreasing its degradation.

Pathologies of power: rethinking health and human rights

The field of health and human rights has grown quickly, but its boundaries have yet to be traced. Fifty-one years after the Universal Declaration of Human Rights, consensus regarding the most promising directions for the future is lacking; however, outcome-oriented assessments lead us to question approaches that rely solely on recourse to formal legal and civil rights. Similarly unpromising are approaches that rely overmuch on appeals to governments: careful study reveals that state power has been responsible for most human rights violations and that most violations are embedded in "structural violence"--social and economic inequities that determine who will be at risk for assaults and who will be shielded. This article advances an agenda for research and action grounded in the struggle for social and economic rights, an agenda suited to public health and medicine, whose central contributions to future progress in human rights will be linked to the equitable distribution of the fruits of scientific advancement. Such an approach is in keeping with the Universal Declaration but runs counter to several of the reigning ideologies of public health, including those favoring efficacy over equity.

Role of NFkappaB in the regulation of macrophage colony stimulating factor by tumor necrosis factor-alpha in ST2 bone stromal cells

Expression of MCSF in bone is important to the regulation of osteoclastogenesis. We show here that tumor necrosis factor-alpha (TNFalpha) increases the production of both soluble (sMCSF) and membrane-bound (mMCSF) macrophage colony stimulating factor by ST2 bone stromal cells. Treatment of ST2 cells with TNFalpha caused sMCSF levels to increase by 394+/-5% from basal; mMCSF rose by 316+/-66% from 30+/-10 per 100,000 cells in the same time. These increases were consistent with increased expression of mRNAs encoding both isoforms. Increases in MCSF mRNA are also seen after stimulation with dexamethasone. To investigate the potential role of NFkappaB in this TNFalpha effect, we treated cells with sodium salicylate (NaS), an inhibitor of NFkappaB translocation. NaS decreased TNFalpha-stimulated NFkappaB activation by 50% as assessed by EMSA. Despite inhibition of NFkappaB signaling, NaS enhanced TNFalpha-stimulated MCSF secretion and did not prevent TNFalpha-stimulated increases in sMCSF mRNA, suggesting that NFkappaB was not involved in TNFalpha effect on the gene. TNFalpha failed to stimulate transcription of a 774 nucleotide MCSF promoter-luciferase reporter transfected into ST2 cells which contained the NFkappaB consensus sequence. Deletion of the seven nucleotides containing the NFkappaB homology response sequence from the MCSF promoter increased basal gene transcription by twofold. TNFalpha thus contributes to an osteoclastogenic environment through upregulation of bone expression of both MCSF isoforms. Our data suggests that NFkappaB is not the major signaling pathway through which this occurs.

Visceral anomalies in prenatally adriamycin-exposed rat fetuses: a model for the VATER association

Adriamycin is teratogenic if given to pregnant rats. A wide range of anomalies involving the gastrointestinal, renal, and cardiovascular systems has been described, similar to the VATER association, yet it is not known if they are identical to the human pattern. The aim of this study was to document the visceral anomalies in rat fetuses exposed to adriamycin and to determine their similarities with the congenital defects in humans with the VATER association. The results revealed a spectrum of very similar anomalies. Furthermore, the characteristics of the tracheo-oesophageal anomalies had a lot of features in common with the human pattern. We conclude that the adriamycin-treated fetal rat is an excellent model for studying the VATER association.

Intrinsic innervation of the oesophagus in fetal rats with oesophageal atresia

Although the aetiology of oesophageal dysmotility after repair of oesophageal atresia and tracheo-oesophageal fistula (OA-TOF) remains controversial, oesophageal dysmotility also is present in isolated TOF or OA before surgery, suggesting a congenital cause. Our previous work with a model of OA-TOF in fetal rats demonstrated an abnormality in the course and branching pattern of the vagus nerve. However, little is known about the intramural nervous components of the atretic oesophagus. The intrinsic innervation of the atretic oesophagus was examined by immunohistological staining to see if there is an abnormality that might account for dysmotility. OA-TOF was induced in fetal rats by injecting adriamycin intraperitoneally into pregnant rats. Forty-eight controls, 40 OA-TOF, and 6 treated fetuses without OA-TOF were recovered. Whole-mount preparations of each oesophagus were stained with fluorescent antibodies against neuron-specific enolase (NSE), vasoactive intestinal peptide (VIP), substance P (SP), and calcitonin gene-related peptide (CGRP). Compared with control fetuses, the density of the nerve plexus, ganglia, and number of cell bodies per ganglion immunostained by NSE, VIP, or SP was significantly reduced in OA-TOF fetuses. CGRP-immunoreactive nerve fibres in the oesophageal wall of both control and OA-TOF animals were found to be connected with extrinsic nerve bundles. No plexus-like nerve fibre network was observed. The results of the present study demonstrated significant abnormalities of the intramural nervous components of the oesophagus in OA-TOF fetal rats, involving both the excitatory (SP-labelled) and inhibitory (VIP-labelled) intramural nerves. These abnormalities may underlie the oesophageal dysmotility seen in OA-TOF patients.

Embryogenesis of tracheal atresia

A spectrum of tracheo-esophageal anomalies has been described in an adriamycin-treated model with common features to the human pattern. Tracheal agenesis was part of this spectrum. It is a rare congenital anomaly that has not been described in embryos. Virgin timed-pregnant Sprague-Dawley rats were injected with adriamycin i.p. at a dose of 2 mg/Kg on days 6-9 of gestation (plug day = day 0). Fetuses were recovered at term and histologic assessment of tracheo-esophageal anomalies was made. Also, embryos were removed on different gestational days and the embryology of these defects was analysed. Two out of sixty-two fetuses and nine out of 180 embryos were identified with tracheal atresia. Type III tracheal atresia was seen in the full-term fetuses with a tracheo-esophageal fistula arising from the origin of the left main bronchus. Day 13 embryos did not show normal tracheal development; instead, the lung buds developed from the ventral aspect of the foregut which continued to the stomach as a lower esophageal segment. A blind ending pouch was seen on the ventral aspect of the upper part of the foregut. The embryogenesis of tracheal atresia was similar to that of esophageal atresia except that the blind upper foregut pouch developed ventrally rather than dorsally.

Tumor necrosis factor activates a nuclear inhibitor of vitamin D and retinoid-X receptors

Tumor necrosis factor-alpha (TNF) is an important contributor to the pathophysiology of bone loss in osteoporosis. Previous work has revealed that TNF inhibits 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) action. We have shown that TNF decreases binding of the vitamin D receptor (VDR) and its heterodimeric partner, the retinoid-x receptor (RXR), to the vitamin D response element (VDRE) of the osteocalcin gene. Here we test the hypothesis that TNF induces a nuclear inhibitor of RXR/VDR binding to DNA and that this inhibitor can have independent effects on RXR. The effect of TNF on RXR and VDR binding to their cognate response elements and stimulation of transcription was studied in VDR deficient CV-1 and COS-7 cells. In CV-1 cells transfected with VDR and RXR expression vectors, TNF-alpha inhibited 1,25(OH)2D3 stimulated transcription of a VDRE-CAT reporter and 9-cis-retinoic acid (9cRA) stimulated transcription of an RXRE-CAT reporter. Inhibition of transcription was associated with decreased binding of VDR and RXR to their cognate response elements. To determine if TNF-alpha induced a nuclear inhibitor of VDR and RXR binding to DNA, nuclear extract was isolated from TNF treated receptor deficient COS cells and mixed with nuclear extract from ligand treated receptor replete COS cells. Receptor binding to DNA was inhibited by the extract from TNF treated COS-7 cells. The inhibitory activity rapidly appeared in nuclear extracts following TNF stimulation. We conclude that TNF activates a nuclear inhibitor of VDR and RXR.

Relationship between esophageal atresia with tracheoesophageal fistula and vertebral anomalies in mammalian embryos

BACKGROUND/PURPOSE

The association of esophageal atresia with tracheoesophageal fistula and vertebral anomalies is well known, although the embryology of the combined defects has not yet been analysed. The present study describes the origin and development of esophageal atresia with tracheoesophageal fistula and vertebral anomalies in embryos using a rat model of VATER association produced by Adriamycin administration.

RESULTS

The lung buds were seen to develop from the laryngotracheal groove but the trachea failed to grow normally and the foregut overgrowth compensated for this failure. The trachea developed by trachealization of the foregut, which continued as a fistula to the lower esophageal segment. The notochord did not separate from the foregut at the correct time (before day 11 in rat embryos, Carnegie stage 11 in human embryos). Overgrowth of the foregut ventrally and caudally carried with it the attached notochord in the same direction leading to abnormal bending of this structure.

CONCLUSION

This irregularity of the notochord may be responsible for abnormal development of the vertebrae.

Tracheomalacia with esophageal atresia and tracheoesophageal fistula in fetal rats

BACKGROUND

Many patients who have esophageal atresia and tracheoesophageal fistula (EA-TEF) have associated tracheomalacia, which is thought to be one of the reasons for respiratory complications after surgical correction of the abnormality.

METHODS

In this study, tracheas from Adriamycin-induced EA-TEF fetal rats were examined histologically and relevant cross-sectional parameters of the tracheas were measured.

RESULTS

The tracheal lumen in tracheomalacia was small and irregular, losing its normal "D" shape. In most rats, the cartilaginous ring was broken into two to four segments, making the trachea lose its rigid support. The submucosa was thickened with prominent bulging of its membranous part into the tracheal lumen. The ratio of the inner luminal cross-sectional area to the outer tracheal cross-sectional area in EA-TEF rats was 15.7%, compared with a control ratio of 47.2%. In EA-TEF rats, the length of the cartilaginous ring was significantly shortened (P < .001), but not the length of membranous trachea, thus resulting in a cartilaginous/membranous (C/M) ratio of 1.55:1, markedly lower than that of normal rats (4.34:1, P < .001). The reduction of anterior-posterior diameter of the tracheal lumen was more marked than that of the transverse diameter.

CONCLUSIONS

These observations suggest that the trachea in EA-TEF rats has a smaller lumen and is more flaccid than normal, making it prone to airway obstruction. The fact that tracheomalacia developed only in fetuses who had EA-TEF indicates that the factors that result in EA-TEF also cause tracheomalacia.

The vagus and recurrent laryngeal nerves in the rodent experimental model of esophageal atresia

BACKGROUND

After surgical correction of their esophageal atresia and tracheoesophageal fistula (EA-TEF), many patients exhibit evidence of esophageal dysmotility. Controversy exists as to whether the esophageal motility disorders result from denervation caused by surgery or from an inherent abnormal innervation of the esophagus.

METHODS

The present study used an Adriamycin-induced EA-TEF fetal rat model to trace the course and branching of both the vagus and recurrent laryngeal nerves. Abnormalities observed in EA-TEF rat fetuses include: (1) fewer branches from both recurrent laryngeal nerves; (2) deviation of the left vagus from its normal course below the aorta, passing behind the fistula to approach and join with the right vagus to form a single nerve trunk on the right side of the esophagus; (3) relatively few branches from the single vagal nerve trunk (composed of fibers of the left and the right vagus) on the surface of the lower esophagus.

CONCLUSIONS

Fetuses affected by EA-TEF have inherent abnormalities in the course and branching pattern of the vagus nerves as they descend through the thorax, culminating in a deficient extrinsic nerve fiber plexus in the lower esophagus. These observations may account for the esophageal motility disorders seen in patients who have EA-TEF even before surgical intervention.

Timing and embryology of esophageal atresia and tracheo-esophageal fistula

BACKGROUND

The embryology of tracheo-esophageal anomalies is controversial. The development of an adriamycin-treated animal model has enabled improved understanding of the embryogenesis of these anomalies. Using this model, we aimed to describe the events leading to esophageal atresia and tracheo-esophageal fistula.

METHODS

Timed-pregnant Sprague-Dawley rats were injected daily with adriamycin intraperitoneally at a dose of 2 mg/Kg on days 6-9 of gestation. Histological sections were prepared from 96 experimental and 34 control rat embryos at 11-14 days gestation (plug day = day 0).

RESULTS

The tracheal bud failed to develop normally from the foregut, leaving the foregut to give origin to both bronchi and differentiate into the respiratory system, and then continue as a fistula to the lower esophageal segment. Dorsal pouching of the proximal foregut, which is seen clearly on day 13, is responsible for the development of the upper esophageal segment.

CONCLUSIONS

We conclude that failure of the tracheal bud to develop normally from the primitive foregut is the main event which leads to the tracheo-esophageal anomalies. As the proximal part of the primitive foregut develops primarily into a trachea rather than an esophagus, the anomaly of the esophagus could be described as agenesis instead of atresia.

Aprotinin, an antifibrinolytic drug, attenuates bradykinin-induced permeability in conscious rats via platelets and neutrophils

Two antifibrinolytic drugs, tranexamic acid (TXA) and aprotinin (APR), are used to improve the recovery of patients following cardiac surgery while reducing blood loss. Their mechanisms of action have yet to be fully understood. To investigate their possible mechanisms of action during cardiopulmonary bypass, we examined (i) the effects of TXA and APR on bradykinin (BK) induced vascular permeability (VP) in conscious rats, (ii) the roles of platelets and neutrophils in this reaction, and (iii) the effects of TXA or APR on BK responses in platelet- or neutrophil-depleted rats. Evans blue dye (EB) was used as the marker of extravasation. The animals were treated with antiplatelet serum for platelet depletion or with methotrexate for neutrophil depletion. In normal rats, BK increased VP in most tissues. Thrombocytopenia and neutropenia also increased basal VP. TXA had no significant effect whereas APR decreased basal VP. In the second series of experiments, APR significantly attenuated BK-induced increases in VP, whereas TXA was completely ineffective. Platelet depletion did not affect BK-induced increases of VP, except for a massive plasma exudation in the lung parenchyma. Neutrophil depletion also had no effect on BK-induced increases of VP, except for an attenuation in the duodenum. In the third and last series of experiments, TXA potentiated the effect of BK in the upper and lower bronchi of platelet-depleted rats, compared with the effects of TXA on BK in normal animals, except in the lung parenchyma, where TXA blocked the increase of VP induced by BK. APR also potentiated the effect of BK in the lower bronchi of platelet-depleted rats. Overall, the inhibitory effect of APR on the VP induced by BK in normal rats was attenuated in platelet-depleted rats. Like TXA, APR blocked the increase of VP induced by BK in the lung parenchyma of platelet-depleted rats. In neutrophil-depleted rats, TXA did not affect the permeabilizing response to BK. In those rats, the inhibitory effect of APR against BK increases of VP was attenuated. These results show that the beneficial effect of APR, but not TXA, following cardiac surgery may be attributed to the inhibition of plasma exudation mediated, in part, by BK. In addition, platelets and neutrophils do not appear to be involved in BK-mediated plasma exudation. However, both cell types are essential for the regulation of basal VP. Finally, the mechanism underlying the protective inhibitory effect of APR on BK-induced increases of VP involves, at least in part, platelets and neutrophils, since the inhibitory effect of APR is attenuated in thrombocytopenic and neutropenic rats. Both cell types are not involved in the action of TXA on VP. Therefore, maintaining platelet and neutrophil counts following cardiopulmonary bypass could enhance the protective effect of APR.

Social scientists and the new tuberculosis

In much of the world, tuberculosis (TB) remains the leading killer of young adults, in spite of the fact that effective chemotherapy has existed for 50 years. The epidemiology of TB, with its persistence in poor countries and resurgence among the poor of many industrialized nations, causes consternation among those charged with protecting the public's health. Two factors, ostensibly biological in nature, are commonly cited to explain this setback: the advent of HIV and the emergence of TB strains resistant to multiple drugs (MDR TB). But the strikingly patterned occurrence of MDR TB-in the United States afflicting those in homeless shelters and in the inner city, for example-speaks to some of the large-scale social forces at work in the new epidemic, which began before the advent of HIV. These forces (which include poverty, economic inequality, political violence, and racism) are examined through the experience of a young Haitian man with MDR TB, a disease never before described in Haiti. Insights from this case, and from other research on TB and HIV disease, are considered in the light of past anthropological writings on TB. It is argued that, often, social scientists mar contributions to an understanding of TB by making "immodest claims of causality" regarding its distribution and course. Alternative strategies for future sociomedical research on MDR TB are proposed.