Citations

Biologically active 125 I-labeled bovine parathyroid hormone (prepared by electrolytic iodination) and its synthetic NH 2 -terminal (1-34) biologically active fragment bound rapidly and specifically to a purified plasma membrane preparation from bovine renal cortex. Binding of labeled intact hormone or labeled NH 2 -terminal (1-34) peptide was inhibited competitively by unlabeled (1-34) peptide in the same range of concentrations that activated renal cortical 3′:5′-adenylate cyclase (EC 4.6.1.1) in these membranes. The concentrations of synthetic (1-34) peptide for half-maximal inhibition of binding of labeled hormone as well as half-maximal activation of the enzyme were about 0.6 μM (2.5 μg/ml). Therefore it is likely that the binding activity studied represents a physiologically important renal receptor for parathyroid hormone. Biologically inactive (oxidized) forms of parathyroid hormone and (1-34) NH 2 -terminal peptide as well as calcitonin, glucagon, insulin, and epinephrine failed to competitively inhibit the binding of labeled (1-34) parathyroid hormone or activate adenylate cyclase in the renal cortical membrane preparation. Observations with the NH 2 -terminal (1-34) biologically active fragment of parathyroid hormone suggest that the COOH-terminal region of the molecule is not required for receptor binding.

Background— Atrioventricular (AV) nodal ablation for management of atrial fibrillation (AF) is irreversible and requires permanent pacemaker implantation. We hypothesized that as an alternative, implantation of autologous fibroblasts in the perinodal region would focally modify AV nodal conduction and that this modulation would be enhanced by pretreatment with transforming growth factor-β1 (TGF-β1), a stimulant of fibroblasts. Methods and Results— Skin biopsies were taken from 12 mongrel dogs, and derived fibroblasts were dissociated and grown in culture for 2 weeks. Multiple injections (0.25 mL) were made through an 8F NOGA catheter along the fast/slow AV nodal pathways as guided by an electroanatomic mapping system. Seven dogs received fibroblasts alone (1×10 6 cells/mL), 7 dogs received TGF-β1 (5 μg), 4 dogs received fibroblasts and TGF-β1 (1×10 6 cells/mL+5 μg), and 4 dogs received saline only. AV node function was assessed at baseline and after 4 weeks. Saline (80 mL) with assigned therapy (0.25 mL per injection) was injected into the peri-AV nodal region in each dog. At baseline, the AH interval (66±3 ms) and the average RR interval (331±17 ms) in pacing-induced AF were similar in each cohort. The increase in AH interval in normal sinus rhythm was longer after fibroblast (23±4 versus 5±5 ms; P =0.05) and fibroblast plus TGF-β1 (50±5 versus 5±5 ms; P <0.001) injections than with saline alone, with similar findings during high right atrium and distal coronary sinus pacing. The AH interval was not significantly increased after TGF-β1 injections. The AH interval was significantly longer after fibroblast plus TGF-β1 injections than with either therapy (TGF-β1 or fibroblasts) alone. The RR interval during AF was increased in dogs that received fibroblasts alone (110±36 versus −41±34 ms) and to a greater extent with the addition of TGF-β1 (294±108 versus −41±34 ms). No AV block was seen in any cohort at 4 weeks. Labeled fibroblasts that expressed vimentin were identified in all dogs that received cell injections at 4 weeks. Conclusions— AV nodal modification can be achieved with injected fibroblasts without the creation of AV block. The effect on AV node conduction is substantially enhanced by pretreatment of fibroblasts with TGF-β1. These data have therapeutic potential for the management of rapid ventricular rate during AF without pacemaker implantation.

Abstract OBJECTIVE AND IMPORTANCE: Magnetic resonance imaging (MRI) is the imaging modality of choice for brain tumors and other lesions of the central nervous system. However, this procedure is contraindicated in patients with orbital metallic foreign bodies. In such cases, the usual clinical strategy is to manage the patient without the benefit of MRI scans and, instead, to rely on less sensitive imaging modalities in particular computed tomographic scanning. CLINICAL PRESENTATION: Two patients, one with a posterior fossa mass and one with suspected central nervous system lymphoma, were seen at our institution. MRI scanning was recommended, but had been precluded in both patients by the presence of metal fragments in the orbit. INTERVENTION: In each case, the orbital foreign body was successfully localized and removed. Postprocedure computed tomographic scanning confirmed complete removal. MRI scanning was then performed without difficulty. The first patient underwent posterior fossa craniotomy and removal of the tumor, which proved to be a medulloblastoma. The second patient was found to have evidence of lymphoma in the cranial base and meninges and was treated with radiotherapy and systemic and intrathecal chemotherapy. MRI scanning provided superior diagnostic information and spared both patients the risks and discomfort of myelography and exposure to ionizing radiation from multiple computerized tomographic scans. CONCLUSION: Two patients with central nervous system tumors underwent removal of a metal fragment in the orbit for the specific purpose of facilitating MRI scans. This is a practical, straightforward concept, which should be considered when MRI scanning is needed for optimal patient management.

Abstract Background: Controversy exists over the association of estrogen and cardiovascular disease. Estrogen receptors (ERs) α and β are expressed in the endothelial cells and vascular smooth muscle cells (VSMCs) of many arteries, but the relative importance of ERα or ERβ in mediating the vascular response to estrogens is not well defined, particularly in humans. We have shown previously that postmenopausal women receiving hormone therapy (HT) had lower mean coronary artery calcium, plaque area, and calcium-to-plaque ratio compared with untreated women. In this study, we examined coronary artery ERα and ERβ expression in pre- and postmenopausal women as a function of plaque area, calcium area, calcium-to-plaque ratio, and estrogen status. Methods: Coronary arteries were obtained at autopsy from a total of 55 women: nine premenopausal women, 13 postmenopausal women on HT and 33 untreated postmenopausal women (non-HT). Coronary calcification was quantified by contact microradiography, and atherosclerotic plaque area was measured histologically. Coronary artery cross-sections were immunostained for ERα and ERβ, and the amount of receptors was estimated semiquantitatively in each arterial wall layer (intima, adventitia, and media). Double immunofluorescence was used to colocalize ERα and ERβ with smooth muscle actin, a marker of VSMCs. Results: ERβ and ERα were expressed in all artery wall layers, but most avidly in the media (P = 0.001), and colocalized with VSMCs. ERβ expression exceeded ERα expression in all wall layers (P &lt; 0.001) and was adjacent to areas of calcium deposition. ERβ expression in the intimal layer correlated with calcium content, plaque area, and calcium-to-plaque ratio (all P &lt; 0.01) and tended to be greater in non-HT than in HT women (P = 0.06). ERα expression did not vary significantly among groups, nor did it correlate with calcium content, plaque area or calcium-to-plaque ratio. Expression of ERα but not ERβ declined with age (P &lt; 0.01) in HT women only. Age had no effect on ERα or ERβ expression in non-HT or premenopausal women. Conclusions: ERβ is the predominant ER in human coronary arteries and correlates with coronary calcification, a marker of severe atherosclerosis. Increased ERβ expression is linked to advanced atherosclerosis and calcification independent of age or hormone status. Future pharmacogenetic studies that target this receptor are needed to confirm causality.

Abstract Aberrant patterns of pre-mRNA splicing have been established for many human malignancies, yet the mechanisms responsible for these tumor-specific changes remain undefined and represent a promising area for therapeutic intervention. Using immunohistochemistry, we have localized the expression of a central splicing regulator, serine-arginine protein kinase 1 (SRPK1), to the ductular epithelial cells within human pancreas and have further shown its increased expression in tumors of the pancreas, breast, and colon. Small interfering RNA–mediated down-regulation of SRPK1 in pancreatic tumor cell lines resulted in a dose-dependent decrease in proliferative capacity and increase in apoptotic potential. Coordinately, the disruption of SRPK1 expression resulted in enhanced sensitivity of tumor cells to killing by gemcitabine and/or cisplatin. A dose-dependent reduction in the phosphorylation status of specific SR proteins was detected following the down-regulation of SRPK1 and is likely responsible for the observed alterations in expression of proteins associated with apoptosis and multidrug resistance. These data support SRPK1 as a new, potential target for the treatment of pancreatic ductular cancer that at present remains largely unresponsive to conventional therapies. Furthermore, these results support the development of innovative therapies that target not only specific splice variants arising during tumorigenesis but also the splice regulatory machinery that itself may be abnormal in malignant cells. (Cancer Res 2006; 66(7): 3819-27)

Abstract Intervention trials with supplemental β-carotene have observed either no effect or a harmful effect on lung cancer risk. Because food composition databases for specific carotenoids have only become available recently, epidemiological evidence relating usual dietary levels of these carotenoids with lung cancer risk is limited. We analyzed the association between lung cancer risk and intakes of specific carotenoids using the primary data from seven cohort studies in North America and Europe. Carotenoid intakes were estimated from dietary questionnaires administered at baseline in each study. We calculated study-specific multivariate relative risks (RRs) and combined these using a random-effects model. The multivariate models included smoking history and other potential risk factors. During follow-up of up to 7–16 years across studies, 3,155 incident lung cancer cases were diagnosed among 399,765 participants. β-Carotene intake was not associated with lung cancer risk (pooled multivariate RR = 0.98; 95% confidence interval, 0.87–1.11; highest versus lowest quintile). The RRs for α-carotene, lutein/zeaxanthin, and lycopene were also close to unity. β-Cryptoxanthin intake was inversely associated with lung cancer risk (RR = 0.76; 95% confidence interval, 0.67–0.86; highest versus lowest quintile). These results did not change after adjustment for intakes of vitamin C (with or without supplements), folate (with or without supplements), and other carotenoids and multivitamin use. The associations generally were similar among never, past, or current smokers and by histological type. Although smoking is the strongest risk factor for lung cancer, greater intake of foods high in β-cryptoxanthin, such as citrus fruit, may modestly lower the risk.

AbstractUnderstanding of the conformational changes in G protein-coupled receptors associated with activation and inactivation is of great interest. We previously used photoaffinity labeling to elucidate spatial approximations between photolabile residues situated throughout the pharmacophore of secretin agonist probes and this receptor. The aim of the current work was to develop analogous photolabile secretin antagonist probes and to explore their spatial approximations. The most potent secretin antagonist reported is a pseudopeptide ([ψ4, 5]secretin) in which the peptide bond between residues 4 and 5 was replaced by a ψ(CH2-NH) peptide bond isostere. We have developed a series of [ψ4, 5]secretin analogs incorporating photolabile benzoyl phenylalanine residues in positions 6, 22, and 26. Each bound to the secretin receptor saturably and specifically, with affinity similar to their parental peptide. At concentrations with no measurable agonist activity, each probe covalently labeled the secretin receptor. Peptide mapping using proteolytic cleavage, immunoprecipitation, and radiochemical sequencing identified that each of these three probes labeled the amino terminus of the secretin receptor. Whereas the position 22 probe labeled the same residue as its analogous agonist probe and the position 6 probe labeled a residue within two residues of that labeled by its analogous agonist probe, the position 26 probe labeled a site 16 residues away from that labeled by its analogous agonist probe. Thus, whereas structurally related agonist and antagonist probes dock in the same general region of this receptor, conformational differences in active and inactive states result in substantial differences in spatial approximation at the carboxyl-terminal end of secretin analogs.