Deleting IP6K1 stabilizes neuronal sodium-potassium pumps and suppresses excitability

Inositol pyrophosphates are key signaling molecules that regulate diverse neurobiological processes. We previously reported that the inositol pyrophosphate 5-InsP7, generated by inositol hexakisphosphate kinase 1 (IP6K1), governs the degradation of Na+/K+-ATPase (NKA) via an autoinhibitory domain of PI3K p85α. NKA is required for maintaining electrochemical gradients for proper neuronal firing. Here we characterized the electrophysiology of IP6K1 knockout (KO) neurons to further expand upon the functions of IP6K1-regulated control of NKA stability. We found that IP6K1 KO neurons have a lower frequency of action potentials and a specific deepening of the afterhyperpolarization phase. Our results demonstrate that deleting IP6K1 suppresses neuronal excitability, which is consistent with hyperpolarization due to an enrichment of NKA. Given that impaired NKA function contributes to the pathophysiology of various neurological diseases, including hyperexcitability in epilepsy, our findings may have therapeutic implications.

Depleting inositol pyrophosphate 5-InsP7 protected the heart against ischemia-reperfusion injury by elevating plasma adiponectin

AIMS

Adiponectin is an adipocyte-derived circulating protein that exerts cardiovascular and metabolic protection. Due to the futile degradation of endogenous adiponectin and the challenges of exogenous administration, regulatory mechanisms of adiponectin biosynthesis are of significant pharmacological interest.

METHODS AND RESULTS

Here, we report that 5-diphosphoinositol 1,2,3,4,6-pentakisphosphate (5-InsP7) generated by inositol hexakisphosphate kinase 1 (IP6K1) governed circulating adiponectin levels via thiol-mediated protein quality control in the secretory pathway. IP6K1 bound to adiponectin and DsbA-L and generated 5-InsP7 to stabilize adiponectin/ERp44 and DsbA-L/Ero1-Lα interactions, driving adiponectin intracellular degradation. Depleting 5-InsP7 by either IP6K1 deletion or pharmacological inhibition blocked intracellular adiponectin degradation. Whole-body and adipocyte-specific deletion of IP6K1 boosted plasma adiponectin levels, especially its high molecular weight forms, and activated AMPK-mediated protection against myocardial ischemia-reperfusion injury. Pharmacological inhibition of 5-InsP7 biosynthesis in WT but not adiponectin knockout mice attenuated myocardial ischemia-reperfusion injury.

CONCLUSIONS

Our findings revealed that 5-InsP7 is a physiological regulator of adiponectin biosynthesis that is amenable to pharmacological intervention for cardioprotection.

Itraconazole inhibits endothelial cell migration by disrupting inositol pyrophosphate-dependent focal adhesion dynamics and cytoskeletal remodeling

The antifungal drug itraconazole has been repurposed to anti-angiogenic agent, but the mechanisms of action have been elusive. Here we report that itraconazole disrupts focal adhesion dynamics and cytoskeletal remodeling, which requires 5-diphosphoinositol 1,2,3,4,6-pentakisphosphate (5-InsP₇). We find that inositol hexakisphosphate kinase 1 (IP6K1) binds Arp2 and generates 5-InsP₇ to recruit coronin, a negative regulator of the Arp2/3 complex. IP6K1 also produces focal adhesion-enriched 5-InsP₇, which binds focal adhesion kinase (FAK) at the FERM domain to promote its dimerization and phosphorylation. Itraconazole treatment elicits displacement of IP6K1/5-InsP₇, thus augments 5-InsP₇-mediated inhibition of Arp2/3 complex and reduces 5-InsP₇-mediated FAK dimerization. Itraconazole-treated cells display reduced focal adhesion dynamics and actin cytoskeleton remodeling. Accordingly, itraconazole severely disrupts cell motility, an essential component of angiogenesis. These results demonstrate critical roles of IP6K1-generated 5-InsP₇ in regulating focal adhesion dynamics and actin cytoskeleton remodeling and reveal functional mechanisms by which itraconazole inhibits cell motility.

Structural biology and thermodynamics of GluD receptors

Glutamate delta (GluD) receptors are a functionally enigmatic subfamily of ionotropic glutamate receptors. Despite sharing similar sequences and structures with AMPA, NMDA, and kainate receptors, GluD receptors do not bind glutamate nor function as ligand-gated ion channels. Binding d-serine and engaging in transsynaptic protein-protein interactions, GluD receptors are thought to undergo complex conformational rearrangements for non-ionotropic signaling that regulates synaptic plasticity. Recent structural, biochemical, and computational studies have elucidated multiple conformational and thermodynamic factors governing the unique properties of GluD receptors. Here, we review advances in biophysical insights into GluD receptors and discuss the structural thermodynamic relationships that underpin their neurobiological functions.

Self-reported health without clinically measurable benefits among adult users of multivitamin and multimineral supplements: a cross-sectional study

OBJECTIVE

Multiple clinical trials fail to identify clinically measurable health benefits of daily multivitamin and multimineral (MVM) consumption in the general adult population. Understanding the determinants of widespread use of MVMs may guide efforts to better educate the public about effective nutritional practices. The objective of this study was to compare self-reported and clinically measurable health outcomes among MVM users and non-users in a large, nationally representative adult civilian non-institutionalised population in the USA surveyed on the use of complementary health practices.

DESIGN

Cross-sectional analysis of the effect of MVM consumption on self-reported overall health and clinically measurable health outcomes.

PARTICIPANTS

Adult MVM users and non-users from the 2012 National Health Interview Survey (n=21 603).

PRIMARY AND SECONDARY OUTCOME MEASURES

Five psychological, physical, and functional health outcomes: (1) self-rated health status, (2) needing help with routine needs, (3) history of 10 chronic diseases, (4) presence of 19 health conditions in the past 12 months, and (5) Kessler 6-Item (K6) Psychological Distress Scale to measure non-specific psychological distress in the past month.

RESULTS

Among 4933 adult MVM users and 16 670 adult non-users, MVM users self-reported 30% better overall health than non-users (adjusted OR 1.31; 95% CI 1.17 to 1.46; false discovery rate adjusted p<0.001). There were no differences between MVM users and non-users in history of 10 chronic diseases, number of present health conditions, severity of current psychological distress on the K6 Scale and rates of needing help with daily activities. No effect modification was observed after stratification by sex, education, and race.

CONCLUSIONS

MVM users self-reported better overall health despite no apparent differences in clinically measurable health outcomes. These results suggest that widespread use of multivitamins in adults may be a result of individuals' positive expectation that multivitamin use leads to better health outcomes or a self-selection bias in which MVM users intrinsically harbour more positive views regarding their health.

The inositol pyrophosphate 5-InsP7 drives sodium-potassium pump degradation by relieving an autoinhibitory domain of PI3K p85α

Sodium/potassium-transporting adenosine triphosphatase (Na⁺/K⁺-ATPase) is one of the most abundant cell membrane proteins and is essential for eukaryotes. Endogenous negative regulators have long been postulated to play an important role in regulating the activity and stability of Na⁺/K⁺-ATPase, but characterization of these regulators has been elusive. Mechanisms of regulating Na⁺/K⁺-ATPase homeostatic turnover are unknown. Here, we report that 5-diphosphoinositol 1,2,3,4,6-pentakisphosphate (5-InsP₇), generated by inositol hexakisphosphate kinase 1 (IP6K1), promotes physiological endocytosis and downstream degradation of Na⁺/K⁺-ATPase-α1. Deletion of IP6K1 elicits a twofold enrichment of Na⁺/K⁺-ATPase-α1 in plasma membranes of multiple tissues and cell types. Using a suite of synthetic chemical biology tools, we found that 5-InsP₇ binds the RhoGAP domain of phosphatidylinositol 3-kinase (PI3K) p85α to disinhibit its interaction with Na⁺/K⁺-ATPase-α1. This recruits adaptor protein 2 (AP2) and triggers the clathrin-mediated endocytosis of Na⁺/K⁺-ATPase-α1. Our study identifies 5-InsP₇ as an endogenous negative regulator of Na⁺/K⁺-ATPase-α1.

D-Serine Potently Drives Ligand-Binding Domain Closure in the Ionotropic Glutamate Receptor GluD2

Despite their classification as ionotropic glutamate receptors, GluD receptors are not functional ligand-gated ion channels and do not bind glutamate. GluD2 receptors bind D-serine and coordinate transsynaptic complexes that regulate synaptic plasticity. Instead of opening the ion channel pore, mechanical tension produced from closure of GluD2 ligand-binding domains (LBDs) drives conformational rearrangements for non-ionotropic signaling. We report computed conformational free energy landscapes for the GluD2 LBD in apo and D-serine-bound states. Unexpectedly, the conformational free energy associated with GluD2 LBD closure upon D-serine binding is greater than that for AMPA, NMDA, and kainate receptor LBDs upon agonist binding. This excludes insufficient force generation as an explanation for lack of ion channel activity in GluD2 receptors and suggests that non-ionotropic conformational rearrangements do more work than pore opening. We also report free energy landscapes for GluD2 LBD harboring a neurodegenerative mutation and demonstrate selective stabilization of closed conformations in the apo state.

Preliminary dengue vector surveillance in the Sunda Islands, Indonesia: Interchange of breeding habitat preferences of Aedes aegypti and Aedes albopictus

Ovitrap surveillance was conducted to determine the infestation patterns of dengue vectors in fourteen study sites across eight provinces located in the Sunda Islands, Indonesia. High ovitrap indices up to 70% and 90% were obtained from indoor and outdoor areas, respectively. Mean numbers of Ae. aegypti and Ae. albopictus larvae ranged from 0.13 to 14.50 and 0.10 to 18.60, respectively. Mixed infestation (<10%) and interchange of breeding habitat preferences of Ae. albopictus and Ae. aegypti were also observed in the present study.

Monitoring Insecticide Resistance Profiles of Aedes aegypti (Diptera: Culicidae) in the Sunda Islands of Indonesia Based on Diagnostic Doses of Larvicides

This study was conducted to monitor the susceptibility status of Aedes aegypti (Linnaeus) larvae in the Sunda Islands of Indonesia against various organophosphates and organochlorines. Larval bioassay was performed in accordance with the World Health Organization standard protocol. Field-collected and reference strains of Ae. aegypti larvae were tested against diagnostic doses of eight larvicides belonging to organophosphates and organochlorines, namely bromophos (0.050 mg/liter), chlopyrifos (0.002 mg/liter), fenitrothion (0.020 mg/liter), fenthion (0.025 mg/liter), malathion (0.125 mg/liter), temephos (0.012 mg/liter), DDT (0.012 mg/liter), and dieldrin (0.025 mg/liter). Mortality rates of larvae were recorded at 24-h posttreatment. This study showed that Ae. aegypti larvae from Padang, Samarinda, Manggarai Barat, and South Central Timor were susceptible to both fenitrothion and dieldrin (mortality rates ≥ 98%). About 6 out of 10 field strains of Ae. aegypti larvae were resistant (<80% mortality rates) against fenthion, whereas Ae. aegypti larvae from Kuningan, Samarinda, Sumba, and South Central Timor exhibited some degrees of resistance (mortality rates 80-98%). All field-collected Ae. aegypti larvae were resistant against diagnostic doses of chlorpyrifos, malathion, temephos, and DDT with mortality rates ranging from 0 to 74.67%. Continued insecticide susceptibility studies are essential to identify the efficacy of insecticides for an improved dengue vector control and to delay the development of insecticide resistance.

Neuroinflammation and the cGAS-STING pathway

The recent discovery of cyclic GMP-AMP synthase (cGAS) as the mammalian cytosolic DNA sensor has profound therapeutic implications for infection, immunology, and cancer. Because neurovirology, neuroimmunology, neuro-oncology, and neurodegeneration implicate cytosolic DNA sensing, cGAS activation and induction of the downstream signaling protein stimulator of interferon genes (STING) has become increasingly recognized as a crucial determinant of neuropathophysiology. This Neuro Forum article reviews recent advances on the role of cGAS-STING signaling in neuroinflammation and neurological disease.

High Conformational Variability in the GluK2 Kainate Receptor Ligand-Binding Domain

The kainate family of ionotropic glutamate receptors (iGluRs) mediates pre- and postsynaptic neurotransmission. Previously computed conformational potentials of mean force (PMFs) for iGluR ligand-binding domains (LBDs) revealed subtype-dependent conformational differences between α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartic acid (NMDA) iGluR subfamilies. Here we report PMFs for the kainate receptor GluK2 in apo and glutamate-bound states. Apo and glutamate-bound GluK2 LBDs preferentially access closed-cleft conformations. Apo GluK2 exhibits a surprisingly high degree of conformational flexibility, accessing open and closed states. Comparing across iGluR subtypes, these results are similar to glycine-binding GluN1 and GluN3A NMDA subunits and differ from glutamate-binding GluA2 and GluN2A subunits. To test the contribution of cross-lobe interactions on closed-cleft LBD stability, we computed PMFs for two GluK2 mutants, D462A and D656S. D462A, but not D656S, weakens closed-cleft conformations of the glutamate-bound LBD. Theoretical Boltzmann-weighted small-angle X-ray scattering profiles improve agreement with experimental results compared with calculations from the LBD crystal structure alone.

Bioefficacy Evaluation of Commercial Mosquito Coils Containing Metofluthrin, d-Allethrin, d-Trans Allethrin, and Prallethrin Against Aedes albopictus (Diptera: Culicidae) in Malaysia

The bioefficacy of commercial mosquito coils containing four different active ingredients, namely metofluthrin, d-allethrin, d-trans allethrin, and prallethrin against Aedes albopictus (Skuse) (Diptera: Culicidae) from 10 states in Malaysia, was evaluated using the glass chamber method. In this study, Ae. albopictus exhibited various knockdown rates (50% knockdown time, KT50), ranging from 2.50 to 5.00 min, 2.50 to 7.00 min, 3.00 to 8.00 min, and 5.00 to 17.00 min for metofluthrin, d-trans allethrin, d-allethrin, and prallethrin, respectively. Overall, all strains of Ae. albopictus were most susceptible to metofluthrin, with mortality rates >80%. On the other hand, mortality rates ranging from 5.0 to 100% were observed from all populations exposed to d-trans allethrin, d-allethrin, and prallethrin. In addition, significant correlations between KT50 of metofluthrin and d-allethrin (r = 0.758, P = 0.011), metofluthrin and prallethrin (r = 0.676, P = 0.032), d-allethrin and d-trans allethrin (r = 0.832, P = 0.003), d-allethrin and prallethrin (r = 0.921, P = 0.000), and d-trans allethrin with prallethrin (r = 0.941, P = 0.000) were detected, suggesting some levels of cross-resistance within the pyrethroid insecticides. This study demonstrated that metofluthrin can induce high insecticidal activity in Ae. albopictus in Malaysia, followed by d-trans allethrin, d-allethrin, and prallethrin.

Multiple aspects of male germ cell development and interactions with Sertoli cells require inositol hexakisphosphate kinase-1

Inositol hexakisphosphate kinase-1 (IP6K1) is required for male fertility, but the underlying mechanisms have been elusive. Here, we report that IP6K1 is required for multiple aspects of male germ cell development. This development requires selective interactions between germ cells and Sertoli cells, namely apical ectoplasmic specialization. Spermiation (sperm release) requires tubulobulbar complexes. We found that the apical ectoplasmic specialization and tubulobulbar complexes were poorly formed or disrupted in IP6K1 KOs. Deletion of IP6K1 elicited several aberrations, including: 1, sloughing off of round germ cells; 2, disorientation and malformation of elongating/elongated spermatids; 3, degeneration of acrosomes; 4, defects in germ-Sertoli cell interactions and 5, failure of spermiation. Eventually the sperm cells were not released but phagocytosed by Sertoli cells leading to an absence of sperm in the epididymis.

Inositol Polyphosphate Multikinase Inhibits Angiogenesis via Inositol Pentakisphosphate-Induced HIF-1α Degradation

RATIONALE

Inositol polyphosphate multikinase (IPMK) and its major product inositol pentakisphosphate (IP5) regulate a variety of cellular functions, but their role in vascular biology remains unexplored.

OBJECTIVE

We have investigated the role of IPMK in regulating angiogenesis.

METHODS AND RESULTS

Deletion of IPMK in fibroblasts induces angiogenesis in both in vitro and in vivo models. IPMK deletion elicits a substantial increase of VEGF (vascular endothelial growth factor), which mediates the regulation of angiogenesis by IPMK. The regulation of VEGF by IPMK requires its catalytic activity. IPMK is predominantly nuclear and regulates gene transcription. However, IPMK does not apparently serve as a transcription factor for VEGF. HIF (hypoxia-inducible factor)-1α is a major determinant of angiogenesis and induces VEGF transcription. IPMK deletion elicits a major enrichment of HIF-1α protein and thus VEGF. HIF-1α is constitutively ubiquitinated by pVHL (von Hippel-Lindau protein) followed by proteasomal degradation under normal conditions. However, HIF-1α is not recognized and ubiquitinated by pVHL in IPMK KO (knockout) cells. IP5 reinstates the interaction of HIF-1α and pVHL. HIF-1α prolyl hydroxylation, which is prerequisite for pVHL recognition, is interrupted in IPMK-deleted cells. IP5 promotes HIF-1α prolyl hydroxylation and thus pVHL-dependent degradation of HIF-1α. Deletion of IPMK in mouse brain increases HIF-1α/VEGF levels and vascularization. The increased VEGF in IPMK KO disrupts blood-brain barrier and enhances brain blood vessel permeability.

CONCLUSIONS

IPMK, via its product IP5, negatively regulates angiogenesis by inhibiting VEGF expression. IP5 acts by enhancing HIF-1α hydroxylation and thus pVHL-dependent degradation of HIF-1α.

Comparative Efficacy of Commercial Mosquito Coils Against Aedes aegypti (Diptera: Culicidae) in Malaysia: A Nationwide Report

This study was conducted using the glass chamber method to determine the susceptibility status of the dengue vector, Aedes aegypti (L.) from 11 states in Malaysia to commercial mosquito coils containing four different active ingredients, namely metofluthrin, d-allethrin, d-trans allethrin, and prallethrin. Aedes aegypti exhibited various knockdown rates, ranging from 14.44% to 100.00%, 0.00% to 61.67%, 0.00% to 90.00%, and 0.00% to 13.33% for metofluthrin, d-allethrin, d-trans allethrin, and prallethrin, respectively. Overall, mortality rates ranging from 0.00% to 78.33% were also observed among all populations. Additionally, significant associations were detected between the knockdown rates of metofluthrin and d-allethrin, and between metofluthrin and d-trans allethrin, suggesting the occurrence of cross-resistance within pyrethroid insecticides. Overall, this study revealed low insecticidal activity of mosquito coils against Ae. aegypti populations in Malaysia, and consequently may provide minimal personal protection against mosquito bites.

Giant hepatic adenoma with atypical features in a patient on oxcarbazepine therapy

An association between oxcarbazepine therapy and hepatic adenoma (HA) has been documented in animal models but not observed in humans. The authors report a case of a 16-year-old girl on oxcarbazepine therapy for seizure disorder who presented with a giant HA. Pathology of the HA was notable for marked periductal fibrosis and glycoprotein inclusions in the nontumor liver. The patient was not on oral contraceptives and has no other known risk factors for HA.

Large scrotal hernia: a complicated case of mesh migration, ascites, and bowel strangulation

A 30-year-old male with 1 1/2-year history of an asymptomatic, large, reducible right indirect scrotal hernia presented to the emergency department complaining of a 2-week history of increasing abdominal distension and daily emesis. He had recently undergone an emergent exploratory laparotomy in which his asymptomatic hernia was repaired with a mesh plug from an intra-abdominal approach. The mesh plug subsequently migrated into the patient's scrotum resulting in a strangulating bowel obstruction. This paper discusses a serious complication that may result from inappropriate use and placement of a mesh plug and our approach to correct the situation utilizing a bioabsorbable mesh prosthesis.

Paraneoplastic pemphigus and bronchiolitis obliterans associated with a mediastinal mass: A rare case of Castleman's disease with respiratory failure requiring lung transplantation

Castleman's disease is an infrequent and usually benign lymphoproliferative disorder. Resection of the tumor usually is curative. The immunostimulatory nature of the tumor can, in rare instances, result in paraneoplastic manifestations. The authors present a case of a 14 year old with mucocutaneous ulcerations and progressive dyspnea that was found to have a large mediastinal mass and circulating autoantibodies that were responsible for his paraneoplastic pemphigus and bronchiolitis obliterans. In spite of aggressive immunotherapy to control the autoimmune mucocutaneous lesions, the pulmonary fibrosis was irreversible and progressed to pulmonary failure necessitating lung transplantation. J Pediatr Surg 36:E22.

Tilmicosin induces apoptosis in bovine peripheral neutrophils in the presence or in the absence of Pasteurella haemolytica and promotes neutrophil phagocytosis by macrophages

Pathogen virulence factors and inflammation are responsible for tissue injury associated with respiratory failure in bacterial pneumonia, as seen in the bovine lung infected with Pasteurella haemolytica. Tilmicosin is a macrolide antibiotic used for the treatment of bovine bacterial pneumonia. Recent evidence suggests that tilmicosin-induced neutrophil apoptosis may have anti-inflammatory effects. Using bovine leukocytes, we sought to define whether live P. haemolytica affected tilmicosin-induced neutrophil apoptosis, assessed the proapoptotic effects of tilmicosin in comparison with other drugs, and characterized its impact on phagocytic uptake of neutrophils by macrophages. Induction of apoptosis in the presence or absence of P. haemolytica was assessed by using an enzyme-linked immunosorbent assay for apoptotic nucleosomes. In addition, fluorescent annexin-V staining identified externalized phosphatidylserine in neutrophils treated with tilmicosin, penicillin, ceftiofur, oxytetracycline, or dexamethasone. Neutrophil membrane integrity was assessed by using propidium iodide and trypan blue exclusion. As phagocytic clearance of apoptotic neutrophils by macrophages contributes to the resolution of inflammation, phagocytosis of tilmicosin-treated neutrophils by esterase-positive cultured bovine macrophages was assessed with light microscopy and transmission electron microscopy. Unlike bovine neutrophils treated with penicillin, ceftiofur, oxytetracycline, or dexamethasone, neutrophils exposed to tilmicosin became apoptotic, regardless of the presence or absence of P. haemolytica. Tilmicosin-treated apoptotic neutrophils were phagocytosed at a significantly greater rate by bovine macrophages than were control neutrophils. In conclusion, tilmicosin-induced neutrophil apoptosis occurs regardless of the presence or absence of live P. haemolytica, exhibits at least some degree of drug specificity, and promotes phagocytic clearance of the dying inflammatory cells.

Congenital cysts of the third and fourth pharyngeal pouches or pyriform sinus cysts

Cysts arising from the III and IV pharyngeal pouches, although uncommon, are typical in their presentation. They occur in neonates, invariably in the left anterior neck and cause respiratory distress. Excision of the cyst with ligation of the tract at the level of the pyriform sinus is curative.

Apoptosis, oxidative metabolism and interleukin-8 production in human neutrophils exposed to azithromycin: effects of Streptococcus pneumoniae

Pathogen virulence factors and the host inflammatory response cause tissue injury associated with respiratory tract infections. The azalide azithromycin has demonstrated efficacy in the treatment of these infections. It has been demonstrated previously that induction of polymorphonuclear leucocyte (PMN) apoptosis is associated with minimization of tissue damage and inflammation in the lung. We hypothesized that, in addition to its antibacterial effects, azithromycin may promote apoptosis. The aim of the study was to determine the effects of azithromycin on PMN apoptosis, oxidative function and interleukin-8 (IL-8) production in the presence or absence of Streptococcus pneumoniae, in comparison with penicillin, erythromycin, dexamethasone or phosphate-buffered saline. Human circulating PMNs were assessed for apoptosis (by annexin V labelling and ELISA), oxidative function (by nitroblue tetrazolium reduction) and IL-8 production (by ELISA). Azithromycin significantly induced PMN apoptosis in the absence of S. pneumoniae after 1 h (10.27% +/- 1.48%, compared with 2.19% +/- 0.42% in controls) to levels similar to those after 3 h induction with tumour necrosis factor-alpha (8. 73% +/- 1.86%). This effect was abolished in the presence of S. pneumoniae. Apoptosis in PMNs exposed to the other drugs was not significantly different from that in controls. Azithromycin did not affect PMN oxidative metabolism or IL-8 production. In summary, azithromycin-induced PMN apoptosis may be detected in the absence of any effect on PMN function, and the pro-apoptotic properties of azithromycin are inhibited in the presence of S. pneumoniae.

Anti-inflammatory benefits of tilmicosin in calves with Pasteurella haemolytica-infected lungs

OBJECTIVES

To determine whether tilmicosin alters neutrophil infiltration or function, induces neutrophil apoptosis, and affects accumulation of leukotriene B4 (LTB4) or tumor necrosis factor-alpha (TNF-alpha) in lungs of calves experimentally infected with Pasteurella haemolytica.

ANIMALS

12 weight-ranked Holstein calves.

PROCEDURE

Calves were given 25% propylene glycol vehicle (n = 5) or tilmicosin (10 mg/kg of body weight; n = 6) subcutaneously, 18 hours and 15 minutes before intratracheal infection with 2 x 10(8) P haemolytica organisms. Two unmanipulated calves served as controls in some experiments. Rectal temperatures were recorded 15 minutes before, and at 3-hour intervals after infection for 24 hours. Samples obtained from bronchoalveolar lavage performed 3 and 24 hours after infection were used to assess colonization by P haemolytica, and neutrophil infiltration. Neutrophil phagocytosis of P haemolytica, membrane leakage as determined by trypan blue exclusion, oxidative function as determined by nitro blue tetrazolium reduction, and apoptosis, using electron microscopy and DNA fragmentation ELISA, were determined. SOluble TNF-alpha and LTB4 were measured from supernatants from bronchoalveolar lavage samples, using ELISA.

RESULTS

Treatment with tilmicosin resulted in significant (P < 0.05) clearance of P haemolytica and neutrophil apoptosis at 3 hours, and decreased concentration of LTB4 at 24 hours. Rectal temperatures, neutrophil infiltration, phagocytosis, oxidative functions, membrane leakage, and soluble TNF-alpha concentrations were not significantly affected by tilmicosin.

CONCLUSION

Tilmicosin effectively controlled P haemolytica infection, induced neutrophil apoptosis, reduced pulmonary inflammation, and did not affect neutrophil infiltration or function.

CLINICAL RELEVANCE

By inducing neutrophil apoptosis, tilmicosin prevents further amplification of inflammatory injury in P haemolytica-infected lungs.

Value of helical computed tomography, angiography, and endoscopic ultrasound in determining resectability of periampullary carcinoma

BACKGROUND

High-quality preoperative radiographic evaluation is crucial in selecting patients with periampullary carcinomas who are candidates for surgical exploration and tumor resection while minimizing the rate of unnecessary laparotomy.

METHODS

Twenty-one consecutive patients were prospectively investigated using helical computed tomography (CT) scanning, endoscopic ultrasonography (EUS), and selective visceral angiography (SVA) to determine tumor resectability. All patients were explored and resectability determined.

RESULTS

Helical CT had a sensitivity of 63%, a specificity of 100%, and an overall accuracy of 86%. EUS had a sensitivity of 75%, a specificity of 77%, and an overall accuracy of 76%. SVA had a sensitivity of 38%, a specificity of 92%, and an overall accuracy of 71%.

CONCLUSIONS

Helical CT scanning is the best preoperative imaging test to determine tumor resectability. EUS is more sensitive than CT for tumor detection, but underestimates resectability. SVA is no longer helpful in the preoperative evaluation of these malignancies.

Cloning and functional promoter mapping of the rat serotonin-2 receptor gene

We have cloned the gene encoding the rat serotonin-2 (5-HT2) receptor. The transcription unit is divided into three exons by two introns. The major 5-HT2 transcript is 5.62 kb in length and contains 1173 bases of 5'-untranslated region (5'-UTR) 1413 bases of open reading frame, and 3033 bases of 3'-UTR. Primer extension demonstrates one strong transcription initiation site 1173 nt from the start codon. Reverse transcriptase-polymerase chain reaction analysis indicates the presence of at least one additional minor site of transcription initiation 1355 nt from the start codon. There are ATA boxes 28 nt 5' to both the major and minor sites of transcription initiation. Functional promoter mapping was carried out in a transient transfection assay. This analysis reveals that there are negative attenuating elements between 2.5 and 2.3 kb from the initiation site and positive elements between 1100 and 200 nt from transcription initiation. Minimal promoter sequences are contained within 200 nt of the major site of transcription initiation. These findings suggest that the expression of the 5-HT2 receptor gene is regulated by a combination of positive and negative elements operating through the minimal promoter.

Identification and characterization of Drosophila genes for synaptic vesicle proteins

Proteins associated with synaptic vesicles are likely to control the release of neurotransmitter. Because synaptic transmission is fundamentally similar between vertebrates and invertebrates, vesicle proteins from vertebrates that are important for synaptic transmission should be present in Drosophila as well. This investigation describes Drosophila homologs of vamp, synaptotagmin, and rab3 that are expressed in a pattern consistent with a function in Drosophila neurotransmission. One previously reported candidate (syb), a Drosophila homolog of the vamp or synaptobrevin proteins, has been shown to be expressed at very low levels in neurons and is most abundant in the gut. A neuronal Drosophila vamp (n-syb) is described here and is localized to chromosome band 62A. Northern analysis and in situ hybridizations to mRNA indicate that the novel vamp, as well as the genes for synaptotagmin (syt) and rab3 (drab3), is expressed in the Drosophila nervous system. These genes are widely (perhaps ubiquitously) expressed in the nervous system and we have no evidence of additional neuronal isoforms of synaptotagmin, vamp, or rab3. Immunoreactivity for synaptotagmin and vamp is located in synaptic regions of the nervous system. This distribution suggests that these molecules are components of synaptic vesicles in Drosophila. The conserved structure and neuronal expression pattern of these genes indicate that they may function in processes that are required for both vertebrate and invertebrate synaptic transmission. Because of their distribution in the nervous system and because n-syb, synaptotagmin, and drab3 do not appear to be in a family of functionally redundant homologs, we predict that mutation of these genes will have a profound neurological phenotype and that they are therefore good candidates for a genetic dissection in Drosophila.

Differential expression of transcripts from syb, a Drosophila melanogaster gene encoding VAMP (synaptobrevin) that is abundant in non-neuronal cells

VAMP (synaptobrevin) is a highly conserved membrane protein originally described as a component of brain synaptic vesicles. The Drosophila melanogaster VAMP-encoding gene (syb) comprises five exons. Splicing exons 1,2,3,4,5 (syb-b) results in a protein with a C-terminal hydrophobic domain and a negligible intraluminal domain. Splicing exons 1,2,3,5 (syb-a) predicts a protein with a 20-amino-acid luminal domain at the C terminus. The ratio of syb-a to syb-b transcripts is highly regulated during development. The syb transcripts show no enrichment in the nervous system and are present in very early embryos, well before neurogenesis. The greatest concentration of syb transcripts was found in cells of the gut and malpighian tubules. Thus, syb may have a general role in membrane trafficking and, perhaps, a role in the secretion of digestive enzymes.

Recombinant porin of Haemophilus influenzae type b

A protein of approximately 40 kDa in the outer membrane of Haemophilus influenzae type b (Hib) behaves as a porin and permits transmembrane diffusion of low-molecular-weight solutes. The gene for Hib porin was cloned from an M13 library of chromosomal DNA of Hib strain ATCC9795. The gene was subcloned into a new transfer vector as a prerequisite for its use in the baculovirus expression vector system. Pure recombinant virus (AcPORIN) was isolated. On infection of a cultivated insect cell line Sf9 with AcPORIN, a novel protein was detected in cell lysates, and this novel protein reacted with an anti-Hib porin monoclonal antibody. The purified recombinant Hib porin was tested for its pore-forming properties in a synthetic black lipid membrane. The biophysical activity of purified recombinant Hib porin was identical to porin isolated from the bacterial outer membrane.

Monoclonal antibodies specific to porin of Haemophilus influenzae type b: localization of their cognate epitopes and tests of their biological activities

The major outer membrane protein of Haemophilus influenzae type b (Hib) is porin (Mr 38,000, 341 amino acids). To identify antigenic determinants on Hib porin that might be exposed at the bacterial cell surface, seven mouse monoclonal anti-Hib porin antibodies were generated. The monoclonal antibodies were tested for their binding to intact cells by flow cytometry; all but one bound to the cell surface. Digestions of Hib porin with cyanogen bromide, hydroxylamine or trypsin generated fragments, the identities of which were confirmed by microsequencing of the amino termini. Following electrophoresis and immunoblotting of the fragments, the specificities of the monoclonal antibodies for their cognate sequences were determined. The porin gene ompP2 was expressed in the baculovirus expression vector system; the recombinant porin was recognized by all of the monoclonal antibodies. Deletions were created by omega mutagenesis of ompP2, generating proteins truncated after amino acids 139, 174, 182, and 264. These deletion proteins were tested for reactivities with the monoclonal antibodies, thereby establishing the boundaries of three antigenic determinants that were recognized by the monoclonals: domain (i), amino acids 104-139; domain (ii) amino acids 162-174; and domain (iii), amino acids 267-341. The biological activities of monoclonal antibodies that were representative of these three classes were tested for their bactericidal activity in complement-mediated lysis of whole cells. The monoclonal antibodies were also tested for their immunoprotective properties in the infant rat model of bacteraemia. Although the monoclonal antibodies were surface-binding, they were neither bactericidal nor protective.

Organization and expression of the Drosophila FMRFamide-related prohormone gene

The Drosophila FMRFamide gene is comprised of two exons separated by a 2.8-kb intervening sequence. The first exon consists of the 5' untranslated region and is spliced to the initiator methionine codon. The second exon encodes the prohormone and the 3' untranslated region of the mRNA. The promoter region contains a TATA box 30 nucleotides upstream from a consensus transcription start site. Immunohistochemical studies using antibodies generated against synthetic peptides and in situ hybridization histochemistry define a set of about 40 neurons in the brain and ventral ganglia that express the prohormone gene.

Tse-2: a trans-dominant extinguisher of albumin gene expression in hepatoma hybrid cells

Serum albumin gene expression is generally extinguished in hepatoma x fibroblast hybrids. To define the genetic basis of this phenomenon, we screened a panel of hepatoma hybrids retaining different fibroblast chromosomes for albumin production by immunofluorescence. We report that albumin extinction in these clones was strictly correlated with the retention of mouse chromosome 1. Furthermore, albumin was systematically reexpressed in chromosome 1 segregants. These data define a tissue-specific extinguisher locus (Tse-2) that affects albumin gene expression in trans. Two other liver genes, those encoding liver alcohol dehydrogenase and liv-10, were coordinately extinguished with albumin in monochromosomal hybrids that specifically retained mouse chromosome 1.

Coordinate regulation of two genes encoding gluconeogenic enzymes by the trans-dominant locus Tse-1

Tissue-specific extinguisher-1 (Tse-1) is a mouse genetic locus that can repress liver-specific tyrosine aminotransferase gene expression in trans. To search for other Tse-1-responsive genes, hepatoma microcell hybrids retaining mouse chromosome 11 or human chromosome 17, containing murine Tse-1 and human TSE1, respectively, were screened for expression of liver-specific mRNAs. While most liver gene activity was unaffected in such hybrids, phosphoenolpyruvate carboxykinase and tyrosine aminotransferase gene expression was coordinately repressed in these clones. Extinction of both genes was apparently mediated by a single genetic locus that resides on human chromosome 17.

A genetic analysis of extinction: trans-regulation of 16 liver-specific genes in hepatoma-fibroblast hybrid cells

Hybrid cells formed by fusing different cell types generally fail to express the tissue-specific products of either parent, a phenomenon termed extinction. We have investigated the generality of this effect by assaying hepatoma-fibroblast hybrids for expression of 16 different liver-specific mRNAs. Fourteen of the mRNAs failed to accumulate in karyotypically complete hybrid clones, and quantitative measurements indicated that steady-state mRNA levels were depressed by a factor of at least 500-1000. However, all 14 liver-specific mRNAs were reexpressed in the hybrids following fibroblast chromosome loss. These data indicate that expression of whole sets of tissue-specific genes is affected in trans in intertypic hybrids and suggest that negative regulation of heterologous functions may be common form of gene control.

Tissue-specific expression of hepatic functions. Genetic aspects

Intertypic hybrids formed by fusing dissimilar cell types generally fail to express the tissue-specific products of either parent, a phenomenon termed extinction. To explore the genetic basis and phenotypic complexity of this phenomenon, 15 liver-specific cDNA clones have been used as probes to assay expression of the corresponding mRNAs in a series of hepatoma x fibroblast hybrids retaining different fibroblast chromosomes. Thirteen of the 15 liver-specific mRNAs were extinguished in karyotypically complete hepatoma x fibroblast hybrids, but were reexpressed in hybrid segregants that had eliminated fibroblast chromosomes. In three cases analyzed in detail, extinction of a particular hepatic marker required the presence of a single, specific fibroblast chromosome. These data define and localize a set of discrete genetic loci, the Tse loci, that negatively regulate liver-specific gene expression in trans.