bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvements in the Signal-to-Noise Ratio of Motor Cortex Cells Distinguish Early versus Late Phases of Motor Skill Learning
Authors: Kargo William J. , Nitz Douglas A.
Published: June 2004

There are numerous experience-driven changes in cortical circuitry that correlate with improved performance. Improved motor performance on a reach-to-grasp task in rodents is associated with changes in long-term potentiation (LTP), synaptogenesis, and movement representations in primary motor cortex (M1) by training days 3, 7, and 10, respectively. We recorded single-cell activity patterns in M1 during reach-to-grasp training to test how neural-spiking properties change with respect to LTP, synaptogenesis, and motor map changes. We also tested how neural-spiking changes relate directly to improved performance by monitoring muscle activity patterns. We found that signal-to-noise ratios (SNRs) of M1 spiking were significantly improved with practice but only after 7-12 d. Three sources of noise were assessed: signal-dependent noise exemplified by the slope of the relationship between mean spike count and count variance per burst, signal-independent noise exemplified by the offset of this relationship, and background firing rates before and after bursts. Signal-independent noise and pre-burst firing rates were reduced with practice. Early performance gains (days 1-6) were dissociated from SNR improvements, whereas later performance gains (day 7-12) were related directly to the magnitude of improvement in both muscle recruitment reliability and success rates. With training, an increased number of cells exhibited firing rates that were correlated with muscle recruitment patterns, with lags suggesting a primary direction of influence from M1 to muscles. These results suggest a functional linkage from local synaptogenesis in M1 to improved spiking reliability of M1 cells to more reliable recruitment of muscles and finally to improved behavioral performance.
Histone Modifications at Gene Promoter Regions in Rat Hippocampus after Acute and Chronic Electroconvulsive Seizures
Authors: Tsankova Nadia M. , Kumar Arvind , Nestler Eric J.
Published: June 2004

The mechanism of action of electroconvulsive seizures (ECS), one of the most effective treatments of major depression, may involve the regulation of gene expression. Chromatin remodeling at gene promoter regions is increasingly recognized as a key control point of gene expression and may, therefore, partly mediate acute and chronic effects of ECS on gene activity. Here, we assayed how posttranslational modifications of histones, a major form of chromatin remodeling, are altered at several gene promoters in rat hippocampus at 30 min, 2 hr, and 24 hr after acute or repeated ECS. We performed chromatin immunoprecipitation assays to measure levels of histone H3 and H4 acetylation and phosphoacetylation at the promoters of the c-fos, BDNF, andCREB(cAMP response element-binding protein) genes, the expression of which is altered by ECS. We found that, with few exceptions, levels of H4 acetylation correlated with mRNA levels for c-fos,BDNF, andCREBthroughout the acute and chronic time course study, whereas acetylation and phosphoacetylation of H3 were detected more selectively. Our findings suggest that the chronic downregulation of c-fostranscription, observed in this study, may be achieved at the level of H4 acetylation, whereas chronic upregulation ofBDNFtranscription may be sustained via control of H3 acetylation, selectively at theBDNF P3andP4promoters. These data provide the firstin vivodemonstration of the involvement of chromatin remodeling in ECS-induced regulation of gene expression in the brain and will help in understanding the mechanisms underlying the efficacy of ECS in the treatment of depression.
Acetylcholine Receptors Direct Rapsyn Clusters to the Neuromuscular Synapse in Zebrafish
Authors: Ono Fumihito , Mandel Gail , Brehm Paul
Published: June 2004

Clustering of nicotinic muscle acetylcholine receptors (AChRs) requires association with intracellular rapsyn, a protein with an intrinsic ability to self-cluster. Previous studies onsofa potato(sop), an AChR null line of zebrafish, have suggested that AChRs may play an active role in subsynaptic localization of rapsyn clusters. To test this proposal directly, we identified and cloned the gene responsible for thesopphenotype and then attempted to rescue subsynaptic localization of the receptor-rapsyn complex in mutant fish.sopcontains a leucine to proline mutation at position 28, near the N terminus of the zebrafish AChR δ subunit. Transient expression of mutant δ subunit insopfish was unable to restore surface expression of muscle AChRs. In contrast, expression of wild-type δ subunit restored the ability of muscle to assemble surface receptors along with the ability of fish to swim. Most importantly, the ability of rapsyn clusters to localize effectively to subsynaptic sites also was rescued in large part. Our results point to direct involvement of the AChR molecule in restricting receptor-rapsyn clusters to the synapse.
Endocannabinoids Inhibit Transmission at Granule Cell to Purkinje Cell Synapses by Modulating Three Types of Presynaptic Calcium Channels
Authors: Brown Solange P. , Safo Patrick K. , Regehr Wade G.
Published: June 2004

At many central synapses, endocannabinoids released by postsynaptic cells inhibit neurotransmitter release by activating presynaptic cannabinoid receptors. The mechanisms underlying this important means of synaptic regulation are not fully understood. It has been shown at several synapses that endocannabinoids inhibit neurotransmitter release by reducing calcium influx into presynaptic terminals. One hypothesis maintains that endocannabinoids indirectly reduce calcium influx by modulating potassium channels and narrowing the presynaptic action potential. An alternative hypothesis is that endocannabinoids directly and selectively inhibit N-type calcium channels in presynaptic terminals. Here we test these hypotheses at the granule cell to Purkinje cell synapse in cerebellar brain slices. By monitoring optically the presynaptic calcium influx (Cainflux) and measuring the EPSC amplitudes, we found that cannabinoid-mediated inhibition arises solely from reduced presynaptic Cainflux. Next we found that cannabinoid receptor activation does not affect the time course of presynaptic calcium entry, indicating that the reduced Cainfluxreflects inhibition of presynaptic calcium channels. Finally, we assessed the classes of presynaptic calcium channels inhibited by cannabinoid receptor activation via peptide calcium channel antagonists. Previous studies established that N-type, P/Q-type, and R-type calcium channels are all present in granule cell presynaptic boutons. We found that cannabinoid activation reduced Cainfluxthrough N-type, P/Q-type, and R-type calcium channels to 29, 60, and 55% of control, respectively. Thus, rather than narrowing the presynaptic action potential or exclusively modulating N-type calcium channels, CB1 receptor activation inhibits synaptic transmission by modulating all classes of calcium channels present in the presynaptic terminal of the granule cell to Purkinje cell synapse.
Paradoxical Potentiation of Neuronal T-Type Ca2+Current by ATP at Resting Membrane Potential
Authors: Leresche Nathalie , Hering Julien , Lambert Régis C.
Published: June 2004

Despite the marked influence on neuronal physiology of the low-voltage activated T-type Ca2+currents, little is known about the intracellular pathways and neurotransmitters involved in their regulations. Here, we report that in thalamocortical neurons a phosphorylation mechanism induces an increase both in the current amplitude (1.5 ± 0.27-fold in the ventrobasal nucleus) and its inactivation kinetics. Dialysis of the neuron with an ATP-free solution suppresses the T-current potentiation, whereas it becomes irreversible in the presence of ATPγS. Phosphorylation occurs when the channels are inactivated and is slowly removed when they recover from inactivation and remain in closed states (time constants of the induction and removal of the potentiation: 579 ± 143 msec and 4.9 ± 1.1 sec, respectively, at 25°C). The resulting apparent voltage sensitivity of this regulation follows the voltage dependence of the current steady-state inactivation. Thus, the current is paradoxically inhibited when the preceding hyperpolarization is lengthened, and maximal currents are generated after transient hyperpolarizations with a duration (0.7-1.5 sec) that is defined by the balance between the kinetics of the dephosphorylation and deinactivation. In addition, the phosphorylation will facilitate the generation of T current at resting membrane potential. This potentiation, which is specific to sensory thalamocortical neurons, would markedly influence the electroresponsiveness of these neurons and represent the first evidence of a regulation of native Cav3.1 channels.
Antagonist of the Amylin Receptor Blocks β-Amyloid Toxicity in Rat Cholinergic Basal Forebrain Neurons
Authors: Jhamandas Jack H. , MacTavish David
Published: June 2004

Salvage of cholinergic neurons in the brain through a blockade of the neurotoxic effects of amyloidβ protein (Aβ) is one of the major, but still elusive, therapeutic goals of current research in Alzheimer's disease (AD). To date, no receptor has been unequivocally identified for Aβ. Human amylin, which acts via a receptor composed of the calcitonin receptor-like receptor and a receptor-associated membrane protein, possesses amyloidogenic properties and has a profile of neurotoxicity that is strikingly similar to Aβ. In this study, using primary cultures of rat cholinergic basal forebrain neurons, we show that acetyl-[Asn30, Tyr32] sCT(8-37) (AC187), an amylin receptor antagonist, blocks Aβ-induced neurotoxicity. Treatment of cultures with AC187 before exposure to Aβ results in significantly improved neuronal survival as judged by MTT and live-dead cell assays. Quantitative measures of Aβ-evoked apoptotic cell death, using Hoechst and phosphotidylserine staining, confirm neuroprotective effects of AC187. We also demonstrate that AC187 attenuates the activation of initiator and effector caspases that mediate Aβ-induced apoptotic cell death. These data are the first to show that expression of Aβ toxicity may occur through the amylin receptor and suggest a novel therapeutic target for the treatment of AD.
Choline Transporter 1 Maintains Cholinergic Function in Choline Acetyltransferase Haploinsufficiency
Authors: Brandon Eugene P. , Mellott Tiffany , Pizzo Donald P. , Coufal Nicole , D'Amour Kevin A. , Gobeske Kevin , Lortie Mark , López-Coviella Ignacio , Berse Brygida , Thal Leon J. , Gage Fred H. , Blusztajn Jan Krzysztof
Published: June 2004

Choline acetyltransferase (ChAT), the enzyme that synthesizes the neurotransmitter acetylcholine (ACh), is thought to be present in kinetic excess in cholinergic neurons. The rate-limiting factor in ACh production is the provision of choline to ChAT. Cholinergic neurons are relatively unique in their expression of the choline transporter 1 (CHT1), which exhibits high-affinity for choline and catalyzes its uptake from the extracellular space to the neuron. Multiple lines of evidence indicate that the activity of CHT1 is a key determinant of choline supply for ACh synthesis. We examined the interaction of ChAT and ChT activity using mice heterozygous for a null mutation in theChatgene (Chat+/-). In these mice, brain ChAT activity was reduced by 40-50% relative to the wild type, but brain ACh levels as well as ACh content and depolarization-evoked ACh release in hippocampal slices were normal. However, the amount of choline taken up by CHT1 and ACh synthesizedde novofrom choline transported by CHT1 in hippocampal slices, as well as levels of CHT1 mRNA in the septum and CHT1 protein in several regions of the CNS, were 50-100% higher inChat+/- than inChat+/+ mice. Thus, haploinsufficiency of ChAT leads to an increased expression of CHT1. Increased ChT activity may compensate for the reduced ChAT activity inChat+/- mice, contributing to the maintenance of apparently normal cholinergic function as reflected by normal performance of these mice in several behavioral assays.
NADPH Oxidase Contributes to Angiotensin II Signaling in the Nucleus Tractus Solitarius
Authors: Wang Gang , Anrather Josef , Huang Jie , Speth Robert C. , Pickel Virginia M. , Iadecola Costantino
Published: June 2004

Angiotensin II (AngII), acting through angiotensin type 1 (AT1) receptors, exerts powerful effects on central autonomic networks regulating cardiovascular homeostasis and fluid balance; however, the mechanisms of AngII signaling in functionally defined central autonomic neurons have not been fully elucidated. In vascular cells, reactive oxygen species (ROS) generated by the enzyme NADPH oxidase play a major role in AngII signaling. Thus, we sought to determine whether NADPH oxidase is present in central autonomic neurons and, if so, whether NADPH oxidase-derived ROS are involved in the effects of AngII on these neurons. The present studies focused on the intermediate dorsomedial nucleus of the solitary tract (dmNTS) because this region receives autonomic afferents via the vagus nerve and is an important site of AngII actions. Using double-label immunoelectron microscopy, we found that the essential NADPH oxidase subunit gp91phoxis present in somatodendric and axonal profiles containing AT1receptors. The gp91phox-labeled dendrites received inputs from large axon terminals resembling vagal afferents. In parallel experiments using patch clamp of dissociated NTS neurons anterogradely labeled via the vagus, we found that AngII potentiates the L-type Ca2+currents, an effect mediated by AT1receptors and abolished by the ROS scavenger Mn(III) tetrakis (4-benzoic acid) porphyrin chloride. The NADPH oxidase assembly inhibitor apocynin and the peptide inhibitor gp91phoxdocking sequence, but not its scrambled version, also blocked the potentiation. The results provide evidence that NADPH oxidase-derived ROS are involved in the effects of AngII on Ca2+influx in NTS neurons receiving vagal afferents and support the notion that ROS are important signaling molecules in central autonomic networks.
Lhx6 Regulates the Migration of Cortical Interneurons from the Ventral Telencephalon But Does Not Specify their GABA Phenotype
Authors: Alifragis Pavlos , Liapi Anastasia , Parnavelas John G.
Published: June 2004

The LIM homeodomain family of transcription factors is involved in many processes in the developing CNS, ranging from cell fate specification to connectivity. A member of this family of transcription factors,lhx6, is expressed in the medial ganglionic eminence (MGE) of the ventral telencephalon, where the vast majority of cortical interneurons are generated. Its expression in the GABA-containing MGE cells that migrate to the cortex suggests that this gene uniquely or in combination with other transcription factors may play a role in the neurochemical identity and migration of these neurons. We performed loss of function studies forlhx6in mouse embryonic day 13.5 brain slices and dissociated MGE neuronal cultures using Lhx6-targeted small interfering RNA produced by a U6 promoter-driven vector. We found that silencinglhx6impeded the tangential migration of interneurons into the cortex, although it did not obstruct their dispersion within the ganglionic eminence. Blockinglhx6expression in dissociated MGE cultured neurons did not interfere with the production of GABA or its synthesizing enzyme. These results indicate thatlhx6, unlike the closely related memberlhx7, does not regulate neurotransmitter choice in interneurons but plays an important role in their migration from the ventral telencephalon to the neocortex.
Ligand-Dependent Activation of Slo Family Channels Is Defined by Interchangeable Cytosolic Domains
Authors: Xia Xiao-Ming , Zhang Xue , Lingle Christopher J.
Published: June 2004

Large-conductance Ca2+- and voltage-regulated K+channels (Slo1 BK-type) are controlled by two physiological stimuli, membrane voltage and cytosolic Ca2+. Regulation by voltage is similar to that in voltage-dependent K+channels, arising from positively charged amino acids primarily within the S4 transmembrane helices. The basis for regulation by Ca2+remains controversial. One viewpoint suggests that the extensive cytosolic C terminus contains the Ca2+regulatory machinery, whereas another suggests that the pore-forming module contains the Ca2+-sensing elements. To address this issue, we take advantage of another Slo family member, the pH-regulated homolog Slo3. We reason that if the ligand-sensing apparatus is uniquely associated with a particular domain (either the pore or the cytosolic domain), exchange of those domains between Slo1 and Slo3 should result in exchange of ligand dependence in association with the key domain. The results show that the Slo3 cytosolic module confers pH-dependent regulation on the Slo1 pore module, whereas the Slo1 cytosolic module confers Ca2+-dependent regulation on the Slo3 pore module. Thus, ligand-specific regulation is defined by interchangeable cytosolic regulatory modules.
The Juvenile Myoclonic Epilepsy GABAAReceptor α1 Subunit Mutation A322D Produces Asymmetrical, Subunit Position-Dependent Reduction of Heterozygous Receptor Currents and α1 Subunit Protein Expression
Authors: Gallagher Martin J. , Song Luyan , Arain Fazal , Macdonald Robert L.
Published: June 2004

Individuals with autosomal dominant juvenile myoclonic epilepsy are heterozygous for a GABAAreceptor α1 subunit mutation (α1A322D). GABAAreceptor αβγ subunits are arranged around the pore in a β-α-β-α-γ sequence (counterclockwise from the synaptic cleft). Therefore, each α1 subunit has different adjacent subunits, and heterozygous expression of α1(A322D), β, and γ subunits could produce receptors with four different subunit arrangements: β-α1-β-α1-γ (wild type); β-α1(A322D)-β-α1-γ (Hetβαβ); β-α1-β-α1(A322D)-γ (Hetβαγ);β-α1(A322D)-β-α1(A322D)-γ (homozygous). Expression of a 1:1 mixture of wild-type andα1(A322D) subunits with β2S and γ2S subunits (heterozygous transfection) produced smaller currents than wild type and much larger currents than homozygous mutant transfections. Western blot and biotinylation assays demonstrated that the amount of total and surface α1 subunit from heterozygous transfections was also intermediate between those of wild-type and homozygous mutant transfections. α1(A322D) mutations were then made in covalently tethered triplet (γ2S-β2S-α1) and tandem (β2S-α1) concatamers to target selectively α1(A322D) to each of the asymmetric α1 subunits. Coexpression of mutant and wild-type concatamers resulted in expression of either Hetβαβor Hetβαγreceptors. Hetβαβcurrents were smaller than wild type and much larger than Hetβαγand homozygous currents. Furthermore, Hetβαβtransfections contained less β-α concatamer than wild type but more than both Hetβαγand homozygous mutant transfections. Thus, whole-cell currents and protein expression of heterozygous α1(A322D)β2Sγ2S receptors depended on the position of the mutant α1 subunit, and GABAAreceptor currents in heterozygous individuals likely result primarily from wild-type and Hetβαβreceptors with little contribution from Hetβαγand homozygous receptors.
Morphine-Induced Changes in δ Opioid Receptor Trafficking Are Linked to Somatosensory Processing in the Rat Spinal Cord
Authors: Morinville Anne , Cahill Catherine M. , Aibak Haneen , Rymar Vladimir V. , Pradhan Amynah , Hoffert Cyrla , Mennicken Françoise , Stroh Thomas , Sadikot Abbas F. , O'Donnell Dajan , Clarke Paul B. S. , Collier Brian , Henry James L. , Vincent Jean-Pierre , Beaudet Alain
Published: June 2004

Anin vivofluorescent deltorphin (Fluo-DLT) internalization assay was used to assess the distribution and regulation of pharmacologically available δ opioid receptors (δORs) in the rat lumbar (L4-5) spinal cord. Under basal conditions, intrathecal injection of Fluo-DLT resulted in the labeling of numerous δOR-internalizing neurons throughout dorsal and ventral horns. The distribution and number of Fluo-DLT-labeled perikaryal profiles were consistent with that of δOR-expressing neurons, as revealed byin situhybridization and immunohistochemistry, suggesting that a large proportion of these cells was responsive to intrathecally administered δOR agonists. Pretreatment of rats with morphine for 48 hr resulted in a selective increase in Fluo-DLT-labeled perikaryal profiles within the dorsal horn. These changes were not accompanied by corresponding augmentations in either δOR mRNA or125I-deltorphin-II binding levels, suggesting that they were attributable to higher densities of cell surface δOR available for internalization rather than to enhanced production of the receptor. Unilateral dorsal rhizotomy also resulted in increased Fluo-DLT internalization in the ipsilateral dorsal horn when compared with the side contralateral to the deafferentation or to non-deafferented controls, suggesting that δOR trafficking in dorsal horn neurons may be regulated by afferent inputs. Furthermore, morphine treatment no longer increased Fluo-DLT internalization on either side of the spinal cord after unilateral dorsal rhizotomy, indicating that μOR-induced changes in the cell surface availability of δOR depend on the integrity of primary afferent inputs. Together, these results suggest that regulation of δOR responsiveness through μOR activation in this region is linked to somatosensory information processing.
DrosophilaSerpin 4 Functions as a Neuroserpin-Like Inhibitor of Subtilisin-Like Proprotein Convertases
Authors: Osterwalder Thomas , Kuhnen Angela , Leiserson William M. , Kim You-Seung , Keshishian Haig
Published: June 2004

The proteolytic processing of neuropeptide precursors is believed to be regulated by serine proteinase inhibitors, or serpins. Here we describe the molecular cloning and functional expression of a novel member of the serpin family,Serine protease inhibitor 4 (Spn4), that we propose is involved in the regulation of peptide maturation inDrosophila. TheSpn4gene encodes at least two different serpin proteins, generated by alternate splicing of the last coding exon. The closest vertebrate homolog to Spn4 is neuroserpin. Like neuroserpin, one of the Spn4 proteins (Spn4.1) features a unique C-terminal extension, reminiscent of an endoplasmic reticulum (ER) retention signal; however, Spn4.1 and neuroserpin have divergent reactive site loops, with Spn4.1 showing a generic recognition site for furin/SPC1, the founding member of the intracellularly active family of subtilisin-like proprotein convertases (SPCs).In vitro, Spn4.1 forms SDS-stable complexes with the SPC furin and directly inhibits it. When Spn4.1 is overexpressed in specific peptidergic cells ofDrosophilalarvae, the animals exhibit a phenotype consistent with disrupted neuropeptide processing. This observation, together with the unique combination of an ER-retention signal, a target sequence for SPCs in the reactive site loop, and thein vitroinhibitory activity against furin, strongly suggests that Spn4.1 is an intracellular regulator of SPCs.
Clinical Pharmacy Services, Pharmacy Staffing, and the Total Cost of Care in United States Hospitals
Authors: Bond C. A. , Raehl Cynthia L. , Franke Todd
Published: June 2004

This study evaluated direct relationships and associations among clinical pharmacy services, pharmacist staffing, and total cost of care in United States hospitals. A database was constructed from the 1992 American Hospital Association's Abridged Guide to the Health Care Field and the 1992 National Clinical Pharmacy Services Database. A multiple regression analysis, controlling for severity of illness, was employed to determine the relationships and associations. The study population consisted of 1016 hospitals. Six clinical pharmacy services were associated with lower total cost of care: drug use evaluation (p=0.001), drug information (p=0.003), adverse drug reaction monitoring (p=0.008), drug protocol management (p=0.001), medical rounds participation (p=0.0001), and admission drug histories (p=0.017). Two services were associated with higher total cost of care: total parenteral nutrition (TPN) team participation (p=0.001) and clinical research (p=0.0001). Total costs of care/hospital/year were lower when any of six clinical pharmacy services were present: drug use evaluation $1,119,810.18 (total $1,005,589,541.64 for the 898 hospitals offering the service), drug information $5,226,128.22 (total $1,212,461,747.04 for the 232 hospitals offering the service), adverse drug reporting monitoring $1,610,841.02 (total $1,101,815, 257.68 for the 684 hospitals offering the service), drug protocol management $1,729,608.41 (total $614,010,985.55 for the 355 hospitals offering the service), medical rounds participation $7,979,720.45 (total $1,212,917,508.41 for the 152 hospitals offering the service), and admission drug histories $6,964,145.17 (total $208,924,355.10 for the 30 hospitals offering the service). Clinical research $9,558,788.01 (total $1,013,231,529.06 for the 106 hospitals offering the service) and TPN team participation $3,211,355.12 (total $1,027,633,638.43 for the 320 hospitals offering the service) were associated with higher total costs of care. As staffing increased for hospital pharmacy administrators (p=0.0001) and clinical pharmacists (p=0.007), total cost of care decreased. As staffing increased for dispensing pharmacists, total cost of care increased (p=0.006). Based on this total cost of care model, optimal hospital pharmacy administrator staffing was 2.01/100 occupied beds. Staffing for dispensing pharmacists should be as low as possible, and definitely fewer than 5.11/100 occupied beds. Staffing for clinical pharmacists should be as high as possible, but definitely more than 1.11/100 occupied beds. The results of this study suggest that increased staffing levels of clinical pharmacists and pharmacy administrators, as well as some clinical pharmacy services, were associated with reduced total cost of care in United States hospitals.
Incidence of First‐Time Idiopathic Seizures in Users of Tramadol
Authors: Gasse Ms. Christiane , Derby Laura , Vasilakis‐Scaramozza Catherine , Jick Hershel
Published: June 2004

Study Objective. To assess the risk of idiopathic incident seizures among patients who ever took tramadol.

Design. Nested case‐control design.

Setting. General Practice Research Database from November 1996–August 1998.

Patients. Eleven thousand three hundred eighty‐three patients.

Intervention. Comparison of risks of idiopathic incident seizures during exposed and unexposed times among patients who had ever taken tramadol and other analgesics with 90‐day follow‐up.

Measurements and Main Results. Among the 11,383 subjects we identified 21 cases of idiopathic seizures, 10 of which were categorized as definite cases and 11 categorized as possible cases. Three patients were exposed to tramadol alone in the previous 90 days, 10 to opiates, three to both tramadol and opiates, one to other analgesics, and four to no analgesics.

Conclusion. The risk of idiopathic seizures was similarly elevated in each analgesic exposure category compared with nonusers, suggesting that the risk for patients taking tramadol was not increased compared with other analgesics.

(Pharmacotherapy 2000; 20(6):629–634)
Comparison of the Serum and Intracellular Pharmacokinetics of Azithromycin in Healthy and Diabetic Volunteers
Authors: Ernst Erika J. , Klepser Michael E. , Klepser Teresa B. , Nightingale Charles H. , Hunsicker Lawrence G.
Published: June 2004

Study Objective. To compare serum and intracellular pharmacokinetics of azithromycin in healthy volunteers and patients with diabetes.

Design. Open‐label, parallel study.

Setting. Clinical research center.

Subjects. Twelve patients with diabetes and 12 healthy volunteers.

Interventions. Subjects were given a single 500‐mg dose of azithromycin followed by 250 mg/day for 2 days. Blood samples were obtained just before and after the third dose for up to 24 hours for serum and 168 hours for intracellular measurement of azithromycin.

Measurements and Main Results. Pharmacokinetic parameters were calculated by noncompartmental methods and compared with a t test. The groups did not differ in maximum concentration, time to maximum concentration, or area under the concentration‐time curve in serum or polymorphonuclear cells (PMNs). Differences in the PMN:serum ratio were observed at the 24‐hour time point (healthy 1209 ± 432, diabetic 859 ± 286, p= 0.051).

Conclusion. In general, the pharmacokinetics of azithromycin are comparable in diabetics and healthy volunteers. Accumulation of drug in macrophages was slightly lower in patients.
Comparative In Vitro Activity of Vancomycin and Levofloxacin in Combination with Rifampin Against Planktonic versus Sessile Cells of Staphylococcus epidermidis
Authors: Kang‐Birken S. Lena
Published: June 2004

Study Objective. To evaluate the activity of vancomycin and levofloxacin alone and combined with rifampin against planktonic and sessile cells.

Intervention. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the three drugs were determined against a clinical isolate of methicillin‐resistant Staphylococcus epidermidis (MRSE 23) and a reference strain of MRSE (ATCC 35984).

Measurements and Main Results. The MICs/MBCs of vancomycin, levofloxacin, and rifampin against MRSE 23 were 0.78/0.78 μg/ml, 0.19/0.19 μg/ml or below, and 0.19/0.19 μg/ml or below, and against ATCC 35984 were 0.78/1.56 μg/ml, 0.19/0.19 μg/ml or below, and 0.19/0.19 μg/ml or below, respectively. A 99.9% killing activity was achieved with vancomycin, levofloxacin, and vancomycin‐levofloxacin against planktonic cells of MRSE 23 (18.9, 21.3, and 17.5 hrs, respectively) and only with levofloxacin against ATCC 35984 (21.5 hrs). No regimen achieved 99.9% killing activity against sessile cells.

Conclusion. Adding rifampin was antagonistic against planktonic cells and had an additive effect against sessile cells. Activity typically reported using nutrient‐rich, planktonic cells may not be applicable to sessile cells under environmental and growth restrictions.
Evaluation of Echinacea for Treatment of the Common Cold
Authors: Giles Joel T. , Palat Cuthbert T. , Chien Susan H. , Chang Ziba Gorji , Kennedy Daniel T.
Published: June 2004

Considered to have immunostimulating activity, echinacea is a widely used phytomedicinal for treatment of the common cold and upper respiratory tract infections (URTIs). We reviewed the literature from the MEDLINE database (January 1966–July 1999), International Pharmaceutical Abstracts (IPA) online database, Cambridge Scientific Abstracts Biological Sciences online database, Alt‐Health Watch online database, EMBase CD‐ROM database, and references from published articles, reviews, and letters to evaluate evidence from clinical trials of echinacea's purported efficacy for treating or preventing URTIs. Twelve clinical studies published from 1961–1997 concluded that echinacea was efficacious for treating the common cold, but the results are unclear due to inherent flaws in study design. Five trials were published since 1997; two showed that echinacea lacked efficacy for treating and preventing URTI symptoms, and three concluded that it was effective in reducing the frequency, duration, and severity of common cold symptoms. Again, these results are unclear because of methodologic uncertainties, such as small populations and use of noncommercially available, nonstandardized dosage forms. Although evidence for echinacea's efficacy is inconclusive, it appears to be safe. Patients without contraindications to it may not be dissuaded from using an appropriate preparation to treat the common cold.
Update on the Interaction Between Aspirin and Angiotensin‐Converting Enzyme Inhibitors
Authors: Nawarskas James J. , Spinler Sarah A.
Published: June 2004

We summarized recent published literature regarding the significance of an interaction between aspirin and angiotensin‐converting enzyme (ACE) inhibitors in patients with various cardiovascular diseases. A MEDLINE search (January 1998–July 1999) was performed and abstracts from the 1999 American College of Cardiology and 1998 American Heart Association annual scientific sessions were reviewed to identify pertinent studies. Material for discussion was identified through a MEDLINE search from January 1996–July 1999 and through cited references. The results of several studies added to our understanding of the clinical ramifications of an aspirin‐ACE inhibitor interaction, but also introduced questions. These studies are largely contradictory, but do reiterate the possibility of an interaction, if only in certain subsets of patients. Low dosages (≤ 100 mg/day) of aspirin appear to be safer in this regard than higher dosages. The frequency and severity of the interaction and possible predisposing factors await future research.
Non‐Ergot Dopamine Agonist‐Induced Sleep Attacks
Authors: Ryan Melody , Slevin John T. , Wells Ammie
Published: June 2004

Two patients with Parkinson's disease received treatment with ropinirole and/or pramipexole, during which both experienced sleep attacks. These attacks may be a class effect of non‐ergot dopamine agonists. Health care professionals should be aware of the potential of these agents to cause sleep attacks and caution patients about this potentially life‐threatening adverse effect.
Use of Fenofibrate in the Management of Protease Inhibitor‐Associated Lipid Abnormalities
Authors: Thomas James C. , Lopes‐Virella Maria F. , Del Bene Victor E. , Cerveny Joli D. , Taylor Kelly B. , McWhorter Laura S. , Bultemeier Nanette C.
Published: June 2004

Human immunodeficiency virus (HIV) protease inhibitors are associated with several metabolic abnormalities including hypercholesterolemia and hypertriglyceridemia. Fenofibrate is a new lipid‐lowering agent for adults with very high triglyceride levels that was administered to two HIV‐positive patients who were taking protease inhibitors and developed hypertriglyceridemia. Starting dosages were 134 and 201 mg/day, and were increased to 268 mg/day in both patients. Triglyceride levels decreased from 1450 to 337 mg/dl (76.8%) and from 1985 to 322 mg/dl (83.8%), respectively, after 10 months of therapy. High‐density lipoprotein levels increased in both patients.
Benzocaine‐Induced Methemoglobinemia During an Outpatient Procedure
Authors: Wurdeman Richard L. , Mohiuddin Syed M. , Holmberg M. Jeff , Shalaby Alaa
Published: June 2004

Outpatient transesophageal echocardiography was performed in a 69‐year‐old man with a history of aortic valve repair. During the procedure the patient became markedly cyanotic and hypotensive. Oxygen saturation measured by pulse oximetry decreased from 97% to the mid‐80s. The man's condition continued to deteriorate. On transfer to a critical care unit, blood analysis by co‐oximetry showed methemoglobin saturation of 67.8%. The patient's condition improved significantly after intravenous administration of methylene blue 1 mg/kg. With increasing numbers of outpatient procedures performed under topical anesthesia, measures should be in place to deal with a potential life‐threatening adverse event such as methemoglobinemia.
A Dose‐Escalation Study of the Safety, Tolerability, and Pharmacokinetics of Intravenous Gatifloxacin in Healthy Adult Men
Authors: Gajjar Diptee A. , LaCreta Frank P. , Uderman Howard D. , Kollia Georgia D. , Duncan Glenn , Birkhofer Martin J. , Grasela Dennis M.
Published: June 2004

Study Objectives. To examine single‐ and multiple‐dose safety, tolerability and pharmacokinetics of gatifloxacin administered as daily 1‐hour intravenous infusions for 14 days, and to determine the effect of gatifloxacin on glucose tolerance, pancreatic β‐cell function, and electrocardiogram (ECG).

Design. Randomized, double‐blind, placebo‐controlled, ascending‐dose study.

Setting. Bristol‐Myers Squibb, Clinical Pharmacology Unit, Princeton, New Jersey, USA.

Patients. Forty healthy male subjects, eight in each of five groups, were enrolled to receive sequential doses of gatifloxacin: 200 mg (10 mg/ml), 200 mg (1 mg/ml), and 400, 600, and 800 mg (2 mg/ml); six subjects per group received active drug and two received placebo.

Interventions. A single dose of the drug was administered as an intravenous infusion over 1 hour. After a 72‐hour washout period, the drug was administered once/day for 14 days by 1‐hour intravenous infusion. Physical examinations, ECGs, spirometry, and clinical laboratory tests, including glucose tolerance test (GTT) and assessment of glucose homeostasis, were performed before treatment and on selected dosing days. A safety evaluation was performed before escalating doses. No intrasubject dose escalation was permitted.

Measurements and Main Results. The pharmacokinetics of gatifloxacin were dose linear and time independent after intravenous administration over the range of 200–800 mg. After daily repeated administration, a predictable, modest accumulation was observed; steady state was reached by the third dose. Approximately 80% of the dose was recovered as unchanged drug in urine. Mean changes (before the first dose to the last dose) after oral GTT and in fasting serum glucose, insulin, and C‐peptide concentrations were comparable among the gatifloxacin and placebo treatment groups. A mild, transient decrease in serum glucose was associated with the end of the 1‐hour infusion of gatifloxacin. No clinically important changes in QTc interval or spirometry occurred. The most frequent treatment‐related adverse effects were local intravenous site reactions, which were associated with dose and/or concentration of intravenous solution.

Conclusion. Gatifloxacin was safe and well tolerated at intravenous doses of up to 800 mg/day for 14 days. Gatifloxacin pharmacokinetics were linear and time independent.
Interchangeability of 400‐mg Intravenous and Oral Gatifloxacin in Healthy Adults
Authors: LaCreta Frank P. , Kaul Sanjeev , Kollia Georgia D. , Duncan Glenn , Randall Dianne M. , Grasela Dennis M.
Published: June 2004

Study Objective. To evaluate the interchangeability of 400‐mg intravenous and oral doses of gatifloxacin.

Design. Randomized, open‐label, crossover study.

Setting. GFI Pharmaceutical Services, Inc., Evansville, Indiana, USA.

Subjects. Twenty‐four healthy men and women (12 of each gender), aged 18–42 years.

Interventions. Subjects received single doses of gatifloxacin 400 mg either by intravenous infusion over 1 hour or a 400‐mg tablet orally with 240 ml of water, each dose separated by a 1‐week washout. Plasma concentrations of gatifloxacin were determined by a validated high‐performance liquid chromatography; pharmacokinetic parameters were calculated using noncompartmental methods. Distributions of pharmacokinetic parameter values were summarized by route of administration and gender. Effects of treatment on pharmacokinetic parameter values of gatifloxacin were assessed by an analysis of variance model suitable for a two‐way, two‐treatment, crossover design. Clinical evaluations were performed to assess drug safety and tolerability.

Measurements and Main Results. Intravenous and oral gatifloxacin were considered interchangeable because both routes were bioequivalent with respect to area under the curve (AUC; 90% confidence interval for the ratio of geometric means contained within 0.8–1.25). The plasma concentration‐time profile after intravenous administration was similar and comparable in extent of exposure (AUC0–∞) with that for the oral route when equal doses were administered to men and women. The absolute bioavailability of gatifloxacin after oral administration was 96%, consistent with bioequivalence of the 400‐mg intravenous and oral doses. The drug was well tolerated; the frequency of adverse events was comparable after intravenous and oral administration.

Conclusion. Intravenous and tablet formulations of gatifloxacin are bioequivalent and therefore interchangeable. This permits greater flexibility in choosing oral or parenteral therapy, with the possibility of avoiding hospitalization based on knowledge that oral administration will deliver therapeutic exposure to the drug, or abbreviating hospital stay due to ease of switching from intravenous to oral therapy.
Effect of Multiple‐Dose Gatifloxacin or Ciprofloxacin on Glucose Homeostasis and Insulin Production in Patients with Noninsulin‐Dependent Diabetes Mellitus Maintained with Diet and Exercise
Authors: Gajjar Diptee A. , LaCreta Frank P. , Kollia Georgia D. , Stolz Randall R. , Berger Sheldon , Smith William B. , Swingle Mary , Grasela Dennis M.
Published: June 2004

Study Objectives. To compare the effects of gatifloxacin and ciprofloxacin on glucose homeostasis, including glucose tolerance test (GTT), pancreatic β‐cell function, and insulin production and secretion in patients with noninsulin‐dependent (type 2) diabetes mellitus (NIDDM) maintained with diet and exercise; and to evaluate the pharmacokinetics, safety, and tolerability of gatifloxacin.

Design. Randomized, double‐blind, placebo‐controlled, multiple‐dose study.

Setting. GFI Pharmaceutical Services, Inc., Evansville, Indiana; Chicago Center for Clinical Research, Chicago, Illinois; and New Orleans Center for Clinical Research, New Orleans, Louisiana, USA.

Patients. Forty‐eight men and women with NIDDM.

Interventions. Patients were assigned sequentially at enrollment to receive gatifloxacin 400 mg/day orally, ciprofloxacin 500 mg twice/day orally, or placebo for 10 days. Oral GTTs were performed on specific days throughout the study, as well as measurements of serum glucose, serum insulin, and C‐peptide levels. Physical examinations, electrocardiograms, spirometry, and clinical laboratory tests were performed before dosing and on selected dosing days.

Measurements and Main Results. Gatifloxacin had no significant effect on glucose tolerance and pancreatic β‐cell function, as shown by oral GTT results and insulin and C‐peptide levels. Fasting glucose levels 0–6 hours after gatifloxacin administration on days 1 and 10 showed a downward trend, but it was not significant compared with placebo; results were similar with ciprofloxacin. Gatifloxacin also lacked a long‐term effect on fasting insulin levels, but this was not shown for a short‐term effect, suggesting a modest, transient effect on insulin release. On the other hand, ciprofloxacin had no short‐term effect but produced a more sustained effect on insulin release and production. The pharmacokinetics of gatifloxacin in patients with NIDDM were similar to those in healthy subjects. Overall, subjects tolerated treatment well. All reported drug‐related adverse events were mild to moderate in intensity. The frequency of adverse events was similar in gatifloxacin‐ and ciprofloxacin‐treated patients, and only slightly higher than in placebo‐treated patients.

Conclusion. Gatifloxacin was well tolerated in patients with NIDDM controlled by diet and exercise. It had no significant effect on glucose homeostasis, β‐cell function, or long‐term fasting serum glucose levels, but it did cause a brief increase in serum insulin levels.
Safety and Pharmacokinetics of a Single Oral Dose of Gatifloxacin in Patients with Moderate to Severe Hepatic Impairment
Authors: Grasela Dennis M. , Christofalo Barbara , Kollia Georgia D. , Duncan Glenn , Noveck Robert , Manning James A. , LaCreta Frank P.
Published: June 2004

Study Objectives. To assess the safety and pharmacokinetics of oral gatifloxacin 400 mg in subjects with and without hepatic impairment, and the need to modify doses in patients with hepatic dysfunction.

Design. Single‐dose, nonrandomized, open‐label, parallel‐group study.

Setting. Clinical Research Center, New Orleans, Louisiana.

Patients. Eight subjects with grade B or C hepatic dysfunction (Child‐Pugh classification) and eight age‐, weight‐, and gender‐matched subjects with normal hepatic function.

Interventions. After a single oral dose of gatifloxacin 400 mg, blood and urine samples were collected at specified times or intervals over 48 hours to determine drug concentrations.

Measurements and Main Results. All 16 subjects (7 with grade B and 1 with grade C hepatic impairment, 8 with normal hepatic function) completed the study. Peak plasma concentration (Cmax) and area under the plasma concentration‐time curve (AUC0–∞) for gatifloxacin were 32% and 22% higher, respectively, in subjects with hepatic impairment. Except for Cmax, the ratio of means for AUC satisfied the specified criterion (0.67–1.50) for lack of effect. There were no statistically significant differences in any other pharmacokinetic values except apparent oral clearance (ClT/F). All treatment‐emergent adverse events were mild or moderate in intensity and resolved before subjects were discharged from the study.

Conclusion. Modest increases in Cmax and AUC0–∞ are not anticipated to have a negative effect on the outcome of therapy in hepatically impaired subjects, nor are they anticipated to result in adverse drug reactions. Patients with moderate to severe (Child‐Pugh grade B or C) hepatic dysfunction do not require gatifloxacin dose adjustments. In addition, the similarity in half‐life (t1/2) for the groups (8.9 hrs for hepatically impaired subjects, 9.3 hrs for controls) suggests that no difference would be anticipated in the extent of drug accumulation after multiple doses. The overall safety and tolerability of a single oral dose of gatifloxacin 400 mg were excellent in both healthy subjects and those with hepatic impairment.
The Risk of Gastrointestinal Bleed, Myocardial Infarction, and Newly Diagnosed Hypertension in Users of Meloxicam, Diclofenac, Naproxen, and Piroxicam
Authors: Jick Susan S.
Published: June 2004

Study Objective. To obtain formally quantified data on the relation of meloxicam to newly diagnosed gastrointestinal problems, myocardial infarction, or treated hypertension.

Design. Nested case‐control study.

Setting. United Kingdom‐based General Practice Research Database.

Patients. Patients who received prescriptions for meloxicam, diclofenac, naproxen, or piroxicam formed the study population. Cases were people who developed gastrointestinal problems, myocardial infarction, or hypertension.

Measurements and Main Results. Relative risk estimates for developing the study outcomes were provided for each study nonsteroidal antiinflammatory drug (NSAID), with diclofenac as the reference drug. In no instance was meloxicam associated with an increased risk for a study outcome.

Conclusion. Compared with the other NSAIDs, meloxicam was not materially associated with any study outcomes. This study provides reassurance to those prescribing this newer class of NSAIDs.
Lack of Interaction Between Citalopram and the CYP3A4 Substrate Triazolam
Authors: Nolting Arno , Abramowitz Wattanaporn
Published: June 2004

Study Objectives. To determine the effect of the selective serotonin reuptake inhibitor citalopram on plasma levels of triazolam, and to determine the effect of a single dose of triazolam on steady‐state levels of citalopram and its major metabolites.

Design. Open‐label, multidose study.

Setting. Clinical Studies, Ltd., Fort Lauderdale, Florida.

Participants. Eighteen healthy male and female volunteers.

Interventions. Subjects received triazolam 0.25 mg alone and another 0.25mg dose after 4 weeks of citalopram 20 mg/day for 1 week, followed by 3 weeks of citalopram 40 mg/day.

Measurements and Main Results. Pharmacokinetic parameters were determined after single‐dose administration of triazolam alone, after administration of citalopram alone at steady state, and after coadministration of the drugs. The pharmacokinetics of triazolam and its metabolite α‐hydroxytriazolam were unchanged by citalopram coadministration. Triazolam appeared to be absorbed slightly more quickly during coadministration. Citalopram kinetics were unaffected by coadministration.

Conclusion. No pharmacokinetic interaction between the drugs was observed, suggesting that triazolam and other cytochrome P450 3A4 substrates can be coadministered safely with citalopram.

(Pharmacotherapy 2000; 20(7):750–755)