Metallochaperones and metal-transporting ATPases: a comparative analysis of sequences and structures

A comparative structural genomic analysis of a new class of metal-trafficking proteins can provide insights into the intracellular chemistry of reactive cofactors such as copper and zinc. Starting from the sequences of the metallochaperone Atx1 and from the first soluble domain of the copper-transporting ATPase Ccc2, both from yeast, a search on the available genomes was performed using a homology criterion and a metal-binding motif x'-x"-C-x'-x'-C. By limiting ourselves to 20% identity with any of the proteins found, several soluble copper-transport proteins were identified, as well as soluble domains of membrane-bound ATPases. Structural models were calculated using high-resolution solution structures as templates, and the models were validated using statistical and energy criteria. Residue conservation and substitution have been interpreted and discussed in terms of structure-function relationship. The potential energy surfaces have been analyzed in terms of protein-protein interactions. We find that metallochaperones and their physiological partner ATPases from several phylogenetic kingdoms recognize one another, via an interplay of electrostatics, hydrogen bonding, and hydrophobic interactions, in a manner that precisely orients the metal-binding side chains for rapid metal transfer between otherwise tight binding sites. Finally, other putative metal-transport proteins are mentioned that have low homology and/or a different metal-binding consensus motif and that appear to use similar structures for recognition and transfer. This analysis highlights the wealth and the complexity of the field.     

Decrease in efficacy and potency of nonsteroidal anti-inflammatory drugs by chronic delta(9)-tetrahydrocannabinol administration

Cannabinoids have been shown to increase the release of arachadonic acid, whereas nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to decrease the analgesic effects of cannabinoids. We evaluated the antinociceptive effects of chronic administration of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), anandamide (an endogenous cannabinoid), arachadonic acid, ethanolamine, and methanandamide on several NSAIDs via p.o. and/or i.p. routes of administration using the mouse p-phenylquinone (PPQ) test, a test for visceral nociception. Our studies with a cannabinoid receptor (CB1) antagonist [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboximide hydrochloride (SR141716A)], a CB2 antagonist [N-((1S)-endo-1,3,3-trimethyl-bicyclo-heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide) (SR144528)], and an another CB2 agonist [1,1-dimethylbutyl-1-deoxy-Delta(9)-THC (JWH-133)] were performed to better characterize PPQ interactions with cannabinoid receptors. The acute affects of Delta(9)-THC were blocked by SR141716A (i.p.) and partially blocked by SR144528 (i.p.). When NSAIDs (p.o.) were administered, the ED(50) values were as follows: 23 mg/kg aspirin, 3 mg/kg indomethacin, 5 mg/kg celecoxib, 3 mg/kg ketorolac, 57 mg/kg acetaminophen (32.3-99.8), and 0.8 mg/kg diclofenac (0.1-4.9). In animals given chronic Delta(9)-THC, only diclofenac and acetaminophen were active. Conversely, chronic methanandamide (i.p.) did not alter the antinociceptive effects of the NSAIDs. Neither the CB1 or CB2 antagonist blocked the effects of the NSAIDs. The effects of chronic arachadonic acid, ethanolamine, and anandamide could not be evaluated. In summary, our data indicate that chronic Delta(9)-THC alters the cyclooxygenase system. Alternatively, the data suggest that this alteration is not due to chronic endogenous cannabinoid release. Based upon these data, we hypothesize that human subjects who are chronic users of Delta(9)-THC may not respond to analgesic treatment with the above NSAIDs.     

The use of benzodiazepines in the treatment of chest pain: a review of the literature

Benzodiazepines, although not listed in the American Heart Association's guidelines for the treatment of chest pain, are often used to provide symptomatic relief to patients who experience chest pain. To investigate the utility of benzodiazepines in the treatment of chest pain, the pharmacologic actions and cardiovascular effects of benzodiazepines were reviewed. In addition, a literature search regarding the use of benzodiazepines to treat patients with chest pain was conducted. The results indicated that benzodiazepines reduce anxiety, pain, and cardiovascular activation. Benzodiazepines amplify gamma-aminobutyric acid (GABA) throughout the central nervous system, and act more peripherally to reduce catecholamines. In addition, preliminary evidence indicates that benzodiazepines may cause coronary vasodilatation, prevent dysrhythmias, and block platelet aggregation, though further study is needed. Both non-cardiac chest pain (associated with musculoskeletal, esophageal, neurologic, and psychiatric conditions) and cardiac chest pain (associated with acute and chronic myocardial ischemia) seem to be effectively treated with benzodiazepines. Benzodiazepines are safe and well tolerated when administered alone or in combination with other medications. Moreover, the risk of dependence is minimal when benzodiazepines are prescribed on a short-term basis. Further study of benzodiazepines in the treatment of acute chest pain is needed to confirm these favorable actions and better define their use in the acute medical setting.     

Capacity Decisions in the General Hospital: When Can You Refuse to Follow a Person's Wishes?

LESSONS LEARNED AT THE INTERFACE OF MEDICINE AND PSYCHIATRY: The Psychiatric Consultation Service at Massachusetts General Hospital (MGH) sees medical and surgical inpatients with comorbid psychiatric symptoms and conditions. Such consultations require the integration of medical and psychiatric knowledge. During their thrice-weekly rounds, Dr. Huffman and Dr. Stern discuss the diagnosis and management of conditions confronted. These discussions have given rise to rounds reports that will prove useful for clinicians practicing at the interface of medicine and psychiatry.     

QTc Prolongation and the Use of Antipsychotics: A Case Discussion

LESSONS LEARNED AT THE INTERFACE OF MEDICINE AND PSYCHIATRY: The Psychiatric Consultation Service at Massachusetts General Hospital (MGH) sees medical and surgical inpatients with comorbid psychiatric symptoms and conditions. Such consultations require the integration of medical and psychiatric knowledge. During their thrice-weekly rounds, Dr. Huffman and Dr. Stern discuss the diagnosis and management of conditions confronted. These discussions have given rise to rounds reports that will prove useful for clinicians practicing at the interface of medicine and psychiatry.     

Indole naphthyridinones as inhibitors of bacterial enoyl-ACP reductases FabI and FabK

Bacterial enoyl-ACP reductase (FabI) is responsible for catalyzing the final step of bacterial fatty acid biosynthesis and is an attractive target for the development of novel antibacterial agents. Previously we reported the development of FabI inhibitor 4 with narrow spectrum antimicrobial activity and in vivo efficacy against Staphylococcus aureus via intraperitoneal (ip) administration. Through iterative medicinal chemistry aided by X-ray crystal structure analysis, a new series of inhibitors has been developed with greatly increased potency against FabI-containing organisms. Several of these new inhibitors have potent antibacterial activity against multidrug resistant strains of S. aureus, and compound 30 demonstrates exceptional oral (po) in vivo efficacy in a S. aureus infection model in rats. While optimizing FabI inhibitory activity, compounds 29 and 30 were identified as having low micromolar FabK inhibitory activity, thereby increasing the antimicrobial spectrum of these compounds to include the FabK-containing pathogens Streptococcus pneumoniae and Enterococcus faecalis. The results described herein support the hypothesis that bacterial enoyl-ACP reductases are valid targets for antibacterial agents.     

Selective attention affects human brain stem frequency-following response

Selective attention modifies long-latency cortical event-related potentials. Amplitudes are typically enhanced and/or latencies reduced when evoking stimuli are attended. However, there is controversy concerning the effects of selective attention on short-latency brain stem evoked potentials. The objective of the present study was to assess possible attention effects on the brain stem auditory frequency-following response (FFR) elicited by a periodic tone. Young adult subjects heard a repetitive auditory stimulus while detecting infrequent target stimuli in either an auditory or visual detection task. Five channels of high frequency electroencephalographic (EEG) activity were recorded along the scalp midline with the center electrode positioned at the vertex. The FFR was elicited by the repetitive tone during both tasks. There were significant individual differences in the electrode sites yielding maximum response amplitudes, but overall FFR amplitudes were significantly larger during the auditory attention task. These results suggest that selective attention in humans can modify signal processing in sensory (afferent) pathways at the level of the brain stem. This may reflect top-down perceptual preprocessing mediated by extensive descending (efferent) pathways that originate in the cortex. Overall, the FFR appears to be a robust indicator of early auditory neural processing and shows effects not seen in brain stem auditory evoked response studies employing transient (click) acoustic stimuli.     

Relieving Dyspareunia

Effective treatment of dyspareunia can be a simple matter of reassuring the patient or conferring with her sexual partner. Or it may require vaginal dilation, use of lubricant or estrogenic cream, or surgery. Psychogenic dyspareunia is relatively uncommon.