Detection of major genes underlying several quantitative traits associated with a common disease using different ascertainment schemes

Using the Problem 2A data sets of GAW10, we assessed the power of four ascertainment schemes to localize major genes underlying a disease trait; the schemes were based on disease or quantitative trait status of nuclear families. MAPMAKER/SIBS was used to perform sib-pair analysis for all four data sets using marker data from three chromosomes, 4, 5 and 8. Each scheme varied in power to identify major genes underlying the quantitative traits depending on the genetic architecture of the data set. Three different methods, Haseman-Elston quantitative trait locus (QTL) regression analysis, maximum likelihood variance estimation and a non-parametric method, were used to assess the strength of linkage in all four data sets. False positive mappings localizing to the same region of the genome, verifiable across all three methods did not occur. Two major genes, MG1 and MG2, were successfully assigned to chromosomes 5 and 8, respectively, by at least one of the ascertainment schemes. MG1 was localized under two schemes, selection of families with exactly two affected sibs and selection of families with two sibs who had extremely discordant values for Q1. Additional weak evidence of the location of MG1 was also obtained under the other two ascertainment schemes. MG2 could not be detected by analyzing data sets ascertained either by affected sib pairs or by sib pairs with extremely discordant values for Q1. In the data set ascertained by a third strategy, selection of families with sib pairs extremely discordant for Q2, MG2 could be mapped to chromosome 8. A random ascertainment scheme yielded a data set in which we could find weak evidence for MG1 and no evidence for MG2. Thus our ability to detect major genes underlying the QTL depended on several factors which included the ascertainment scheme, the population allele frequencies, linkage and epistasis.

Effect of acute and subchronic subcutaneous urocortin on blood pressure and food consumption in ob/ob mice

Corticotropin-releasing factor and urocortin belong to a hypothalamic peptide family thought to be important in appetite regulation. The present study compared the appetite-suppressant effect of subcutaneous urocortin in obese mice to its cardiovascular effects. Acutely, urocortin (100 nmol/kg iv) reduced blood pressure and increased heart rate in urethane anesthetized nonobese mice; effects similar to those produced by subcutaneous urocortin (10 and 100 nmol/kg sc) in nonobese and ob/ob mice. Over this same dose range (10-100 nmol/kg sc), urocortin dramatically inhibited food consumption in the ob/ob mouse. To determine if the acute hypotensive effect of urocortin (10 nmol/kg sc) in the ob/ob mouse persisted after repeated urocortin administration, animals were pretreated for 3 days with urocortin (10 nmol/kg sc) or vehicle. Following urocortin pretreatment, urocortin-induced hypotension was similar to the effect in vehicle pretreated mice. However, urocortin-induced appetite suppression was reduced following 3 days of pretreatment with urocortin (10 nmol/kg sc) to ob/ob mice. These data suggest that the hypotensive and appetite-suppressant effects of urocortin are mediated by different mechanisms and tolerance to the hypotension did not readily occur in obese animals.

Study of the analgesic effect of lanepitant in patients with osteoarthritis pain

OBJECTIVE

Lanepitant selectively blocks substance P binding to the neurokinin-1 receptor, preventing neurogenic inflammation and pain transmission. Substance P is present in synovial fluid and in excess in cerebral spinal fluid. We investigated the effect of lanepitant on pain caused by osteoarthritis to evaluate the role of neurokinin-1 blockade.

METHODS

Outpatients (n = 214) with moderate to severe lower-limb osteoarthritis pain were treated for 3 weeks in a parallel, randomized double-blind study with initial doses of 20, 60, 200, or 600 mg lanepitant, 375 mg naproxen, or placebo, followed by 10, 30, 100, or 300 mg lanepitant twice a day, 375 mg naproxen twice a day, or placebo twice a day in the multiple-dose period. Pain intensity, pain relief, patient global impression, and adjunctive analgesic use were compared across treatments. Safety was evaluated with adverse events, vital signs, and laboratory assessments.

RESULTS

There was no statistically significant difference in efficacy or safety across treatments for the initial dose assessment. After 1 week of therapy, naproxen was statistically significantly (P < .05) better than placebo and lanepitant in reducing average pain. During the second and third weeks of therapy, patients receiving naproxen continued to have statistically significantly (P < .05) less pain than those receiving placebo or lanepitant despite using significantly less adjunctive analgesic medication. There were no statistically significant differences in rates of discontinuation across treatments. Lanepitant treatment was associated with diarrhea, whereas naproxen treatment was associated with gastric discomfort. There were no clinically relevant changes in vital signs or laboratory analytes for any of the treatments.

CONCLUSION

Lanepitant was ineffective in relieving osteoarthritis pain, possibly because neurokinin-1 binding of substance P does not play a significant role in osteoarthritis pain or because lanepitant fails to adequately penetrate the blood-brain barrier to affect central pain perception.

Clinical outcome after short-term psychotherapy for adolescents with major depressive disorder

BACKGROUND

Cognitive behavioral therapy has been shown to be more efficacious than alternative psychosocial interventions for the acute treatment of adolescents with major depressive disorder. However, the long-term impact of brief psychosocial interventions on the course of adolescent depression is not well established.

METHODS

One hundred seven adolescents with major depressive disorder randomly assigned to 12 to 16 weeks of cognitive behavioral therapy, systemic behavioral family therapy, or nondirective supportive therapy were evaluated for 2 years after the psychotherapy trial to document the subsequent course and predictors of major depressive disorder.

RESULTS

There were no long-term differential effects of the 3 psychotherapies. Most participants (80%) recovered (median time, 8.2 months from baseline), and 30% had a recurrence (median time, 4.2 months from recovery). Twenty-one percent were depressed during at least 80% of the follow-up period. Severity of depression (at baseline) and presence of self-reported parent-child conflict (at baseline and during the follow-up period) predicted lack of recovery, chronicity, and recurrence. Despite the similarity to clinically referred patients at baseline, patients recruited via advertisement were less likely to experience a recurrence.

CONCLUSIONS

There were no significant differences in long-term outcome among cognitive behavioral therapy, systematic behavioral family therapy, and nondirective supportive therapy. While most participants in this study eventually recovered, those with severe depression and self-perceived parent-child conflict are at greater risk for chronic depression and recurrences.

Development of topography within song control circuitry of zebra finches during the sensitive period for song learning

Refinement of topographic maps during sensitive periods of development is a characteristic feature of diverse sensory and motor circuits in the nervous system. Within the neural system that controls vocal learning and behavior in zebra finches, axonal connections of the cortical nucleus lMAN demonstrate striking functional and morphological changes during vocal development in juvenile males. These circuits are uniquely important for song production during the sensitive period for vocal learning, and the overall size of these brain regions and their patterns of axonal connectivity undergo dramatic growth and regression during this time. Axonal connections to and from lMAN are topographically organized in adult males that have already learned song. We wondered whether the large-scale changes seen in lMAN circuitry during the time that vocal behavior is being learned and refined could be accompanied by the emergence of topographic mapping. However, results presented herein demonstrate that most of these song-control circuits show the same broad patterns of axonal connectivity between subregions of individual nuclei at the onset of song learning as seen in adult birds. Thus, coarse topographic organization is not dependent on the types of experience that are crucial for vocal learning. Furthermore, this maintenance of topographic organization throughout the period of song learning is clearly not achieved by maintenance of static axonal arbors. In fact, because the volumes of song-control nuclei are growing (or regressing), topography must be maintained by active remodeling of axonal arbors to adapt to the changes in overall size of postsynaptic targets. A salient exception to this pattern of conserved topography is the projection from lMAN to the motor cortical region RA: this pathway is diffusely organized at the onset of song learning but undergoes substantial refinement during early stages of song learning, suggesting that remodeling of axonal connections within this projection during the period of vocal learning may signify the production of increasingly refined vocal utterances.

Genetic susceptibility to end-stage renal disease

New methods have been developed to uncover the genotypes that result in complex diseases. End-stage renal disease is a complex disease, without a simple correspondence between genotype and phenotype. Both population-based and family-based epidemiological studies and analysis of model organisms suggest that the pathogenesis of end-stage renal disease may have a genetic component. A number of studies have analyzed candidate nephropathy genes with little success, but recently several well-designed studies of multiplex families with diabetic nephropathy have identified candidate nephropathy susceptibility loci. To date, kidney disease-oriented research has focused on effector mechanisms responsible for the initiation and progression of chronic renal disease. However, because end-stage renal disease is a complex disease, interruption of a single effector pathway is unlikely to result in significant therapeutic benefit. Further understanding of the pathogenesis of kidney disease and the development of new kidney disease therapies will require continued application of genetic and genomic tools to kidney disease research.

T cell-tropic HIV gp120 mediates CD4 and CD8 cell chemotaxis through CXCR4 independent of CD4: implications for HIV pathogenesis

HIV entry is determined by one or more chemokine receptors. T cell-tropic viruses bind CXCR4, whereas macrophage-tropic viruses use CCR5 and other CCRs. Infection with CXCR4 and CCR5-tropic HIV requires initial binding to CD4, and chemotaxis induced by the CCR5-tropic envelope has been reported to be strictly dependent on CD4 binding. We demonstrate that, in contrast to CD4-dependent gp120 signaling via CCR5, envelope signaling through CXCR4 is CD4 independent, inducing chemotaxis of both CD4 and CD8 T cells. Signaling by virus or soluble envelope through CXCR4 may affect pathogenesis by attracting and activating target and effector cells.

Characterization of neuropeptide Y-induced feeding in mice: do Y1-Y6 receptor subtypes mediate feeding?

The stimulation of food consumption after i.c.v. administration of various neuropeptide Y (NPY) receptor agonists was examined in CD-1 mice. These agonists, including endogenous peptides NPY, peptide YY (PYY), and pancreatic polypeptide, as well as several N-terminal truncated and synthetic peptides that are prototypic receptor agonists at Y1-Y6 NPY receptors ([Leu31Pro34]NPY, NPY2-36, NPY3-36, NPY13-36, PYY3-36, Pro34PYY, and D-Trp32NPY), showed varying abilities to elicit food consumption such that PYY > NPY2-36 = NPY = PYY3-36 > Pro34PYY > NPY3-36 >> [Leu31Pro34]NPY > NPY13-36 = D-Trp32NPY = pancreatic polypeptide. Published reports have suggested that NPY-induced feeding is mediated via the Y1 or the Y5 receptor subtypes. However, the relative ability of the various peptide analogs to elicit feeding differed from the relative ability of these peptides to bind to cloned Y1-Y6 receptors. The effects of prototypic Y1 receptor antagonists on NPY-induced feeding were also evaluated after i.c.v. administration. GR231118 (1229U91), a peptide Y1 antagonist, did not block NPY-induced feeding at the doses tested. BIBP3226, a nonpeptide Y1 receptor antagonist, as well as its opposite enantiomer, BIBP3435, which is inactive at Y1 receptors, blocked feeding elicited by NPY, [Leu31Pro34], or PYY at doses that did not cause overt behavioral dysfunction. The lack of effects with GR231118 and the nonstereoselective effects of BIBP3226 suggested that NPY-induced feeding in mice was not mediated via the Y1 receptor. Thus, by using currently available prototypic peptide NPY receptor agonists for Y1-Y6 receptors and peptide and nonpeptide Y1 receptor antagonists GR231118 and BIBP3226, the mediation of NPY-induced feeding cannot be unequivocally attributed to any one of the known NPY receptors. It is possible that NPY-induced feeding is mediated either by a combination of more than one NPY receptor subtype or by a unique NPY receptor subtype. Additional subtype-selective receptor antagonists, when available, will help to clarify this issue further.

Kainate GluR5 receptor subtype mediates the nociceptive response to formalin in the rat

In order to study the roles of the AMPA and kainate subtypes of non-NMDA glutamate receptors in the processing of persistent nociceptive information, compounds with varying activities at these receptors were examined for effects on the formalin-induced paw-licking behavior in rats. The selective AMPA antagonist, LY300164 and the mixed AMPA/kainate antagonist, NBQX, were compared for their effects on formalin-induced pain behavior. NBQX (3, 10, 20 mg/kg, i.p.), caused antinociception as well as ataxia whereas the selective AMPA antagonist, LY300164 (3,5,10 mg/kg, i.p.), did not cause antinociception at doses that did not produce ataxia. In view of the well documented distribution of kainate receptors on C fibres and of the kainate-preferring iGluR5 subtype on dorsal root ganglia (DRG), we tested a series of three decahydroisoquinolines with different profiles of activity between iGluR5 and AMPA receptors and all without activity on iGluR6, iGluR7 or KA2 subtypes. LY293558 (0.1, 1, 3, 5 mg/kg, i.p.), which had low micromolar affinity for both iGluR5 and 2 caused, like NBQX, both antinociceptive and ataxic effects. However, the selective iGluR5 antagonist LY382884 (5, 10, 30, 100 mg/kg, i.p.), exhibited antinociceptive actions without ataxia while the iGluR2 preferring antagonist LY302679 (5 mg/kg, i.p), caused ataxia but did not produce antinociceptive effects at that dose. These actions were stereoselective since the enantiomeric compounds, LY293559 and LY302680, were ineffective in these tests. The data strongly suggest an involvement of iGluR5 in the processing of nociceptive information.

Actin-dependent receptor colocalization required for human immunodeficiency virus entry into host cells

Human immunodeficiency virus (HIV) envelope binds CD4 and a chemokine receptor in sequence, releasing hydrophobic viral gp41 residues into the target membrane. HIV entry required actin-dependent concentration of coreceptors, which could be disrupted by cytochalasin D (CytoD) without an effect on cell viability or mitosis. Pretreatment of peripheral blood mononuclear cells, but not virus, inhibited entry and infection. Immunofluorescent confocal microscopy of activated cells revealed CD4 and CXCR4 in nonoverlapping patterns. Addition of gp120 caused polarized cocapping of both molecules with subsequent pseudopod formation, while CytoD pretreatment blocked these membrane changes completely.

The nonpeptide NK-1 receptor antagonists LY303870 and LY306740 block the responses of spinal dorsal horn neurons to substance P and to peripheral noxious stimuli

The effects of novel substance P (NK-1) receptor antagonists LY303870 and LY306740, as well as LY306155, the enantiomer of LY303870, were tested on the responses of nociceptive spinal dorsal horn neurons to iontophoretically applied substance P and to peripheral noxious stimuli. The peripheral stimuli included noxious thermal and pinch stimuli applied to the cutaneous receptive field in the hind paw and stimulation of the superficial peroneal nerve with a train of high-intensity electrical stimuli. Extracellular recordings were obtained using multi-barrel electrodes from L4-L7 segments of the spinal cord in cats anaesthetized with alpha-chloralose and spinalized at the L1 level. The antagonists were given i.v. (0.5-4.0 mg/kg). Responses to substance P were inhibited by LY303870 and by LY306740 in a dose-related manner, but were not affected by LY306155. Responses to peripheral noxious thermal stimulation were inhibited in a dose-related manner by LY303870 and LY306740, and only at higher doses (2 mg/kg or more) by LY306155. Responses to pinch stimuli were inhibited by LY303870 and LY306740. LY306155 lacked consistent effects on pinch responses. LY303870 selectively inhibited the late component of the response to electrical stimulation of the superficial peroneal nerve. When these three drugs were tested against the responses of dorsal horn neurons to the excitatory amino acid, N-methyl-D-aspartate, the responses were unaffected. These data suggest that LY303870 and LY306740 pass from the circulation into the spinal cord where they antagonize dorsal horn neuronal responses to substance P and nociceptive inputs.

5HT1A receptor antagonists enhance the functional activity of fluoxetine in a mouse model of feeding

Fluoxetine has been reported to suppress food intake in animal models of feeding. Fluoxetine increases extracellular serotonin in the brain. 5HT1A autoreceptors regulate synaptic levels of serotonin. A combination of a 5HT1A receptor antagonist and fluoxetine has been previously reported to enhance extracellular levels of serotonin over what is obtained with fluoxetine alone. Thus, a combination of fluoxetine and a 5HT1A antagonist could enhance the ability of fluoxetine to suppress appetite. Fluoxetine was tested in a model of feeding, in which CD-1 mice were trained to drink sweetened condensed milk. Fluoxetine was found to attenuate milk drinking, in a dose-dependent manner, at doses greater than 10 mg/kg, i.p. A 10 mg/kg dose of fluoxetine, which was ineffective by itself, was then combined either with 5-hydroxytryptophan (5HTP), a serotonin precursor, or with S(-) pindolol, a 5HT1A/beta adrenergic receptor antagonist or with LY206130, a more selective 5HT1A receptor antagonist. These treatment paradigms resulted in significant attenuation of the consumption of sweetened condensed milk. Since fluoxetine has been shown to be useful in the treatment of eating disorders and to promote weight loss in obese humans, although at doses greater than those required for the treatment of depression, a combination of fluoxetine with a 5HT1A receptor antagonist could be of clinical utility in the treatment of eating disorders and obesity.

Modeling neural activity using the generalized inverse Gaussian distribution

Spike trains from neurons are often used to make inferences about the underlying processes that generate the spikes. Random walks or diffusions are commonly used to model these processes; in such models, a spike corresponds to the first passage of the diffusion to a boundary, or firing threshold. An important first step in such a study is to fit families of densities to the trains' interspike interval histograms; the estimated parameters, and the families' goodness of fit can then provide information about the process leading to the spikes. In this paper, we propose the generalized inverse Gaussian family because its members arise as first passage time distributions of certain diffusions to a constant boundary. We provide some theoretical support for the use of these diffusions in neural firing models. We compare this family with the lognormal family, using spike trains from retinal ganglion cells of goldfish, and simulations from an integrate-and-fire and a dynamical model for generating spikes. We show that the generalized inverse Gaussian family is closer to the true model in all these cases.

A clinical psychotherapy trial for adolescent depression comparing cognitive, family, and supportive therapy

BACKGROUND

Previous studies in nonclinical samples have shown psychosocial treatments to be efficacious in the treatment of adolescent depression, but few psychotherapy treatment studies have been conducted in clinically referred, depressed adolescents.

METHODS

One hundred seven adolescent patients with DSM-III-R major depressive disorder (MDD) were randomly assigned to 1 of 3 treatments: individual cognitive behavior therapy, systemic behavior family therapy (SBFT), or individual nondirective supportive therapy (NST). Treatments were 12 to 16 sessions provided in as many weeks. Intent-to-treat analyses were conducted using all follow-up data.

RESULTS

Of the 107 patients enrolled in the study, 78 (72.9%) completed the study, 4 (3.7%) never initiated treatment, 10 (9.3%) had exclusionary criteria that were undetected at entry, 8 (7.5%) dropped out, and 7 (6.5%) were removed for clinical reasons. Cognitive behavior therapy showed a lower rate of MDD at the end of treatment compared with NST (17.1% vs 42.4%; P = .02), and resulted in a higher rate of remission (64.7%, defined as absence of MDD and at least 3 consecutive Beck Depression Inventory scores < 9) than SBFT (37.9%; P = .03) or NST (39.4%; p = .04). Cognitive behavior therapy resulted in more rapid relief in interviewer-rated (vs both treatments, P = .03) and self-reported depression (vs SBFT, P = .02). All 3 treatments showed significant and similar reductions in suicidality and functional impairment. Parents' views of the credibility of cognitive behavior therapy improved compared with parents' views of both SBFT (P = .01) and NST (P = .05).

CONCLUSIONS

Cognitive behavior therapy is more efficacious than SBFT or NST for adolescent MDD in clinical settings, resulting in more rapid and complete treatment response.

The rabbit ileum: a sensitive and selective preparation for the neuropeptide Y Y5 receptor

The rabbit ileum shows high sensitivity to neuropeptide Y. Relaxations are obtained in this tissue with human pancreatic polypeptide > peptide YY > > [Leu31,Pro34]neuropeptide Y > rat pancreatic polypeptide > human neuropeptide Y in this order of potency that is indicative of a Y5 receptor. Effects of neuropeptide Y and congeners are not affected by neuropeptide Y Y1 receptor antagonist (BIBP 3226), but are reduced by the neuropeptide Y Y5 receptor antagonist JCF 104 (2-(naphtalen-1-yl)-3-phenylpropane-1,2-diamine). Rabbit ilea provide sensitive and selective neuropeptide Y Y5 receptor preparations.

Homozygosity by descent for a rare mutation in the myophosphorylase gene is associated with variable phenotypes in a Druze family with McArdle disease

We examined a large consanguineous Druze family with McArdle disease for mutations in the glycogen myophosphorylase (PYGM) gene. All affected subjects were autozygous for a single G to A transition that abolishes the 5' consensus splice site in the first nucleotide of intron 14. The G to A transition is a rare mutation, with only one previous report in a single white subject heterozygous for this mutation and another, more common, mutation at codon 49. The kindred in our study is the first family reported in which disease is caused by homozygosity for this rare mutation. This kindred was originally reported as the first familial case of McArdle disease in the Druze.

LY303870, a centrally active neurokinin-1 antagonist with a long duration of action

The selective neurokinin (NK)-1 antagonist LY303870 has high affinity and specificity for human and guinea pig brain NK-1 receptors labeled with 125I-substance P. It has approximately 15- to 30-fold lower affinity for rat and mouse brain NK-1 receptors, consistent with previously reported species differences in the affinities of nonpeptide antagonists for NK-1 receptors. In vivo, LY303870 blocked the characteristic, caudally directed, biting and scratching response elicited by intrathecal administration of the selective NK-1 agonist Ac-[Arg6,Sar9,Met(O2)11]substance P6-11 in conscious mice. The potentiation of the tail-flick response elicited by intrathecal administration of the NK-1 agonist [Sar9,Met(O2)11]substance P in rats was also selectively blocked by LY303870. When tested in a model of persistent nociceptive activation induced by tissue injury (the formalin test), LY303870 blocked licking behavior in the late phase of the formalin test, in a dose-dependent manner. After oral administration of 10 mg/kg, the blockade of the late-phase licking behavior was evident for at least 24 hr. Ex vivo binding studies in guinea pigs showed that orally administered LY303870 potently inhibited binding to central and peripheral NK-1 receptors labeled with 125I-substance P. This inhibition was long-lasting, consistent with other in vivo activities. LY306155, the opposite enantiomer of LY303870, was less active in all of the functional assays. In rodents, LY303870 did not exhibit any neurological, motor, cardiovascular, gastrointestinal or autonomic side effects at doses of < or = 50 mg/kg p.o. Thus, LY303870 is a potent, centrally active, NK-1 antagonist in vivo, with long-lasting oral activity.

Mitochondrial versus nuclear admixture estimates demonstrate a past history of directional mating

Six blood group antigens (ABO, RH, MNS, KK, KP, FY) and five plasma proteins (HP, GC, APOA4, FXIIIB, C1R) were typed in 790 individuals, and 12 mtDNA RFLP and deletion polymorphisms were typed in 657 individuals from the San Luis Valley, Colorado. The 790 nuclear typings were conducted on 399 Anglos and 391 Hispanics, while the 657 mitochondrial haplotypes were generated from 207 Anglos and 450 Hispanics. Chakraborty's ADMIX2 FORTRAN program was used to estimate the average Amerindian admixture using all nuclear loci simultaneously. Since there is no recombination in mtDNA, the sum of the frequencies of the Amerindian/Asian-specific mitochondrial haplotypes represents the level of Amerindian admixture. The nuclear estimates of Amerindian admixture were 33.15 +/- 2.41% for the Hispanics and 9.72 +/- 1.90% for the Anglos, while the strictly maternally inherited mtDNA estimates of Amerindian admixture were 85.11% for the Hispanics and 0.97% for the Anglos. This dramatic difference in estimated levels of admixture between the biparentally derived nuclear estimates and the uniparentally derived mtDNA estimates is indicative of past directional matings between Hispanic males and Amerindian females.

Improving the design of muscle relaxant studies. Stabilization period and tetanic recruitment

BACKGROUND

The results from studies of muscle relaxants show wide variations among institutions. The authors hypothesized that some of this variability could be explained by differences in duration of nerve stimulation before drug administration (stabilization period).

METHODS

Train-of-four stimulation was applied every 12 s to both ulnar nerves and adductor pollicis twitch tension was measured in anesthetized participants given 30 micrograms/kg vecuronium. In phase 1, the stabilization period was > 30 min for both extremities. In phase 2-4, stabilization period was 20 min for one extremity and 2 min for the other. In addition, in phase 3, a 2-s 50-Hz tetanus initiated the 2-min stimulation period; in phase 4, duration of tetanus was 5 s. Twitch recovery was recorded until stable for more than 15 min. Time to 25% recovery (clinical duration) was calculated based on two indices: predrug and final (recovery) twitch tension. Values for onset and clinical duration were compared by paired parametric and nonparametric tests.

RESULTS

In phase 1, predrug and recovery twitch tension were similar in each extremity, and onset and clinical duration did not differ between extremities, permitting paired comparisons in remaining studies. In phase 2, onset was more rapid with 20-min of prestimulation. With 20-min prestimulation, predrug and recovery twitch tension were similar; with 2-min prestimulation, recovery twitch tension exceeded predrug values. When referenced to predrug twitch tension, clinical duration was shorter with 2-min, that with 20-min prestimulation. Initiating stimulation with 2-s or 5-s 50-Hz tetani (phases 3, 4) abolished differences between extremities in onset and recovery.

CONCLUSIONS

With only train-of-four stimulation (no tetani), onset and clinical duration vary with duration of prestimulation, suggesting that a brief period of predrug stimulation is inadequate. However, lengthy prestimulation may be impractical in clinical studies. Tetanic stimulation for 2 or 5 s obviates the need for prolonged stabilization during studies of muscle relaxants.

Peripheral effects of three novel non-peptide tachykinin NK1 receptor antagonists in the anaesthetized rat

Three novel non-peptide tachykinin NK1 receptor antagonists were assessed on the transient fall in mean arterial blood pressure and the salivation induced by i.v. substance P (0.65 nmol/kg) in the urethane-anaesthetized rat. LY303241 ((R)-1-[N-(2-methoxybenzyl)acetylamino]-3-(1H-indol-3-yl)-2-[N-(2-(4- phenylpiperazin-1-yl)acetyl)amino]propane), LY303870 ((R)-1-[N-(2-methoxybenzyl)acetylamino]-3-(1H-indol-3-yl)-2-[N-(2-(4-(++ +piperidin-1 -yl)piperidin-1-yl)acetyl)amino]propane) and LY306740 ((R)-1-[N-(2-methoxybenzyl)acetylamino]-3-(1H-indol-3-yl)-2-[N-(2-(4 -cyclohexylpiperazin-1-yl)acetyl)amino]propane) (65 nmol-9 micromol/kg i.v.; 5 min earlier) inhibited both the vasodepressor and salivary responses to substance P in a dose-dependent manner. LY303241 and LY306740 were more potent in inhibiting the vascular response to substance P while LY303870 was more potent in inhibiting the salivary response. LY303870 and LY306740 were devoid of direct effects while LY303241 decreased blood pressure and heart rate for 1 and 10 min, respectively. The antagonists act in a stereoselective and specific manner since the opposite (S) enantiomers of LY303870 (LY306155) and LY306740 (LY307679) failed to block the effects of substance P. In addition, LY303241, LY303870 and LY306740 neither affected the hypotension and the salivation induced by carbachol nor the increases in mean arterial pressure and heart rate induced by the tachykinin NK2 receptor agonist [beta-Ala8]neurokinin A-(4-10). Only LY303241 attenuated the decreases in mean arterial pressure and heart rate evoked by the tachykinin NK3 receptor agonist senktide. LY303870 and LY306740 appear to be the most interesting antagonists since they act in a specific and selective manner at the tachykinin NK1 receptor. The difference in the order of potency of the three antagonists to inhibit the hypotension and salivation elicited by substance P could be ascribed to their pharmacodynamic features or to the existence of different signal transduction mechanisms or receptor subtypes.

Bayesian inference on prevalence using a missing-data approach with simulation-based techniques: applications to HIV screening

Health departments and other health-related authorities seek accurate assessment of the spread of human immunodeficiency virus (HIV) among populations. Although screening for HIV provides a direct means for estimating its prevalence, it is complicated by the heterogeneity of available diagnostic tests and the degree to which they can diagnose HIV accurately. To integrate the limited precision of screening tests with prior results, Bayesian inference becomes a method of choice. Current Bayesian methods, however, have limited applications and do not readily generalize for complicated sampling designs and for modelling needs, particularly those that relate to HIV screening. By utilizing recent developments in the theories of missing-data analysis and simulation-based techniques, we develop an approach to Bayesian analysis of prevalence. This methodology is quite general for a variety of sampling schemes and sufficiently flexible to accommodate various practical considerations that arise from HIV screening. We illustrate the methodology with real as well as simulated data sets. Further, by utilizing the methodology, we performed simulations to demonstrate that pooled testing provides a cost-effective means to improve the precision of estimates of prevalence under the currently limited screening technology.

Early presentation of metastatic medullary carcinoma in multiple endocrine neoplasia, type IIA: implications for therapy

A girl 5 years 11 months of age, belonging to an extensive kindred with multiple endocrine neoplasia, type IIA (MEN IIA), was found to have multifocal medullary thyroid carcinoma with metastasis in one paraglandular lymph node after positive findings on a calcium-pentagastrin stimulation test. Her sister, 3 years 8 months of age, also had an elevated calcitonin level, and thyroidectomy revealed C-cell hyperplasia and a focus of medullary thyroid carcinoma. These two cases underscore the need for prophylactic thyroidectomies in MEN IIA patients as young as 5 years of age and strict yearly provocative screening beginning at age 1 year.

A randomized, controlled trial of amitriptyline in the acute treatment of adolescent major depression

OBJECTIVE

To determine amitriptyline's (AMI) efficacy in the acute treatment of adolescent major depressive disorder (MDD).

METHOD

Subjects aged 12 through 17 years meeting Research Diagnostic Criteria for MDD, diagnosed with the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS), participated in a 2-week placebo-washout followed by an 8-week, randomized, double-blind, parallel-design, placebo-controlled trial of AMI, 5 mg/kg per day. The K-SADS nine-item scale, the Hamilton Depression Rating Scale, and the Clinical Global Impressions rating scale were used as outcome measures.

RESULTS

Thirty-one subjects were randomized (18 AMI, 13 placebo). Twenty-two subjects were study completers (12 AMI, 10 placebo). AMI's efficacy was suggested by the Clinical Global Impressions but not the K-SADS-derived data. Perhaps the primary limitation of the current study is its small sample size.

CONCLUSION

No definitive recommendation can be made regarding the efficacy of tricyclic antidepressants in the treatment of adolescent MDD.

Psychiatric disorder and metabolic control among youths with IDDM. A longitudinal study

OBJECTIVE

To investigate the longitudinal relationship between psychiatric diagnostic variables and metabolic control among youths with IDDM.

RESEARCH DESIGN AND METHODS

A group of 88 youths, 8 to 13 years old at onset of IDDM, were evaluated repeatedly during a 9-year follow-up period, on average, using a standardized psychiatric protocol. Levels of HbA1 were also assessed repeatedly. Psychiatric diagnoses were derived independently of HbA1 values.

RESULTS

In univariate longitudinal analyses, the psychiatric diagnosis of noncompliance with medical treatment was significantly related to HbA1 level. There was a trend of an association between any major psychiatric disorder, as well as nondepressive disorder, and HbA1. Interaction terms between IDDM duration (or age) and psychiatric variables were also significantly related to metabolic control. According to the final multivariate model of repeatedly assessed HbA1, noncompliance with medical treatment (irrespective of IDDM duration) and the interaction between nondepressive psychiatric disorder and IDDM duration contributed to worse metabolic control.

CONCLUSIONS

We found some support for the hypothesis that psychiatric morbidity negatively affects blood glucose regulation and that its consequences are more marked the longer young patients have had IDDM. We did not confirm the hypothesis that depressive illness has particularly deleterious consequences on metabolic control. Noncompliance with medical treatment and having had nondepressive psychiatric illness in interaction with IDDM duration account for a statistically significant but clinically modest amount of variability in HbA1 over time. The weak relationship among these variables may explain the inconsistent findings in the literature regarding psychiatric morbidity and metabolic control.