Social media engagement amongst 2017 colorectal surgery Tripartite Meeting attendees: updates on contemporary social media use

AIM

Engagement by medical professionals with social media (SM) is increasing. Variation is noted in engagement between SM platforms and between surgical specialities and geographical regions. We aimed to study SM engagement by colorectal surgeons attending an international conference.

METHOD

Surgeons were identified from the delegate list of the 2017 Annual Meeting of the American Society of Colon and Rectal Surgeons (ASCRS) and Tripartite Meeting (Seattle, Washington, USA). Delegates were searched on Twitter and LinkedIn for the presence of a matching profile. SM presence, activity, gender and geographical region were analysed.

RESULTS

Two hundred and seventy (13.2%) surgeons had Twitter accounts and 994 (44.3%) had LinkedIn profiles. UK surgeons were more likely to be on Twitter than surgeons from elsewhere (23.4% vs 12.7%, P = 0.0072). Significant variation in SM membership between each geographical region was noted, with usage rates for Twitter of 18.1% in Europe, 14.4% in North America, 12.9% in South America, 4.3% in Oceania, 3.7% in Asia and 0% in Africa. A similar picture for LinkedIn is seen. The #ASCRS17 meeting saw the highest participation of users to date (979 participants, over 7000 individual tweets and nearly 14 million impressions).

CONCLUSION

SM engagement by colorectal surgeons continues to increase. Significant geographical variation is noted, suggesting that SM's unique potential for education and networking may not yet be widely appreciated globally. Future work should include further analysis into tweet contents to gain insights and optimize the use of SM as an educational adjunct.

Contemporary engagement with social media amongst hernia surgery specialists

PURPOSE

Healthcare professional engagement is increasing. This study aims to identify levels of adoption and engagement of several social media platforms by a large international cohort of hernia surgery specialists.

METHODS

Hernia specialists attending the 38th International Congress of the European Hernia Society were identified. A manual search was then performed on Twitter, ResearchGate, and LinkedIn to identify those who had named accounts. Where accounts were identified, data on markers of utilisation were assessed.

RESULTS

759 surgeons (88.5% male) from 57 countries were identified. 334 surgeons (44%) engaged with a social media platform. 39 (5.1%) had Twitter accounts, 189 (24.9%) had ResearchGate accounts and 265 (34.9%) had LinkedIn accounts. 137 surgeons (18.1%) had accounts on 2 or more social media platforms. There was no gender association with social media account ownership (p > 0.05). Engagement in one social media platform was associated with increased engagement and utilisation on other platforms; LinkedIn users were more likely to have Twitter accounts (p < 0.001) and ResearchGate profiles (p < 0.001). Surgeons on all three SM platforms were more likely to have high markers of engagement across all SM platforms (multiple outcomes, p < 0.05). Geographical variation was noted with UK and South American Surgeons being more likely to be present on Twitter than their counterparts (p = 0.031).

CONCLUSIONS

The level of engagement with social media amongst Hernia surgeons is similar to other surgical specialities. Geographical variation in SM engagement is seen. Engagement with one SM platform is associated with presence on multiple platforms.

In vitro Sequential Selection and Characterization of Human Immunodeficiency Virus Type 1 Variants with Reduced Sensitivity to Hydroxyethylurea Protease Inhibitors

In vitro resistance to the human immunodeficiency virus (HIV) protease inhibitors SC-52151 and SC-55389A was evaluated in an in vitro sequential selection scheme. HIVRF variants were selected for reduced sensitivity to SC-52151 and subsequently passaged in both SC-52151 and a structurally different hydroxyethylurea protease inhibitor, SC-55389A, to select for dual-resistant virus. SC-52151 selection alone resulted in a 23-fold reduction in virus sensitivity whereas selection in both inhibitors resulted in 34- and eightfold reductions in virus sensitivity to SC-52151 and SC-55389A, respectively. Sequence analysis of the protease gene revealed that SC-52151 -resistant virus had a Gly to Val substitution at residue 48 (G48V) and, in 58% of subclones, an accompanying Val to Ala substitution at residue 82 (V82A). Dual-resistant virus had both G48V and V82A substitutions present and, in the majority of subclones, an lle to Thr and/or Leu to Pro substitution at residues 54 and 63, respectively. Drug susceptibility assays with limiting dilution-cloned HIVRFR (G48V/V82A) and HIVRFRR (G48V/154T/L63P/V82A) viruses demonstrated moderate to high-level cross-resistance to additional structurally non-related protease inhibitors. Recombinant HIVHXB2 proviral clones with G48V, L63P and V82A substitutions showed that one active site mutation was permissible, but the presence of both G48V and V82A substitutions together significantly reduced infectious virus production. Insight into the contributions of the observed substitutions to drug resistance is presented in molecular modelling studies.

Contemporary use of social media by consultant colorectal surgeons

AIM

There is evidence of significant growth in the engagement of UK health-care professionals with 'open' social media platforms, such as Twitter and LinkedIn. Social media communication provides many opportunities and benefits for medical education and interaction with patients and colleagues. This study was undertaken to evaluate the uptake of public social media membership and the characteristics of use of such media channels amongst contemporary UK consultant colorectal surgeons.

METHOD

Colorectal surgeons were identified from the Association of Coloproctology of Great Britain and Ireland (ACPGBI) national registry of colorectal mortality outcomes and were cross-referenced with the General Medical Council (GMC) register. Individuals were identified by manual searching on a number of social media platforms. Matching accounts were then examined to confirm ownership and to evaluate key markers of use.

RESULTS

Six-hundred and eighteen individual consultant colorectal surgeons from 142 health authorities were studied (79.5% were ACPGBI members and 90.8% were male). Two-hundred and twenty-nine (37.1%) had LinkedIn profiles (37.7% male surgeons, 29.8% female surgeons; P = 0.2530). LinkedIn membership was significantly higher in ACPGBI members (P < 0.001) and in those with GMC registration before 1997 vs after this date (39% before 1997 vs 30% after 1997; P = 0.03). LinkedIn members had a mean of 62 connections (median = 22), and 19 (3.1%) surgeons had Twitter profiles with a mean of 82 (median = 16; range: 0-914) followers and their accounts were followed by a mean of 87 (median = 27; range: 0-642) persons.

CONCLUSION

UK consultant colorectal surgeons are less engaged with social media than reported studies from other health-care professional groups. Further education and appropriate guidance on usage may encourage uptake and confidence, particularly in younger consultants.

Effects of spatial congruity on audio-visual multimodal integration

Spatial constraints on multisensory integration of auditory (A) and visual (V) stimuli were investigated in humans using behavioral and electrophysiological measures. The aim was to find out whether cross-modal interactions between A and V stimuli depend on their spatial congruity, as has been found for multisensory neurons in animal studies (Stein & Meredith, 1993). Randomized sequences of unimodal (A or V) and simultaneous bimodal (AV) stimuli were presented to right- or left-field locations while subjects made speeded responses to infrequent targets of greater intensity that occurred in either or both modalities. Behavioral responses to the bimodal stimuli were faster and more accurate than to the unimodal stimuli for both same-location and different-location AV pairings. The neural basis of this cross-modal facilitation was studied by comparing event-related potentials (ERPs) to the bimodal AV stimuli with the summed ERPs to the unimodal A and V stimuli. These comparisons revealed neural interactions localized to the ventral occipito-temporal cortex (at 190 msec) and to the superior temporal cortical areas (at 260 msec) for both same- and different-location AV pairings. In contrast, ERP interactions that differed according to spatial congruity included a phase and amplitude modulation of visual-evoked activity localized to the ventral occipito-temporal cortex at 100-400 msec and an amplitude modulation of activity localized to the superior temporal region at 260-280 msec. These results demonstrate overlapping but distinctive patterns of multisensory integration for spatially congruent and incongruent AV stimuli.

An analysis of audio-visual crossmodal integration by means of event-related potential (ERP) recordings

Crossmodal integration was studied in humans by presenting random sequences of auditory (brief noise bursts), visual (flashes), and audiovisual (simultaneous noise bursts and flashes) stimuli from a central location at irregular intervals between 600 and 800 ms. The subjects' task was to press a button to infrequent and unpredictable (P=0.15) target stimuli that could be either a more intense noise burst, a brighter flash, or a combination of the two. In accordance with previous studies, behavioral data showed that bimodal target stimuli were responded to much faster and were identified more accurately than the unimodal target stimuli. The neural basis of this crossmodal interaction was investigated by subtracting the ERPs to the auditory (A) and the visual (V) stimuli alone from the ERP to the combined audiovisual (AV) stimuli (i.e. interaction=AV-(A+V)). Using this approach, we replicated previous reports of both early (at around 40 ms) and late (after 100 ms) ERP interaction effects. However, it appears that the very early interaction effects can be largely accounted for by an anticipatory ERP that precedes both the unimodal and bimodal stimuli. In calculating the ERP interaction this slow shift is subtracted twice, resulting in an apparent shift of the opposite polarity that may be confounded with actual crossmodal interactions.

Transient spatial attention modulates distinct components of the auditory ERP

We recorded ERPs to pairs of externally presented tones, T1 and T2, in the absence of attentional cues to determine whether attention is momentarily sustained at the location of a behaviourally relevant sound, and what effect this focusing of attention might have on the neural response to target stimuli. ERPs to T2 were more negative when the preceding T1 was presented on the same side of fixation than when T1 was presented on the opposite side of fixation. This negative difference consisted of an early, parietal phase and a later, frontocentral phase. These results confirm and extend previously reported effects of transient spatial attention on auditory ERPs, and they demonstrate that transient spatial attention has a distinct and robust effect on the early stages of stimulus processing in the auditory system.

Selective, orally active MMP inhibitors with an aryl backbone

This letter describes SAR exploration and rat PK optimization of a series of novel, MMP-1 sparing aryl hydroxamate sulfonamides with activity against MMP-2 and MMP-13.

Electrophysiological evidence for the "missing link" in crossmodal attention

Orienting attention involuntarily to the location of a sensory event influences responses to subsequent stimuli that appear in different modalities with one possible exception: orienting attention involuntarily to a sudden light sometimes fails to affect responses to subsequent sounds (e.g., Spence & Driver, 1997). Here we investigated the effects of involuntary attention to a brief flash on the processing of subsequent sounds in a design that eliminates stimulus-response compatibility effects and criterion shifts as confounding factors. In addition, the neural processes mediating crossmodal attention were studied by recording event-related brain potentials. Our data show that orienting attention to the location of a spatially nonpredictive visual cue modulates behavioural and neural responses to subsequent auditory targets when the stimulus onset asynchrony is short (between 100 and 300 ms). These findings are consistent with the hypothesis that involuntary shifts of attention are controlled by supramodal brain mechanisms rather than by modality-specific ones.

Mental disabilities under the ADA: a management rights approach

While numerous sources have focused on employee rights and employer obligations under the Americans with Disabilities Act, this article will emphasize employer rights with respect to mental disabilities under the ADA. Specifically, it addresses the ADA's definition of "mental disability," the right of employers to screen job applicants in spite of the ADA, the conditions under which an employer may require an employee to undergo a "fitness for duty" examination, and the limits of the duty to "reasonably accommodate" an employee with a mental disability.

EEOC guidance on psychiatric disabilities: many problems, few workable solutions

The EEOC recently issued "Enforcement Guidance" on psychiatric disabilities under the Americans with Disabilities Act. Although the Guidance provides clarification of a few issues involving mental disabilities under the ADA, in most respects the Guidance is problematic. For example, the Guidance suggests that the inability to get along with a supervisor or coworkers may constitute a disability under the ADA, that an employer may have to "accommodate" a disabled employee's misconduct, that an employer cannot require an employee to follow doctor's orders as a condition of employment, and that an employer may be obligated to modify work rules and procedures to accommodate a mentally disabled employee but is prohibited from explaining to coworkers why it is making such modifications. As the EEOC's Guidance exceeds or conflicts with the ADA in some respects and is largely unworkable in many respects, it remains to be seen how many courts will actually follow it.

Synthesis and activity of selective MMP inhibitors with an aryl backbone

A series of novel, MMP-1 sparing arylhydroxamate sulfonamides with activity against MMP-2 and -13 is described.

Involuntary orienting to sound improves visual perception

To perceive real-world objects and events, we need to integrate several stimulus features belonging to different sensory modalities. Although the neural mechanisms and behavioural consequences of intersensory integration have been extensively studied, the processes that enable us to pay attention to multimodal objects are still poorly understood. An important question is whether a stimulus in one sensory modality automatically attracts attention to spatially coincident stimuli that appear subsequently in other modalities, thereby enhancing their perceptual salience. The occurrence of an irrelevant sound does facilitate motor responses to a subsequent light appearing nearby. However, because participants in previous studies made speeded responses rather than psychophysical judgements, it remains unclear whether involuntary auditory attention actually affects the perceptibility of visual stimuli as opposed to postperceptual decision and response processes. Here we provide psychophysical evidence that a sudden sound improves the detectability of a subsequent flash appearing at the same location. These data show that the involuntary orienting of attention to sound enhances early perceptual processing of visual stimuli.

On asymmetries in cross-modal spatial attention orienting

In a previous study, Ward (1994) reported that spatially uninformative visual cues orient auditory attention but that spatially uninformative auditory cues fail to orient visual attention. This cross-modal asymmetry is consistent with other intersensory perceptual phenomena that are dominated by the visual modality (e.g., ventriloquism). However, Spence and Driver (1997) found exactly the opposite asymmetry under different experimental conditions and with a different task. In spite of the several differences between the two studies, Spence and Driver (see also Driver & Spence, 1998) argued that Ward's findings might have arisen from response-priming effects, and that the cross-modal asymmetry they themselves reported, in which auditory cues affect responses to visual targets but not vice versa, is in fact the correct result. The present study investigated cross-modal interactions in stimulus-driven spatial attention orienting under Ward's complex cue environment conditions using an experimental procedure that eliminates response-priming artifacts. The results demonstrate that the cross-modal asymmetry reported by Ward (1994) does occur when the cue environment is complex. We argue that strategic effects in cross-modal stimulus-driven orienting of attention are responsible for the opposite asymmetries found by Ward and by Spence and Driver (1997).

Involuntary listening aids seeing: evidence from human electrophysiology

It is well known that sensory events of one modality can influence judgments of sensory events in other modalities. For example, people respond more quickly to a target appearing at the location of a previous cue than to a target appearing at another location, even when the two stimuli are from different modalities. Such cross-modal interactions suggest that involuntary spatial attention mechanisms are not entirely modality-specific. In the present study, event-related brain potentials (ERPs) were recorded to elucidate the neural basis and timing of involuntary, cross-modal spatial attention effects. We found that orienting spatial attention to an irrelevant sound modulates the ERP to a subsequent visual target over modality-specific, extrastriate visual cortex, but only after the initial stages of sensory processing are completed. These findings are consistent with the proposal that involuntary spatial attention orienting to auditory and visual stimuli involves shared, or at least linked, brain mechanisms.

Semantic and affective processing in psychopaths: an event-related potential (ERP) study

We tested the hypothesis that psychopathy is associated with abnormal processing of semantic and affective verbal information. In Task 1, a lexical decision task, and in Task 2, a word identification task, participants responded faster to concrete than to abstract words. In Task 2, psychopaths made more errors identifying abstract words than concrete words. In Task 3, a word identification task, participants responded faster to positive than to negative words. In all three tasks, nonpsychopaths showed the expected event-related potential (ERP) differentiation between word stimuli, whereas psychopaths did not. In each task, the ERPs of the psychopaths included a large centrofrontal negative-going wave (N350); this wave was absent or very small in the nonpsychopaths. The interpretation and significance of these differences are discussed.

An event-related brain potential study of inhibition of return

Event-related brain potentials (ERPs) were recorded during two spatial-cuing experiments using nonpredictive cues. Our primary goal was to determine the electrophysiological consequences of inhibition of return (IOR). At long (> 500 msec) cue-target intervals, subjects responded more slowly to targets that appeared at or near the cued location, relative to targets that appeared on the opposite side of fixation from the cue. This behavioral IOR effect was associated with cue-validity effects on several components of the target-elicited ERP waveforms. The earliest such effect was a smaller occipital P1 on valid-cue trials, which we interpret as a P1 reduction. The P2 component was also smaller on valid-cue trials, indicating that nonpredictive spatial cues influence multiple stages of information processing at long cue-target intervals. Both of these effects were observed when sensory interactions between cue and target were likely to be negligible, indicating that they were not caused by sensory refractoriness. A different effect of cue validity, the posterior negative difference, was found when sensory interactions were likely to be greatest, indicating that it could arise from sensory refractoriness.

Synthesis and identification of conformationally constrained selective MMP inhibitors

We have discovered a new series of potent conformationally constrained MMP Inhibitors that are selective for MMP-13 over MMP-1.

Reduced P300 responses in criminal psychopaths during a visual oddball task

BACKGROUND

Clinicians have long recognized that psychopaths show deficits in cognitive function, but there have been few experimental studies exploring these deficits. We present here the first in a series of event-related potential (ERP) experiments designed to elucidate and characterize the neural correlates of cognitive processes of psychopaths.

METHODS

We recorded ERPs from a topographic array from 11 psychopathic and 10 nonpsychopathic prison inmates, assessed with the Hare Psychopathy Checklist-Revised, during performance of a visual oddball task. ERPs to target (25% of trials) and nontarget (75% of trials) visual stimuli were analyzed.

RESULTS

Consistent with previous research, there were no group differences in the latency or amplitude of the ERPs for the nontarget stimuli. For nonpsychopaths, the P300 amplitude was larger when elicited by the target stimuli than when elicited by the nontarget stimuli. In contrast, psychopaths failed to show reliable P300 amplitude differences between the target and nontarget conditions. Psychopaths had a smaller amplitude P300 to target stimuli than did nonpsychopaths. In addition, the amplitude of the P300 was less lateralized in psychopaths than in nonpsychopaths. Psychopaths also had a larger centrofrontal negative wave (N550) during the target condition than did nonpsychopaths.

CONCLUSIONS

The results of this study indicate that there are substantial differences between psychopaths and others in the processing of even simple cognitive tasks and provide support for information processing models of psychopathy.

Discovery of a novel series of selective MMP inhibitors: identification of the gamma-sulfone-thiols

We have discovered a new series of potent MMP Inhibitors that are selective for MMP-13 over MMP-1 incorporating a gamma-sulfone thiol.

Forensic aspects of sexual harassment

Sexual harassment law presents a complex set of issues not only for lawyers but also for psychiatrists in their roles both as evaluators and clinicians. Judge Reinhardt of the US Court of Appeals for the 9th Circuit, summed up these complexities: "We tend these days, far more than in earlier times, to find our friends, lovers, and even mates in the workplace. We ... often discover that our interests and values are closer to those of our colleagues or fellow employees than to those of people we meet in connection with other activities. In short, increased proximity breeds increased volitional sexual activity." On the other hand, he notes that Title VII "entitles individuals to a workplace that is free from the evil of sexual intimidation or repression. It is frequently difficult to reconcile the two competing values." He goes on to ask, "When does a healthy constructive interest in romance become sexual harassment? To what extent is pursuit of a co-worker proper but of a subordinate forbidden? Is wooing or courting a thing of the past? Must a suitor cease his attentions at the first sign of disinterest or resistance? Must there be an express agreement before the person seeking romance may even hold the hand of the subject of his affection? Is it now verboten to steal a kiss? In the workplace? Everywhere? Under all circumstances or only some? Has the art of romantic persuasion lost its charm? Questions relating to love and sex are among the most difficult for society to answer." The US Supreme Court has stressed the need for common sense in evaluating cases of sexual harassment. Perhaps psychiatrists can play a sobering role in developing answers to these questions.

A mutation in human immunodeficiency virus type 1 protease at position 88, located outside the active site, confers resistance to the hydroxyethylurea inhibitor SC-55389A

The hydroxyethylurea human immunodeficiency virus type 1 (HIV-1) protease inhibitors SC-55389A and SC-52151 were used to select drug-resistant variants in vitro. One clinical HIV-1 strain (89-959) and one laboratory HIV-1 strain (LAI) were passaged in peripheral blood mononuclear cells or CEMT4 cells in the presence of SC-55389A. Resistant isolates from both strains consistently had a mutation to serine for asparagine at amino acid 88 (N88S) in the protease gene either alone or in combination with a change to phenylalanine at position 10. The N88S mutation, recreated by oligonucleotide-mediated site-directed mutagenesis in HXB2, was sufficient to confer resistance to SC-55389A. In contrast, SC-52151-resistant variants selected from the monocytotropic strain SF162 had multiple substitutions in the protease gene (I11V, M461, F53L, A71V, and N88D), and the N88D mutation, re-created by oligonucleotide-mediated site-directed mutagenesis in HXB2, did not confer resistance to SC-52151. The potencies of L735,524 and Ro31-8959 were not reduced when these compounds were assayed against variants with either the N88S or N88D substitution. Position 88 is in a helix that lies behind the substrate binding pocket and may indirectly influence inhibitor binding through interactions with the amino acid at position 31. The selected mutations were persistent in the viral populations after more than 20 passages in the absence of drugs. Passaging of virus first in SC-55389A alone and then in combination with SC-52151 resulted in the accumulation of more mutations in the protease gene (L10F, D35E, D37M, I47V, 154L, A71V, V82I, and S88D) and in the selection of a variant that was cross-resistant to multiple protease inhibitors. These results indicate that a mutation in the HIV-1 protease at a position that is located outside of the substrate binding pocket confers resistance to a protease inhibitor and that mutations in the protease gene accumulate with increasing selection pressure and can persist in the absence of selection pressure.

Structural basis for selective inhibition of cyclooxygenase-2 by anti-inflammatory agents

Prostaglandins and glucocorticoids are potent mediators of inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) exert their effects by inhibition of prostaglandin production. The pharmacological target of NSAIDs is cyclooxygenase (COX, also known as PGH synthase), which catalyses the first committed step in arachidonic-acid metabolism. Two isoforms of the membrane protein COX are known: COX-1, which is constitutively expressed in most tissues, is responsible for the physiological production of prostaglandins; and COX-2, which is induced by cytokines, mitogens and endotoxins in inflammatory cells, is responsible for the elevated production of prostaglandins during inflammation. The structure of ovine COX-1 complexed with several NSAIDs has been determined. Here we report the structures of unliganded murine COX-2 and complexes with flurbiprofen, indomethacin and SC-558, a selective COX-2 inhibitor, determined at 3.0 to 2.5 A resolution. These structures explain the structural basis for the selective inhibition of COX-2, and demonstrate some of the conformational changes associated with time-dependent inhibition.

A single amino acid difference between cyclooxygenase-1 (COX-1) and -2 (COX-2) reverses the selectivity of COX-2 specific inhibitors

Nonsteroidal anti-inflammatory drugs (NSAIDs) currently available for clinical use inhibit both COX-1 and COX-2. This suggests that clinically useful NSAIDs inhibit pro-inflammatory prostaglandins (PGs) derived from the activity of COX-2, as well as PGs in tissues like the stomach and kidney (via COX-1). A new class of compounds has recently been developed (SC-58125) that have a high degree of selectivity for the inducible form of cyxlooxygenase (COX-2) over the constitutive form (COX-1). This unique class of compounds exhibit a time-dependent irreversible inhibition of COX-2, while reversibly inhibiting COX-1. The molecular basis of this selectivity was probed by site-directed mutagenesis of the active site of COX-2. The sequence differences in the active site were determined by amino acid replacement of the COX-2 sequences based on the known crystal structure of COX-1, which revealed a single amino acid difference in the active site (valine 509 to isoleucine) and a series of differences at the mouth of the active site. Mutants with the single amino acid substitution in the active site and a combination of three changes in the mouth of the active site were made in human COX-2, expressed in insect cells and purified. The single amino acid change of valine 509 to isoleucine confers selectivity of COX-2 inhibitors in the class of SC-58125 and others of the same class (SC-236, NS-398), while commonly used NSAIDs such as indomethacin showed no change in selectivity. Substitutions of COX-1 sequences in COX-2 at the mouth of the active site of COX-2 did not change the selectivity of SC-58125. This indicates that the single amino acid substitution of isoleucine at position 509 for a valine is sufficient to confer COX-2 selectivity in this example of a diaryl-heterocycle COX inhibitor.

Metronidazole and clarithromycin resistance in Helicobacter pylori determined by measuring MICs of antimicrobial agents in color indicator egg yolk agar in a miniwell format. The Gastrointestinal Physiology Working Group of Universidad Peruana Cayetano Heredia and the Johns Hopkins University

Resistance of Helicobacter pylori to metronidazole often causes failure of commonly used combination drug treatment regimens. We determined the MICs of metronidazole and clarithromycin against 18 H. pylori strains from Peru using tetrazolium egg yolk (TEY) agar. The MIC results obtained by agar dilution with petri dishes were compared with the results found through a miniwell format. The results of the two protocols for measuring drug susceptibility differed by no more than 1 dilution in all cases. On TEY agar, bright-red H. pylori colonies were easy to identify against a yellow background. Sixty-one percent (11 of 18) of the strains were resistant to metronidazole (MIC, > or = 4 micrograms/ml) and 50% (9 of 18) were resistant to clarithromycin (MIC, > or = 0.125 micrograms/ml), whereas none (0 of 5) of the strains tested were resistant to tetracycline (MIC, > or = 1 micrograms/ml). Thus, the prevalence of metronidazole and clarithromycin resistance in Peru is higher than that in developed regions of the world. The miniwell plate with TEY agar allows easy H. pylori colony identification, requires about one-third less of the costly medium necessary for petri dish assaying, conserves space, and yields MICs equivalent to those with agar dilution in petri dishes.

Neutral location cues and cost/benefit analysis of visual attention shifts

The effects of location cuing on target responses can be examined by comparing informative and neutral cuing conditions. In particular, the magnitudes of costs of invalid location cuing and of benefits of valid location cuing can be determined by comparing invalid and valid cue responses to location-nonspecific neutral cue responses. Cost/benefit analysis is based on the assumption that neutral baseline measures reflect a general warning effect about the impending target's onset but no other specific target information. The experiments we report were carried out to determine the appropriateness of two baseline measures for cost/benefit analyses of direct (nonsymbolic) location cuing effects. We found that a multiple-cue baseline attenuated the benefits of valid cuing, and that a background-flash baseline arbitrarily attenuated costs or benefits depending on flash intensity. It is proposed that a background flash is the more suitable neutral cue because it is target-location-nonspecific, but that its intensity should be adjusted to elicit a target-onset warning signal of the same magnitude as the location cues with which it will be compared.

Posture in patients with shoulder overuse injuries and healthy individuals

Assessment of posture is an integral component of patient evaluation with shoulder overuse injuries. However, the professional literature contains relatively few studies that have assessed the relationship between posture, function, and injury. The purpose of this study was to determine the relationship and differences in postural variables within and between subjects with overuse injuries to the shoulder of healthy subjects. Thirty patient subjects and 30 healthy subjects matched for age and gender were recruited. Scapular protraction and rotation, forward head position, midthoracic curvature, and passive humeral elevation in the plane of the scapula were measured randomly in standing. All measurement techniques were standardized and validated. Intrarater and interrater reliability for all clinical measures were established before data collection. Forward head position was significantly greater (p < .001) in the patient group than the healthy group; humeral elevation was significantly greater (p < .001) in the healthy group than in the patient group and in the uninvolved shoulders (p < .01) than the involved shoulders within the patient group. Scapular protraction, rotation, midthoracic curvature, and scapular symmetry were not significantly different between groups. Scapula protraction and rotation were significantly related (p < .05) in the patient group. No other postural variables were related. Conclusions regarding the influence of posture to shoulder injury are inconclusive based on several confounding variables that may have affected the outcome.

Bioimpedance monitoring of rehydration in cholera

Measurement of bioimpedance (BI) is a simple non-invasive technique that relies on the different conductivity of tissues to define body composition and can be easily adapted to automated monitoring. We assessed the accuracy of BI in monitoring rehydration and acute fluid fluxes in 35 Peruvian cholera patients. Patients were monitored throughout the acute phase of diarrhoea and followed up at 3 and 10 days. BI was compared with other objective measures of dehydration including packed cell volume, serum protein, and calculated fluid balance. BI rapidly detected inadequate treatment and acute fluid flux, correlating highly with intravascular hydration as measured by serum protein and packed cell volume. BI values during dehydration were significantly raised compared with 10-day convalescent values and age-matched controls (p < 0.05). We also encountered an unexpected difference in the bioelectrical response to dehydration and rehydration between sexes. We conclude that BI has uses in monitoring dehydrated patients, in oral rehydration trials, and in physiological studies.

Metabolism of 1,3-di-(4-[N-(4,6-dimethyl-2-pyrimidinyl)sulphamoyl] phenyl)triazene (DDPSPT) in the rat

1. Six hours after rats were orally dosed with 1,3-di-(4-[N-(4,6-dimethyl-2-pyrimidinyl)sulphamoyl][U-14C]phenyl) triazene (14C-DDPSPT), approx. 81% of the 14C remained in the gastrointestinal tract (gut) and less than 3% was excreted in the urine. 2. Six hours after dosing, more than half of the 14C in the gut was present as DDPSPT. 14C-Labelled metabolites in the gut included 4-amino-N-(4,6-dimethyl-2-pyrimidinyl)-benzenesulphonamide (Sulmet), N4-glucosyl-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulphonamide (N4-gluc-Sulmet), 4-acetamido-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulphonamide (N4-acetyl-Sulmet), and [N-4,6-dimethyl-2-pyrimidinyl) benzenesulphonamide] (desamino-Sulmet). 3. 14C-Labelled compounds in the blood, liver and skeletal muscle included DDPSPT, Sulmet, N4-gluc-Sulmet, N4-acetyl-Sulmet and desamino-Sulmet. 4. There was little or no reaction of DDPSPT with cysteine, bovine serum albumin, AMP, GMP, or calf thymus deoxyribonucleic acid in vitro (pH 3, 5, 7 or 8).

Cellular senescence involves stochastic processes causing loss of expression of differentiated function genes: visualization by in situ hybridization for steroid 17 alpha-hydroxylase in bovine adrenocortical cells

When grown for long periods in culture, bovine adrenocortical cells lose the expression of a differentiated function gene, steroid 17 alpha-hydroxylase. Previously, we documented a decline in 17 alpha-hydroxylase mRNA with increasing culture passage level after induction with cyclic AMP (P. J. Hornsby et al., 1987, Proc. Natl. Acad. Sci. USA 84, 1580). We used in situ hybridization to investigate the loss of expression of this gene during cellular senescence at an individual cell level. In primary cultures, cells were uniformly positive for hybridization with cDNA for 17 alpha-hydroxylase after cyclic AMP induction. After two passages, cultures comprised a mixture of hybridizing and nonhybridizing cells. Cells appeared either to hybridize at a level comparable to that in primary cultures or to be nonhybridizing. When in situ hybridization was combined with immunofluorescence, cells positive for immunofluorescence were also positive for hybridization. Senescing mass cultures showed decreasing numbers of positive cells, and after 30 passages cultures comprised entirely nonhybridizing cells. Thus, the previously observed decline in overall 17 alpha-hydroxylase mRNA levels results from a decline in the fraction of expressing cells in the culture, and the rate of loss of expressing cells is in agreement with the rate of loss of total 17 alpha-hydroxylase mRNA. Primary clones, even when isolated at an early stage of clonal expansion, had mixtures of subclones of hybridizing and nonhybridizing cells. On recloning, hybridizing subclones usually produced uniformly nonhybridizing sub-subclones. Some subclones within primary clones had a morphology associated with replicative senescence (flattened cells with sparse intercellular contacts), yet had high numbers of hybridizing cells. We conclude that, in both mass and clonal populations, cells initially expressing 17 alpha-hydroxylase rapidly give rise to clones of nonexpressing cells. Such cells are continually derived by a stochastic process from cells originally expressing the gene.

Molecular modeling of calmodulin: a comparison with crystallographic data

Two methods of side-chain placement on a modeled protein have been examined. Two molecular models of calmodulin were constructed that differ in the treatment of side chains prior to optimization of the molecule. A virtual bond analysis program developed by Purisima and Scheraga was used to determine the backbone conformation based on 2.2 angstroms resolution C alpha coordinates for the molecules. In the first model, side chains were initially constructed in an extended conformation. In the second model, a conformational grid search technique was employed. Calcium ions were treated explicitly during energy optimization using CHARMM. The models are compared to a recently published refined crystal structure of calmodulin. The results indicate that the initial choices for side-chains, but also significant effects on the main-chain conformation and supersecondary structure. The conformational differences are discussed. Analysis of these and other methods makes possible the formulation of a methodology for more appropriate side-chain placement in modeled proteins.

A stereochemical model of the transpeptidation complex

Molecular models are proposed to describe the relative arrangement of aminoacyl and peptidyl tRNAs when bound to their respective A and P sites on the ribosome. The crystallographically determined structures of tRNAasp and tRNAphe have served as the models for these bound structures, while the imposed steric constraints for the model complexes were based on the results of published experimental data. The constructed models satisfy the stereochemical requirements needed for codon-anticodon interaction and for peptide bond formation. In this paper, the results of the complex containing tRNAphe as the A and P site bound transfer RNAs, is compared to a similarly constructed model which uses tRNAasp as the ribosome-bound transfer RNAs. The models have the following three major features: 1) the aminoacyl and peptidyl transfer RNAs assume an angle of approximately 45 degrees relative to each other; 2) in providing the proper stereochemistry for peptide bond condensation, a significant kink must be present in the messenger RNA between the A site and P site codons; and 3) a comparison of the two model complexes indicates that structural variations between the tRNAs or any allosteric transitions of the transfer RNAs associated with codon-anticodon recognition may be accommodated in the model by way of freedom of rotation about the phosphate backbone bonds in the mRNA between consecutive codons.

Biotransformation of gentian violet to leucogentian violet by human, rat, and chicken intestinal microflora

Cellular suspensions of microflora isolated from human feces and from intestinal contents of rat and chicken transformed the triphenylmethane dye gentian violet under anaerobic conditions. Pure cultures of nine genera of strict and facultative anaerobes were also active. All pure cultures and mixed intestinal microflora were found to convert the dye to leucogentian violet. Leucogentian violet was identified by HPLC retention time in a reverse phase system, and by mass spectral comparison with authentic compound. Leucogentian violet was extracted from the supernatants of the microfloral cultures, but the major portion of the metabolite was often bound to the cells (up to 87% of the metabolite produced by human microflora). Metabolites were quantitatively extracted from cell-free supernatants with 1-butanol/hexane, and from cellular pellets with trichloracetic acid. Leucogentian violet, amounting to 11% of the total radioactivity, was also detected by HPLC in ether extracts of feces collected from a female Fischer 344 rat dosed orally for 4 days with 14C-labeled gentian violet.

Synthesis and disposition of 14C-labelled gentian violet in F344 rats and B6C3F1 mice

The synthesis of [phenyl-U-14C]gentian violet from [U-14C]benzene is described. The 14C-labelled dye was administered by gavage to groups of male and female F344 rats which were killed at 2, 4, 14, 24 or 36 hr after the single dose. Radioactivity was measured in urine, and determined in faeces, liver, kidney, fatty tissue, gonads and muscle by combustion analysis. Residues were maximal at 4 hr in liver, kidney, muscle and gonads, and in fat they reached a plateau after 24 hr. Depletion half-lives for male and female livers were 14.5 and 17.0 hr, respectively. The 14C-labelled dye was also administered in multiple doses by gavage to both sexes of F344 rats and B6C3F1 hybrid mice for 7 days. The highest residue level was found in fatty tissue of females of both species, with a highly significant sex difference (P less than 0.01). Significant sex differences were also noted for residue levels in kidney and muscle tissue from both species and in mouse liver. Bile collected from cannulated rats contained 5.7-6.4% of a single oral dose of the dye. The results suggest that gentian violet is absorbed from the gastro-intestinal tract to a greater extent than has been reported for other triphenylmethane dyes.

3-Hydroxyxanthine: transplacental effects and ontogeny of related sulfate metabolism in rats and mice

The ontogeny of sulfate metabolism related to the metabolic activation of the carcinogenic purine N-oxide 3-hydroxyxanthine (3-OH-X) was studied in noninbred Sprague-Dawley rats. Sulfotransferase activity toward 3-OH-X was detectable in most fetal livers near term at about 25% of adult values and increased slowly after birth. This activity was also present in placentas. Compared to 3-OH-X sulfotransferase, sulfotransferase activity toward p-nitrophenol was lower in fetal livers and was not detected in placentas. Sulfohydrolase activity toward 3'-phosphoadenosine-5'-phosphosulfate was higher in fetal and newborn livers and in placentas than in adult liver. In a parallel transplacential carcinogenicity assay, a low but significant percentage of male rats exposed as fetuses to multiple high doses of 3-OH-X developed single liver carcinomas. After the lowest transplacental dose, the incidence of degenerative kidney disease in old male offspring was significantly higher than that in controls. In an assay with mice, (C57BL/6 X BALB/c)F1 mice exposed transplacentally to 3-OH-X experienced significantly greater perinatal morality and fewer lung adenomas among the surviviors at 20 months of age than did the controls.

Conversion of the oncogenic 1-methylguanine 3-oxide to 3-hydroxy-1-methylxanthine

Deamination of the oncogenic 1-methylguanine 3-oxide occurs to a significant extent in rats to yield 3-hydroxy-1-methylxanthine and its metabolites. When 3-hydroxy-1-methylxanthine is administered, 1-methyl-8-methylthioxanthine can be recovered from urine and released from hepatic protein. No 1-methyl-8-methylthioguanine was detected in urine or bound to protein. There is no evidence of significant activation of 1-methylguanine 3-oxide by sulfotransferase, but deamination to the oncogenic 3-hydroxy-1-methylxanthine suffices to explain its oncogenicity.

Reaction of diethyl pyrocarbonate with nucleic acid components. I. Adenine

The use of diethyl pyrocarbonate as a nuclease inhibitor in the preparation of RNA of high molecular weight has prompted a study of the possible reactions of this compound with nucleic acid components under the conditions generally employed for providing inhibition. The first substrate investigated was adenine, which has been found to undergo ring opening with the formation of 5(4)-N-carbethoxyaminoimidazole-4(5)-N'- carbethoxycarboxamidine (II). This product was converted efficiently to isoguanine by treatment with ammonia. The structure of II was established by spectroscopy. For comparisons of reactivity and of spectroscopic and chromatographic properties with the adenine-diethyl pyrocarbonate product, the compounds 9-carbethoxyadenine, 6-N-carbethoxyaminopurine (V), and 6-ethylaminopurine were made; compound V was made by employing the 1-ethoxyethyl protecting group in the synthetic sequence. Purine compounds can be converted to 9-(1-ethoxyethyl) derivatives simply by refluxing in acetal. The facile reaction of adenine with diethyl pyrocarbonate illustrates the importance of gaining information as to the fate of various nucleic acid components in the presence of diethyl pyrocarbonate.

The Importance of Whole Blood Transfusions in the Management of Severe Burns

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The Origin of the M. Pectoralis Minor

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