Relationship between variations in estradiol and progesterone levels across the menstrual cycle and human performance

RATIONALE

Studies about whether or not the cognitive performance of women is influenced by changes in levels of sex steroid hormones across the menstrual cycle have produced ambiguous results.

OBJECTIVES

This study tested whether flight simulator performance differs significantly between the menstrual and the luteal phase of the menstrual cycle.

METHODS

In a within-subjects design, 24 female pilots were tested twice during their menstrual cycle: once during the menstrual and once during the luteal phase. On both test days they performed a 75-min simulator flight in a Frasca 141, a popular pilot training device.

RESULTS

Despite highly significant differences in estradiol (E2) as well as progesterone (P) levels on the 2 test days, and despite excluding subjects with anovulatory cycles from the analyses, there were no significant differences in overall flight performance between the menstrual and luteal phases. We found no significant correlations between E2 or P levels and flight performance.

CONCLUSIONS

We found no evidence that the tested menstrual cycle phases and their associated E2 and P levels significantly influence flight simulator performance. We consider these negative findings based on 24 subjects meaningful because previous studies on the influence of menstrual cycle on cognitive performance have not involved complex "real world" tasks such as piloting an aircraft and they obtained inconsistent results.

Teaching and learning about sexual histories during undergraduate medical education: a comparison of two approaches

Experiential small group workshops on taking a sexual history were introduced at Imperial College School of Medicine (ICSM). With the introduction of a new curriculum and an increase in the number of students, together with a growing awareness of economic constraints in medical education, a large group session on the same topic was developed. In both sessions students identify barriers to taking a sexual history, contexts in which a sexual history is appropriate and skills necessary for an effective sexual history interview. This paper describes and contrasts the content, methodology and student evaluations of both types of sessions. The results showed that in the short term students perceived benefits from both methods of teaching. Further work is required to determine the long-term effects of such training.

A longitudinal study of apolipoprotein-E genotype and depressive symptoms in community-dwelling older adults

The Apolipoprotein-E (APOE) epsilon 4 allele is a risk factor for Alzheimer's disease (AD) and cognitive decline in older adults. Depression may also be a risk factor for dementia, and depression is important in the differential diagnosis of dementia. The authors performed a 5-year longitudinal study of APOE genotype and change in Geriatric Depression Scale scores in 113 community-dwelling older adults. No association was observed between APOE genotype and change in depressive symptoms. These results do not support the hypothesis that the APOE epsilon 4 allele is associated with depression. Important objections have been raised to APOE genotyping in the diagnosis of AD. However, the specificity of APOE genotyping in AD diagnosis would not appear to be compromised by an association with depression.

Relationship of CogScreen-AE to flight simulator performance and pilot age

OBJECTIVES

We report on the relationship between CogScreen-Aeromedical Edition (AE) factor scores and flight simulator performance in aircraft pilots aged 50-69.

METHODS

Some 100 licensed, civilian aviators (average age 58+/-5.3 yr) performed aviation tasks in a Frasca model 141 flight simulator and the CogScreen-AE battery. The aviation performance indices were: a) staying on course; b) dialing in communication frequencies; c) avoiding conflicting traffic; d) monitoring cockpit instruments; e) executing the approach; and f) a summary score, which was the mean of these scores. The CogScreen predictors were based on a factor structure reported by Kay (11), which comprised 28 CogScreen scores. Through principal components analysis of Kay's nine factors, we reduced the number of predictors to five composite CogScreen scores: Speed/Working Memory (WM), Visual Associative Memory, Motor Coordination, Tracking, and Attribute Identification.

RESULTS

Speed/WM scores had the highest correlation with the flight summary score, Spearman r(rho) = 0.57. A stepwise-forward multiple regression analysis indicated that four CogScreen variables could explain 45% of the variance in flight summary scores. Significant predictors, in order of entry, were: Speed/WM, Visual Associative Memory, Motor Coordination, and Tracking (p<0.05). Pilot age was found to significantly improve prediction beyond that which could be predicted by the four cognitive variables. In addition, there was some evidence for specific ability relationships between certain flight component scores and CogScreen scores, such as approach performance and tracking errors.

CONCLUSIONS

These data support the validity of CogScreen-AE as a cognitive battery that taps skills relevant to piloting.

Pharmacology and biological efficacy of a recombinant, humanized, single-chain antibody C5 complement inhibitor in patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response that causes substantial clinical morbidity. Activation of complement during CPB contributes significantly to this inflammatory process. We examined the capability of a novel therapeutic complement inhibitor to prevent pathological complement activation and tissue injury in patients undergoing CPB.

METHODS AND RESULTS

A humanized, recombinant, single-chain antibody specific for human C5, h5G1.1-scFv, was intravenously administered in 1 of 4 doses ranging from 0.2 to 2.0 mg/kg before CPB. h5G1.1-scFv was found to be safe and well tolerated. Pharmacokinetic analysis revealed a sustained half-life from 7.0 to 14.5 hours. Pharmacodynamic analysis demonstrated significant dose-dependent inhibition of complement hemolytic activity for up to 14 hours at 2 mg/kg. The generation of proinflammatory complement byproducts (sC5b-9) was effectively inhibited in a dose-dependent fashion. Leukocyte activation, as measured by surface expression of CD11b, was reduced (P<0.05) in patients who received 1 and 2 mg/kg. There was a 40% reduction in myocardial injury (creatine kinase-MB release, P=0.05) in patients who received 2 mg/kg. Sequential Mini-Mental State Examinations (MMSE) demonstrated an 80% reduction in new cognitive deficits (P<0.05) in patients treated with 2 mg/kg. Finally, there was a 1-U reduction in postoperative blood loss (P<0. 05) in patients who received 1 or 2 mg/kg.

CONCLUSIONS

A single-chain antibody specific for human C5 is a safe and effective inhibitor of pathological complement activation in patients undergoing CPB. In addition to significantly reducing sC5b-9 formation and leukocyte CD11b expression, C5 inhibition significantly attenuates postoperative myocardial injury, cognitive deficits, and blood loss. These data suggest that C5 inhibition may represent a novel therapeutic strategy for preventing complement-mediated inflammation and tissue injury.

The validation of the short form of the Geriatric Depression Scale (GDS) in Greece

The Geriatric Depression Scale-15 (GDS-15) is a short, 15-item instrument specifically designed to assess depression in geriatric populations. Its items require a yes/no response. The Geriatric Depression Scale was first introduced by Yesavage et al. in 1983, and the short form (GDS-15) was developed by Sheikh and Yesavage in 1986. The aim of the current study was the standardization of the GDS-15 for use in Greece. Subjects were divided into Group A: 168 control subjects, and Group B: 103 patients suffering from clinically diagnosed depression. All were over 65 years of age. A score of 6/7 on the GDS-15 was found to be the best cut-off point for diagnosing depression in an elderly Greek population, with Sensitivity = 92.23 and Specificity = 95.24. GDS-15 manifests high internal consistency with Cronbach's alpha = 0.94, and all items seem to be equivalent. Factor Analysis of the GDS-15 revealed 4 factors: a cognitive (thought content), an affective, a functional, and a factor that reflects helplessness and fear for the future. The two diagnostic groups differed on all 4 factors scores at p-value <0.001.

Relationship of age and simulated flight performance

OBJECTIVE

To determine the relationship between age and aviator performance on a flight simulator.

DESIGN

A cross-sectional observational study.

PARTICIPANTS

The sample consisted of 100 aviators aged 50 to 69 (mean = 58).

MAIN OUTCOME MEASURES

Pilots were tested on a Frasca 141 flight simulator (Urbana, IL), linked to a UNIX-based IRIS 4D computer (Silicon Graphics, Mountain View, CA), which both generated graphics of the environment in which the pilots flew and collected data concerning the aircraft's flight conditions.

RESULTS

We found that increased age was significantly associated with decreased aviator performance on a flight simulator.

CONCLUSIONS

Although there was a significant relationship between increased age and decreased aviator performance, age explained 22% or less of the variance of performance on different flight tasks; hence, other factors are also important in explaining the performance of older pilots.

Relationship between brain electrical activity and cortical perfusion in normal subjects

Cerebral glucose uptake and perfusion are accepted as tightly coupled measures of energy utilization in both normal and diseased brain. The coupling of brain electrical activity to perfusion has been demonstrated, however, only in the presence of chronic brain disease. Very few studies have examined the relationship between cerebral electrical activity and energy utilization in normal brain tissue. To clarify this relationship, we performed 33 H2(15)O-positron emission tomography (PET) scans in six normal subjects both at rest and during a simple motor task, and acquired surface-recorded quantitative electroencephalogram (QEEG) data simultaneously with isotope injection. We examined the associations between cerebral perfusion directly underlying each recording electrode and three QEEG measures (absolute power, relative power, and cordance). All EEG measures had moderately strong coupling with perfusion at most frequency bands, although the directions of the associations differed from those previously reported in subjects with stroke or dementia. Of the three QEEG measures examined, cordance had the strongest relationship with perfusion (multiple R2 = 0.58). Cordance and PET were equally effective in detecting lateralized activation associated with the motor task, while EEG power did not detect this activation. Electrodes in the concordant state had a significantly higher mean perfusion than those in the discordant state. These results indicate that normal brain electrical activity has a moderately strong association with cerebral perfusion. Cordance may be the most useful QEEG measure for monitoring cerebral perfusion in subjects without chronic brain disease.

Effects of menstrual cycle and female sex steroids on ethanol pharmacokinetics

This study investigated the influence of menstrual cycle and female sex steroid levels on ethanol pharmacokinetics. In a within-subjects design, 24 female volunteers each consumed 0.67 g x kg(-1) ethanol during the menstrual and luteal phases of their menstrual cycle. On each test day, we collected blood samples before ethanol administration to determine estradiol (E2) and progesterone (P) levels and to confirm ovulation. We took 20 or more postdrink breath ethanol concentration readings and examined pharmacokinetic differences between the two phases, using classical pharmacokinetic measures, as well as Michaelis-Menten measures. Despite highly significant differences in measured E2 as well as P levels on the 2 test days, and despite excluding subjects with anovulatory cycles from the analysis, there were no significant differences between menstrual and luteal phases for any of the pharmacokinetic variables. We found no correlation between E2 or P levels and any of the pharmacokinetic measures. In summary, we found no evidence that the tested menstrual cycle phases or varying E2 and progesterone levels significantly influence ethanol pharmacokinetics. Because previous studies about the topic have used few subjects and revealed controversial results, we consider our negative findings based on 24 subjects meaningful.

Gender differences in moderate drinking effects

Women appear to become more impaired than men after drinking equivalent amounts of alcohol, achieving higher blood alcohol concentrations even when doses are adjusted for body weight. This finding may be attributable in part to gender differences in total body water content. Men and women appear to eliminate approximately the same total amount of alcohol per unit body weight per hour. However, women seem to eliminate significantly more alcohol per unit of lean body mass per hour than men. Some studies report that women are more susceptible than men to alcohol-related impairment of cognitive performance, especially in tasks involving delayed memory or divided attention functions. Psychomotor performance impairment, however, does not appear to be affected by gender. This article provides an overview of alcohol metabolism (pharmacokinetics) and reviews recent studies on gender differences in alcohol absorption, distribution, elimination, and impairment. Speculation that gender differences in alcohol pharmacokinetics or alcohol-induced performance impairment may be caused by the menstrual cycle and variations in female sex hormones are discussed. It is concluded that the menstrual cycle is unlikely to influence alcohol pharmacokinetics.

The APOE epsilon4 allele is associated with decline on delayed recall performance in community-dwelling older adults

OBJECTIVE

This study investigated whether the Apolipoprotein (APOE) epsilon4 allele was associated with cognitive decline in community-dwelling older adults.

DESIGN

Longitudinal cognitive performance of older adults with the epsilon3/epsilon4 genotype was compared with that of older adults with the epsilon3/epsilon3 genotype.

SETTING

Aging Clinical Research Center, Stanford University.

PARTICIPANTS

One hundred community-dwelling older adults were recruited from a pool of 531 individuals who had participated in a memory training study 4 to 5 years earlier. These individuals were concerned about their memory functioning and were recruited through newspaper advertisements and contacts with local senior centers. The 100 individuals who agreed to participate in the follow-up investigation were between 59 and 95 years of age.

MEASUREMENTS

At both baseline and follow-up, subjects were administered a battery of seven cognitive tests that examined verbal and spatial memory, attention, speed-of-processing, and language abilities. APOE genotype was determined at follow-up.

RESULTS

Individuals with the epsilon3/epsilon4 APOE genotype were significantly younger than individuals with the APOE epsilon3/epsilon3 genotype. No significant differences were observed between the two groups on measures of attention, speed-of-processing, vocabulary, immediate verbal memory, and immediate spatial memory. However, those older adults with the epsilon3/epsilon4 genotype exhibited significantly greater decline in performance on delayed recall of verbal material than did those with the epsilon3/epsilon3 APOE genotype.

CONCLUSION

These findings are consistent with previous studies, which suggest that the APOE epsilon4 allele predicts decline on measures of delayed recall.

Assessing the accuracy of topographic EEG mapping for determining local brain function

OBJECTIVE

There has been considerable discussion regarding the accuracy of topographic electroencephalographic (EEG) maps for assessing local cerebral function. We performed this study to test the accuracy of EEG mapping by examining the association between electrical activity and the perfusion under each electrode as another measure of local cerebral function.

METHODS

EEG mapping was performed simultaneously with (H15)2O positron emission tomography (PET) scanning in 6 normal adult subjects, both at rest and during a simple motor task. EEG data were processed using 3 different montages; two EEG power measures (absolute and relative power) were examined.

RESULTS

Relative power had much stronger associations with perfusion than did absolute power. In addition, calculating power for bipolar electrode pairs and averaging power over electrode pairs sharing a common electrode yielded stronger associations with perfusion than data from referential or single source montages.

CONCLUSIONS

These findings indicate (1) that topographic EEG mapping can accurately reflect local brain function in a way that is comparable to other methods, and (2) that the choice of EEG measure and montage have a significant influence on the degree with which maps reflect this local activity and function.

Influence of nicotine on simulator flight performance in non-smokers

In a placebo-controlled study, we investigated the influence of nicotine on late-day aviation performance in 15 non-smoking subjects. In a within-subjects design, subjects were tested on 2 days, each lasting 8 h and consisting of three 75-min simulator flights (late-afternoon practice, evening test, night test). Prior to each test, subjects received either nicotine polacrilex 2 mg or placebo gum. As expected, overall performance was significantly better after nicotine, compared to placebo (P < 0.01). Post-hoc analysis of individual flight tasks showed that nicotine improved scores on approach to landing, a task which appears to require sustained attention. We conclude that nicotine may improve late-day flight performance in non-smoking aviators.

Brain structure and function and the outcomes of treatment for depression

BACKGROUND

Depressed patients have a variety of brain structural alterations, the most common being atrophy and deep white-matter lesions. Alterations in brain function also are common, particularly regional decreases in cerebral metabolism and perfusion.

METHOD

We review here the evidence that alterations in brain structure and function may explain some of the heterogeneity in outcomes of depression. We also report initial results suggesting that measurement of brain structure and function may help to predict outcomes of treatment for depression. Brain structure was examined using three-dimensional reconstruction and volumetric analysis of magnetic resonance imaging (MRI) scans. Brain function was examined using quantitative electroencephalography (QEEG), performed at baseline and serially during the course of treatment. QEEG measures included coherence (a measure of synchronized activity between brain regions) and cordance (a measure strongly associated with regional cerebral perfusion).

RESULTS

Depressed patients have been reported to have larger volumes of white-matter lesions than controls. We have found that some types of white-matter lesions are associated with lower coherence and that subjects with low coherence had significantly poorer outcomes of treatment for depression at 2-year follow-up. Depressed subjects had low cordance at baseline, which decreased further during the course of effective treatment. Subjects who did not improve had little or no change in cordance. Changes in cordance were detected prior to the onset of clinical response, with decreases seen as early as 48 hours after the initiation of treatment in subjects who showed eventual response.

CONCLUSION

These preliminary results suggest that functional imaging using QEEG may be useful for assessing, and possibly predicting, outcomes of treatment for depression.

African horsesickness virus VP7 sub-unit vaccine protects mice against a lethal, heterologous serotype challenge

An established mouse model was used to evaluate the effectiveness of the major outer core protein of African horsesickness virus (AHSV), VP7, as a subunit vaccine. Adult female BALB/c mice were immunized with VP7 crystals purified from BHK cells infected with AHSV serotype 9 (AHSV-9), using three inoculations in Freund's adjuvant. Eighty to one hundred per cent of the immunized mice were protected against a heterologous challenge with a known lethal dose of AHSV-7. The protected immunized mice did not develop any clinical signs characteristic of virulent AHSV infection in this model during the study. In contrast, 80-100% mortality was observed in the non-immunized mice that received the same challenge virus. Subsequent studies indicated that a single inoculation of 1.5 micrograms purified AHSV VP7 in Freund's complete adjuvant was sufficient to protect at least 90% of mice from AHSV-7 challenge. If the antigen was presented in the absence of Freund's complete adjuvant, 70% of the mice were still protected by one inoculation of VP7 crystals. Titres of circulating antibody against AHSV VP7, determined by competitive ELISA, did not appear to correlate with protection and passive antibody transfer from immunized BALB/c mice failed to protect syngeneic recipients from AHSV-7 challenge. Therefore, the observed protection is unlikely to be due to an antibody-mediated immune response. The number of viraemic mice and the duration of viraemia post-challenge was significantly reduced in vaccinated mice compared to non-vaccinated controls. However, the levels of viraemia were similar.

Cognitive changes in young-old adults: effect of family history of dementia

Cognitive performance of 40 first-degree relatives of patients with probable Alzheimer disease was compared to that of 24 matched controls without a family history of dementia. Across a test-retest interval ranging from 1 to 6 years, relatives more often showed evidence of cognitive decline, and in multivariate analyses of memory and intelligence measures, relatives of patients with early-onset dementia (< 67 years) showed greater decline than controls or relatives of patients with late-onset dementia. All changes observed to date are in the subclinical range, and further follow-up will be needed to determine the reliability of change trajectories. However, the findings suggest that family history of dementia may be worthy of monitoring in research on normal cognitive aging.

Changing practice in pain management

This article describes the formation of a multi-disciplinary group to improve the management of post-operative pain for orthopaedic patients. The three factors which precipitated the activities of the group are discussed, namely the presence of concerned professionals, local research, and a small number of complaints from patients. The article then describes the work of the pain management group, and how their decisions were both put into practice and monitored.

The use of African horse sickness virus VP7 antigen, synthesised in bacteria, and anti-VP7 monoclonal antibodies in a competitive ELISA

A full-length cDNA clone of genome segment 7 of African Horse Sickness Virus, serotype 9 (AHSV9) was obtained using the PCR technique. The clone was sequenced and found to be 98.27% homologous to the previously published sequence of the equivalent cDNA clone from AHSV4 at the nucleotide level and to exhibit 99.7% identity at the amino acid level. The cDNA clone was transferred to pGEX-2T (Pharmacia), a bacterial expression vector, such that the reading frame of AHSV9 VP7 was continuous with that of the bacterial glutathione-S-transferase (GST) protein, under the control of the bacterial tac promoter. On induction with IPTG a fusion protein consisting of GST and VP7 was synthesised, which was readily purified on a GST-sepharose column (Pharmacia). The fusion protein reacted equally well in an indirect ELISA using monoclonal antibodies specific for AHSV9 VP7 or polyclonal guinea pig antisera raised against AHSV9 infectious sub-viral particles. This protein was also shown to be a suitable substitute for virus antigen, prepared from infected BHK cell extracts, in a competitive ELISA. Antibodies titres recorded for AHSV9 positive and negative horse sera were similar in the competitive ELISA using either bacterial AHSV VP7 or BHK extracted virus as the source of antigen, in combination with monoclonal or polyclonal antibodies, respectively, as the detectors.

Monozygotic twins with Parkinson's disease

A pair of monozygotic twins concordant for Parkinson's disease are described. The issue of genetic factors in Parkinson's disease is discussed.