Revisiting reliability of quantified perineal ultrasound: Bland and Altman analysis of a new protocol for the rectangular coordinate method.

AIMS: This study tested the reliability of a new protocol for the rectangular coordinate method of quantifying perineal ultrasound. METHODS: Representative scans of healthy primiparous females were quantified by positioning a pubic bone template, drawn onto an acetate sheet containing x-y axes, over scans, by aligning the x-axis with the pubic bone central axis. Values for x (D(x)) and y (D(y)) located the urethrovesical junction (UVJ) at Rest, and at maximal Valsalva and Kegel. Range of motion (V-K) was calculated. Bland and Altman analysis, correlations, and t-tests determined intra- and inter-rater reliability, and variance due to designation of the pubic bone central axis (template control). RESULTS: Correlations averaged 0.72, 0.70, and 0.92 for intra-rater, inter-rater, and template control experiments. D(x) Rest, D(x) Kegel, and V-K were reliable in all experiments. First and second measures for inter-rater D(y) Rest and D(y) Kegel, and template control D(y) Valsalva were significantly different. Bland and Altman analysis showed D(y) Rest, D(y) Kegel, and D(x) and D(y) Valsalva for both reliability experiments to have limits of agreement (LOA's) large enough to explain >or=50% of the actual value ranges. Template control LOA's explained

Gender differences in the cortical electrophysiological processing of visual emotional stimuli.

The processing of visual emotional stimuli has been investigated previously; however, gender differences in the processing of emotional stimuli remain to be clarified. The aim of the current study was to use steady-state probe topography (SSPT) to examine steady-state visually evoked potentials (SSVEPs) during the processing of pleasant and unpleasant images relative to neutral images, and to determine whether this processing differs between males and females. Thirty participants (15 males and 15 females) viewed 75 images low on the arousal dimension (categorised as pleasant, neutral or unpleasant) selected from the International Affective Picture System (IAPS), whilst a 13-Hz sinusoidal white visual flicker was superimposed over the visual field and brain electrical activity was recorded from 64 electrode sites. Results suggest that pleasant and unpleasant images relative to neutral images are associated with reductions in frontal latency and occipital amplitude. In addition, electrophysiological gender differences were observed despite there being no differences found between males and females on subjective mood or behavioural ratings of presented images (valence and arousal dimensions). The main gender difference reported in the current study related to the processing of unpleasant images (relative to neutral images) which is associated with widespread frontal latency reductions (predominantly right sided) in females but not in males. Our results suggest that gender differences do exist in the processing of visual emotional stimuli, and illustrate the importance of taking these differences into account during investigations of emotional processing. Finally, these gender differences may have implications for the pathophysiology of mood disorders such as depression.

The effect of repeated pulses of light at the same time on period responses of the rat circadian pacemaker.

A consequence of simple velocity-based models is that, in response to light pulses, the circadian period should adjust inversely to phase. In addition, because of the interaction of circadian period and phase response, earlier circadian period changes should modify later circadian period changes. The literature contains few mentions of response curves of circadian period responses following light pulses. Rats were exposed to four pulses of light (60 minutes, 1000 lux) at the same circadian time, a minimum of 26 days apart; we assessed period responses and possible bias in the period-response curve. Modulation of circadian period following light-induced phase responses was examined by assessing the period of running wheel activity onset. Phase and circadian period were not consistently found to share an inverse relationship. Moreover, biases in initial period tended to be increased by the experimental protocol regardless of circadian time of pulse. Rats with a short initial (high-velocity) period had a lengthened period, while rats with a long initial period (low velocity) tended to have a reduce period. However, rats with a long initial period were phase delay biased, not phase advance biased. These results do not support a simple velocity model of the pacemaker.

Acute increases in night-time plasma melatonin levels following a period of meditation.

To determine whether a period of meditation could influence melatonin levels, two groups of meditators were tested in a repeated measures design for changes in plasma melatonin levels at midnight. Experienced meditators practising either TM-Sidhi or another internationally well known form of yoga showed significantly higher plasma melatonin levels in the period immediately following meditation compared with the same period at the same time on a control night. It is concluded that meditation, at least in the two forms studied here, can affect plasma melatonin levels. It remains to be determined whether this is achieved through decreased hepatic metabolism of the hormone or via a direct effect on pineal physiology. Either way, facilitation of higher physiological melatonin levels at appropriate times of day might be one avenue through which the claimed health promoting effects of meditation occur.

Melatonin profiles and sleep characteristics in boys with fragile X syndrome: a preliminary study.

Sleep patterns and endogenous melatonin profiles in 13 fragile X boys between the age of 4.7 and 11.0 years were compared to those of 8 age-matched, normal control boys. Parents recorded sleep patterns on a Sleep Diary Chart for 14 consecutive days. Twelve saliva samples were obtained from 8 fragile X participants and all of the controls over 48 hours for the assessment of salivary melatonin profiles. The results showed greater variability in total sleep time and difficulty in sleep maintenance in fragile X boys compared with the control participants. Nocturnal melatonin production, expressed as both peak level and area under the concentration-time curve between 20:00 h and 08:00 h, were found to be significantly larger in fragile X boys than in controls. Additionally, the mean of the minimum daytime melatonin levels recorded was significantly higher for the fragile X group. Elevated levels in some fragile X boys relative to the range seen in controls, occurring either during the day or at night, or in both segments of the secretory profile for some individuals, may be due in part to overactivity of the sympathetic nervous system. Alternative molecular mechanisms leading to changes in melatonin profiles in fragile X are also discussed.

The effect of multiple pulses of light on the circadian phase response of the rat.

Multiple pulses of light administered to humans have been reported to result in type 0 phase responses. These results suggest the underlying pacemaker to be nonsimple. At present, results with this type of protocol have only been reported for humans. Therefore, multiple pulses of light were administered to rats. Rats were exposed to one, two, three, or four pulses of light for 5 h (1000 lux) at successive 24-h intervals. Results did not suggest a type 0 phase response. Nonetheless, results with a second, third, or fourth light exposure were not fully predictable from a phase response curve derived from a single light pulse.

A therapeutic role for melatonin antagonism in experimental models of Parkinson's disease.

To determine the effects of endogenous and exogenous melatonin on experimental models of Parkinson's disease (PD), Sprague-Dawley rats were exposed to intracerebroventricular implants of slow release melatonin, pinealectomy (PX), or constant light (LL) and then injected with central 6-hydroxydopamine (6-OHDA) or i.p. 1-methyl-4-phenyl,1-1,2,3,6-tetrahydropyridine (MPTP). The resulting impairment of motor function and related behavioural impairment were exacerbated by melatonin implantation, while PX and exposure to LL significantly reduced the severity of experimental PD. These results are consistent with previous work highlighting the importance of aberrant amine production in neurological disease and demonstrate that treatments that reduce endogenous melatonin bioavailability can ameliorate experimental PD. Furthermore, these findings illustrate that melatonin is not the universal remedy that it is currently claimed to be, and may pose considerable problems in neurological diseases characterised by dopamine degeneration.

Changes in human plasma melatonin profiles in response to 50 Hz magnetic field exposure.

The effects of power-frequency magnetic fields on nighttime plasma melatonin were studied in a group of 30 adult male human subjects. Exposure consisted of 20 microT (200 mG) at 50 Hz (circularly polarized) at certain times in relation to the predicted time of onset of rise in melatonin concentration for a particular individual (the time of onset was predicted from a previous screening night). Response to this exposure was compared to sham-exposure (in random order). When exposure preceded onset of rise, a significant delay in onset time relative to sham-exposure of approximately half an hour was observed, with indications (marginally significant) of a reduction in maximum melatonin level. Analysis of distribution of time-delays is consistent with two populations: those individuals who respond (around 20%) and those that do not. Magnetic fields generated by square-wave currents produce more marked reductions in the maximum level when compared to sinusoidal waveforms, but there was no significant difference in onset time.

Orphan neurones and amine excess: the functional neuropathology of Parkinsonism and neuropsychiatric disease.

The aetiology and treatment of Parkinsonism is currently conceptualised within a dopamine (DA) deficiency-repletion framework. Loss of striatal DA is thought to cause motor impairment of which tremor, bradykinaesia and rigidity are prominent features. Repletion of deficient DA should at least minimise parkinsonian signs and symptoms. In Section 2, based on extensive pre-clinical and clinical findings, the instability of this approach to Parkinsonism is scrutinised as the existing negative findings challenging the DA deficiency hypothesis are reviewed and reinterpreted. In Section 3 it is suggested that Parkinsonism is due to a DA excess far from the striatum in the area of the posterior lateral hypothalamus (PLH) and the substantia nigra (SN). This unique area, around the diencephalon/mesencephalon border (DCMCB), is packed with many ascending and descending fibres which undergo functional transformation during degeneration, collectively labelled 'orphan neurones'. These malformed cells remain functional resulting in pathological release of transmitter and perpetual neurotoxicity. Orphan neurone formation is commonly observed in the PLH of animals and in man exhibiting Parkinsonism. The mechanism by which orphan neurones impair motor function is analogous to that seen in the diseased human heart. From this perspective, to conceptualise orphan neurones at the DCMCB as 'Time bombs in the brain' is neither fanciful nor unrealistic [E.M. Stricker, M.J. Zigmond, Comments on effects of nigro-striatal dopamine lesions, Appetite 5 (1984) 266-267] as the DA excess phenomenon demands a different therapeutic approach for the management of Parkinsonism. In Section 4 the focus is on this novel concept of treatment strategies by concentrating on non-invasive, pharmacological and surgical modification of functional orphan neurones as they affect adjacent systems. The Orphan neurone/DA excess hypothesis permits a more comprehensive and defendable interpretation of the interrelationship between Parkinsonism and schizophrenia and other related disorders.

Antibiotic resistance in Streptomyces lividans: fluorescence assay for streptogramin B lyase.

A fluorescence assay for streptogramin B lyase, an enzyme that confers resistance to streptogramin B antibiotics, has been developed. The antibiotic substrates are fluorescent and the linear peptide products formed in the lyase-catalyzed reaction are relatively nonfluorescent. The assay has potential for assessing bacterial resistance to streptogramin B antibiotics and will be utilized to direct the purification of streptogramin B lyase from bacterial extracts.

The application of positron emission tomography to the study of the normal menstrual cycle.

Positron emission tomography (PET) was used to investigate regions of the brain that are selectively affected during different phases of the normal menstrual cycle. A total of 10 healthy 18-29 year old female volunteers had PET measurements of brain glucose metabolism between days 5 and 9 of the follicular phase when plasma concentrations of oestradiol and progesterone were relatively low and between days 5 and 8 of the luteal phase when plasma concentrations of oestradiol and progesterone were relatively high. Automated algorithms were used to align the PET images in each individual, transform them into the coordinates of a brain atlas, control for variations in whole brain measurements and compute t-score maps of phase-related differences in regional glucose metabolism. The mid-follicular phase was associated with significantly higher glucose metabolism in thalamic, prefrontal, temporoparietal and inferior temporal regions. The mid-luteal phase was associated with significantly higher glucose metabolism in superior temporal, anterior temporal, occipital, cerebellar, cingulate and anterior insular regions. While this study should be considered to be exploratory, it provides normative data for future studies and illustrates how PET can be used to help characterize relationships between phases of the female life cycle, temporally related disorders and local functions of the living human brain.

Daily restricted feeding effects on the circadian activity rhythms of the stripe-faced dunnart, Sminthopsis macroura.

The effect of daily restricted feeding (RF) on the circadian wheel-running activity rhythms of the stripe-faced dunnart (Sminthopsis macroura) was examined. Dunnarts were presented with a 2-h meal in the middle of the light period of a 14:10 light:dark (LD) cycle and during constant dim light (LL). No meal-anticipatory activity (AA) was observed in any of the dunnarts during the experiment. This contrasts with previous work where AA has been reported in dunnarts subjected to RF. In LL, RF acted as a weak zeitgeber for the circadian activity rhythms of the dunnart. Evidence supporting this observation was the fact that 4/8 dunnarts' activity rhythms were entrained by RF, 2 showed relative coordination, and 1 exhibited bouncing phenomenon. In other species of marsupials and in rats, it has been proposed that RF entrains a food-entrainable pacemaker, which, in turn, entrains, via coupling, the suprachiasmatic-based, light-entrainable pacemaker. The findings of the present study differ from those reported previously in that no observable AA was entrained but the light-entrainable pacemaker was entrained by RF. In the dunnart, it remains to be determined whether RF directly entrains the light-entrainable pacemaker or whether RF entrains a food-entrainable pacemaker and in turn, via coupling, the light-entrainable pacemaker.

Inhibition of melatonin secretion onset by low levels of illumination.

Melatonin is a hormone released during darkness under the control of the hypothalamic circadian pacemaker. It has been shown that melatonin is suppressed by light as a function of intensity, with low levels of illumination producing small effects and more intense light greater, but not complete inhibition. The studies which lead to these conclusions administered light subsequent to the secretion pattern being well established. Light as low as 250 lux administered during the normal onset of secretion can reduce melatonin to below detectable levels. The onset of melatonin secretion was delayed for at least an hour during 250 lux exposure and did not rise until termination of light exposure (two hours after control melatonin onset) with higher illumination (500, 1000 and 2500 lux). This tentatively indicates that duration of the inhibition is intensity dependent. It is suggested that the experimental paradigm used in the present study may be a more realistic representation of the effect of normal light exposure (both natural and artificial) on the circadian system, and that findings may be pertinent to the aetiology of certain sleep onset insomnias, which would include delayed sleep phase syndrome (DSPS) and adaptation to shift work.

Characterization of 16S rRNA genes from oil field microbial communities indicates the presence of a variety of sulfate-reducing, fermentative, and sulfide-oxidizing bacteria.

Oil field bacteria were characterized by cloning and sequencing of PCR-amplified 16S rRNA genes. A variety of gram-negative, sulfate-reducing bacteria was detected (16 members of the family Desulfovibrionaceae and 8 members of the family Desulfobacteriaceae). In contrast, a much more limited number of anaerobic, fermentative, or acetogenic bacteria was found (one Clostridium sp., one Eubacterium sp., and one Synergistes sp.). Potential sulfide oxidizers and/or microaerophiles (Thiomicrospira, Arcobacter, Campylobacter, and Oceanospirillum spp.) were also detected. The first two were prominently amplified from uncultured production water DNA and represented 28 and 47% of all clones, respectively. Growth on media containing sulfide as the electron donor and nitrate as the electron acceptor and designed for the isolation of Thiomicrospira spp. gave only significant enrichment of the Campylobacter sp., which was shown to be present in different western Canadian oil fields. This newly discovered sulfide oxidizer may provide a vital link in the oil field sulfur cycle by reoxidizing sulfide formed by microbial sulfate or sulfur reduction.

Chronobiotics--drugs that shift rhythms.

A chronobiotic is defined and levels of action within the mammalian circadian pacemaker system, such as the retina, retinohypothalamic tract, geniculohypothalamic tract, suprachiasmatic nuclei, output and feedback systems are identified. Classes of drug that include the indoleamines, cholinergic agents, peptides, and benzodiazepines, which might act as chronobiotics within these levels, are evaluated. Particular emphasis is placed on the indole, melatonin (MLT). The clinical circumstances for use of chronobiotics in sleep disturbances of the circadian kind, such as jet lag, shift work, delayed sleep-phase syndrome, advanced sleep-phase syndrome, irregular and non-24-hr sleep-wake cycles, are described under reorganized headings of disorders of entrainment, partial entrainment, and desynchronization. Specific attention is given to the blind and the aged. Both human and animal studies suggest that MLT has powerful chronobiotic properties. MLT shows considerable promise as a prophylactic and therapeutic alternative or supplement to the use of natural and artificial bright light for resetting the circadian pacemaker. Throughout this discussion, the hypnotic and hypothermic versus the chronobiotic actions of MLT are raised. Finally, problems in the design of delivery systems for MLT are discussed.

Overnight human plasma melatonin, cortisol, prolactin, TSH, under conditions of normal sleep, sleep deprivation, and sleep recovery.

Early investigations of the effect of sleep deprivation on plasma melatonin reported no major changes. Recently, 36 hrs of sleep deprivation was reported to elevate melatonin levels on the post-sleep deprivation night. Given these contradictions melatonin, cortisol, prolactin, and thyroid stimulating hormone before, during, and, after sleep deprivation were examined in nine healthy young males following one night of sleep deprivation. Hormone levels at hourly intervals, for each night, were statistically analyzed by a repeated measures, two-way factorial ANOVA. ANOVA was also performed for measures of area under the curve (AUC). No significant differences were observed for melatonin levels. Cortisol was significantly higher on the sleep deprivation night presumably reflecting the aroused state accompanying being awake; however, there were several time points on the control night when it was elevated also. Prolactin was higher on the post-sleep deprivation and control nights but did not rise on the deprivation night, indicating a useful nonpolysomnographic index for discriminating overnight sleep and awake states. TSH levels showed a similar rise during the control and sleep deprivation nights, but remained flat on the post-sleep deprivation night. It appears that the pineal is insulated against feedback from changes to the level of arousal accompanying sleep and wakefulness. In comparison, cortisol, prolactin, and TSH levels vary with these states and are, therefore, useful indices of arousal and sleep-wake.

Dose dependent effects of S-20098, a melatonin agonist, on direction of re-entrainment of rat circadian activity rhythms.

The chronobiotic properties of melatonin are well documented. For example, following an 8-h phase advance of the light-dark cycle daily injections of melatonin administered at the pre-shift dark onset alter the direction of re-entrainment of rat activity rhythms. Using this 8-h phase advance paradigm, the effects of the melatonin agonist S-20098 (1 mg/kg and 3 mg/kg) on the rat circadian system were compared with those of melatonin. S-20098 altered the direction of re-entrainment in the same manner as melatonin. A study using lower doses of S-20098 showed that the effect on direction of re-entrainment was dose-dependent, with 100% of rats responding at a dose of 100 micrograms/kg. S-20098 may, therefore, have therapeutic potential as a chronobiotic in the treatment of circadian disorders in humans.