The analysis of repeated measures designs in medical research

Automatic intensity windowing of mammographic images based on a perceptual metric

PURPOSE

Initial auto-adjustment of the window level WL and width WW applied to mammographic images. The proposed intensity windowing (IW) method is based on the maximization of the mutual information (MI) between a perceptual decomposition of the original 12-bit sources and their screen displayed 8-bit version. Besides zoom, color inversion and panning operations, IW is the most commonly performed task in daily screening and has a direct impact on diagnosis and the time involved in the process.

METHODS

The authors present a human visual system and perception-based algorithm named GRAIL (Gabor-relying adjustment of image levels). GRAIL initially measures a mammogram's quality based on the MI between the original instance and its Gabor-filtered derivations. From this point on, the algorithm performs an automatic intensity windowing process that outputs the WL/WW that best displays each mammogram for screening. GRAIL starts with the default, high contrast, wide dynamic range 12-bit data, and then maximizes the graphical information presented in ordinary 8-bit displays. Tests have been carried out with several mammogram databases. They comprise correlations and an ANOVA analysis with the manual IW levels established by a group of radiologists. A complete MATLAB implementation of GRAIL is available at https://github.com/TheAnswerIsFortyTwo/GRAIL.

RESULTS

Auto-leveled images show superior quality both perceptually and objectively compared to their full intensity range and compared to the application of other common methods like global contrast stretching (GCS). The correlations between the human determined intensity values and the ones estimated by our method surpass that of GCS. The ANOVA analysis with the upper intensity thresholds also reveals a similar outcome. GRAIL has also proven to specially perform better with images that contain micro-calcifications and/or foreign X-ray-opaque elements and with healthy BI-RADS A-type mammograms. It can also speed up the initial screening time by a mean of 4.5 s per image.

CONCLUSIONS

A novel methodology is introduced that enables a quality-driven balancing of the WL/WW of mammographic images. This correction seeks the representation that maximizes the amount of graphical information contained in each image. The presented technique can contribute to the diagnosis and the overall efficiency of the breast screening session by suggesting, at the beginning, an optimal and customized windowing setting for each mammogram.

Emulsified isoflurane postconditioning produces cardioprotection against myocardial ischemia-reperfusion injury in rats

Emulsified isoflurane (EIso) preconditioning can induce cardioprotection. We investigated whether EIso application after ischemia protects hearts against reperfusion injury and whether it is mediated by the inhibition of apoptosis. Rats were subjected to 30-min coronary occlusion followed by 180-min reperfusion. At the onset of reperfusion, rats were intravenously administered saline (sham, control group), 30 % intralipid (IL group) or 2 ml kg(-1) EIso (EIso group) for 30 min. After reperfusion, infarct sizes, myocardial apoptosis and expression of Bcl-2, Bax and caspase-3 proteins were determined. Hemodynamic parameters were not different among groups. Compared with control and intralipid group, EIso limited infarct size, inhibited apoptosis, increased the expression of Bcl-2, decreased the expression of Bax, cleaved caspase-3, and enhanced Bcl-2/Bax ratio. EIso protects hearts against reperfusion injury when administered at the onset of reperfusion, which may be mediated by the inhibition of apoptosis via modulation of the expression of pro- and anti-apoptotic proteins.

Teaching resuscitation in schools: annual tuition by trained teachers is effective starting at age 10. A four-year prospective cohort study

AIMS

Evaluation of school pupils' resuscitation performance after different types of training relative to the effects of training frequency (annually vs. biannually), starting age (10 vs. 13 years) and facilitator (emergency physician vs. teacher).

METHODS

Prospective longitudinal study investigating 433 pupils in training and control groups. Outcome criteria were chest compression depth, compression frequency, ventilation volume, ventilation frequency, self-image and theoretical knowledge. In the training groups, 251 pupils received training annually or biannually either from emergency physicians or CPR-trained teachers. The control group without any training consisted of 182 pupils.

RESULTS

Improvements in training vs. control groups were observed in chest compression depth (38 vs. 24 mm), compression frequency (74 vs. 42 min(-1)), ventilation volume (734 ml vs. 21 ml) and ventilation frequency (9/min vs. 0/min). Numbers of correct answers in a written test improved by 20%, vs. 5% in the control group. Pupils starting at age 10 showed practical skills equivalent to those starting at age 13. Theoretical knowledge was better in older pupils. Self-confidence grew in the training groups. Neither more frequent training nor training by emergency physicians led to better performance among the pupils.

CONCLUSIONS

Pupils starting at age 10 are able to learn cardiopulmonary resuscitation with one annual training course only. After a 60-min CPR-training update, teachers are able to provide courses successfully. Early training reduces anxieties about making mistakes and markedly increases participants' willingness to help. Courses almost doubled the confidence of pupils that what they had learned would enable them to save lives.

Bradygastric activity of the stomach predicts disgust sensitivity and perceived disgust intensity

The aim of this study was to investigate gastric and non-gastric autonomic responses to disgusting pictures and to assess the relationship between autonomic changes, disgust sensitivity, and perceived disgust intensity. Healthy participants viewed pictures with affectively neutral or disgusting content of either a high or moderate arousal level. Electrogastrogram, electrocardiogram, and electrodermal activity were recorded, and participants' disgust sensitivity and disgust intensity were assessed. No main effect of condition on gastric myoelectrical activity was found. However, stepwise regression analyses indicated that the percentage of bradygastria predicted disgust ratings in case of the highly arousing disgust pictures. When moderately arousing pictures were shown, disgust ratings were predicted by disgust sensitivity, which in turn was predicted by the percentage of bradygastria. Heart periods and respiratory sinus arrhythmia increased to a similar extent during both the highly arousing and moderately arousing picture blocks, while a tendency for larger skin conductance responses during the highly arousing picture block was shown. The results suggest that feelings of disgust may be specifically related to increased bradygastria, which may represent a prodromal sign of vomiting.

Peri-ictal normalization of visual cortex excitability in migraine: an MEG study

To delineate if the change in cortical excitability persists across migraine attacks, visual evoked magnetic fields (VEF) were measured in patients with migraine without aura during the interictal (n = 26) or peri-ictal (n = 21) periods, and were compared with 30 healthy controls. The visual stimuli were checkerboard reversals with four different check sizes (15', 30', 60' and 120'). For each check size, five sequential blocks of 50 VEF responses were recorded to calculate the percentage change of the P100m amplitude in the second to the fifth blocks in comparison with the first block. At check size 120', interictal patients showed a larger amplitude increment than controls [28.1 +/- 38.3% (s.d.) vs. 8.7 +/- 21.3%] in the second block and a larger increment than peri-ictal patients in the second (28.1 +/- 38.3% vs. -3.2 +/- 19.2%), fourth (22.7 +/- 31.2% vs. -5.7 +/- 22.3%) and fifth (20.5 +/- 30.4% vs. -10.8 +/- 30.1%) blocks (P < 0.05). There was no significant difference at other check sizes or between peri-ictal patients and controls. In conclusion, there may be peri-ictal normalization of visual cortical excitability changes in migraine that is dependent on the spatial frequency of the stimuli and reflects a dynamic modulation of cortical activities.

Different types of nutritional deficiencies affect different domains of spatial memory function checked in a radial arm maze

Several studies using animal models have suggested that the effects of nutritional insult on the developing brain are long-lasting and lead to permanent deficits in learning and behavior. Malnutrition can refer to the availability of all the nutrients but in insufficient quantities or it may imply that one or more of essential nutrients is either missing or is present, but in the wrong proportions in the diet. The hypothesis addressed in this study is that different domains of cognitive functioning can be affected by malnutrition and this can be related to the type of nutritional deficiency that the brain has been exposed to during development. To study the effect of nutritional deprivation during brain development, a paradigm of maternal malnutrition during the period of gestation and lactation was used and its effects were studied on the F1 offspring using Swiss albino mice. Three different types of malnutrition were used, that involve, caloric restriction, inadequate amount of protein in the diet and condition of low iron content. Our results show that the domain of spatial memory affected in the F1 generation depended on the kind of malnutrition that the mother was subjected to. Further our study shows that although hippocampal volume was reduced in all F1 pups, hippocampal subregions of the F1 animals were differentially vulnerable depending on type of malnutrition that the mother was subjected to. These results highlight the importance of qualifying the kind of malnutrition that is suffered by the mother during the period of gestation and lactation as it has consequences for the cognitive domain affected in the offspring. Awareness of this should inform prevention strategies in trying to reverse the effects of adverse maternal nutrition during critical periods in brain development.

Telephonic Remote Evaluation of Neuropsychological Deficits (TREND): longitudinal monitoring of elderly community-dwelling volunteers using touch-tone telephones

Use of interactive voice response (IVR) technology to monitor cognitive functioning in cognitively normal (CN), mild cognitive impairment (MCI), and mild dementia (MD) participants was examined using 107 community-dwelling participants, 65 to 88 years old. Baseline Clinical Dementia Ratings identified 36 participants as CN, 37 with MCI, and 34 as MD. Alzheimer's Disease Assessment Scale (ADAS) and Mini-Mental State Examinations were administered during clinic visits at weeks 0, 8, 16, and 24. IVR cognitive testing was completed at each visit and from participants' homes at weeks 4, 12, and 20. Study partners provided dementia symptoms severity ratings via IVR. The assessment system received 719 participant and 723 partner calls. All calls initiated by CN participants, 99.2% by MCI participants, and 87.3% by MD participants were completed. Telephonic Remote Evaluation of Neuropsychological Deficit tasks showed significant performance differences between participant groups, good reliability, and convergent validity with Mini-Mental State Examinations and ADAS-Cog measures. Automated cognitive testing calls took about 18 minutes to complete, and informant calls took approximately 4 minutes. IVR informant data were convergent with the ADAS-Noncog measure. Computer-automated assessments of cognitive functioning via IVR provided reliable, valid data. Such assessments might benefit routine clinical care and large-scale, longitudinal research in the future, but will require additional research over longer periods.

Melatonin prevents learning disorders in brain-lesioned newborn mice

Perinatal brain injuries often result in irreversible learning disabilities, which manifest in early childhood. These injuries are chiefly ascribable to marked susceptibility of the immature brain to glutamate-induced excitotoxicity. No treatments are available. One well-characterized model of perinatal brain injuries consists in injecting the glutamate analog ibotenate into the brain of 5-day-old mice. The resulting excitotoxic lesions resemble the hypoxic-ischemic gray-matter lesions seen in full-term and near-term newborns, as well as the white-matter lesions of preterm newborns. We previously reported that these lesions disrupted odor preference conditioning in newborn mice. The aim of this study was to assess the effectiveness of the neuroprotector melatonin in preventing learning disabilities in newborn mice with ibotenate-induced brain injury. In postnatal day (P) 6-P7 pups, we tested psychomotor reflexes, spontaneous preference for maternal odors as an index of memory, ultrasonic vocalization responses to stroking as an index of sensitivity to tactile stimuli, and conditioned preference for an odor previously paired with stroking as an index of learning abilities. Without melatonin, conditioning was abolished, whereas spontaneous odor preference, psychomotor reflexes, and sensitivity to tactile stimuli were normal. Thus, abolition of conditioning was not associated with sensorimotor impairments. Histological analysis confirmed the efficacy of melatonin in reducing white-matter lesions induced by ibotenate. Furthermore, treatment with melatonin protected the ability to develop conditioning. Thus, melatonin, which easily crosses the blood-brain barrier and has been proven safe in children, may be effective in preventing learning disabilities caused by perinatal brain injuries in human preterm infants.

Treatment-induced prevention of learning deficits in newborn mice with brain lesions

Perinatal brain injuries often result in irreversible learning disabilities, which manifest in early childhood. The molecular and cellular mechanisms of these injuries and potential pharmacological treatments are emerging, chiefly from studies in newborn rodents. In newborn mice, experimentally induced lesions can be dramatically reduced by appropriate neuroprotective treatments. However, the early effectiveness of these treatments in preserving cognition remained unknown. Here, we addressed this issue by using intracerebral ibotenate to induce excitotoxic brain lesions in 5-day-old mice (postnatal day 5). On postnatal days 6-7, we tested spontaneous preference for maternal odors, as an index of odor memory, and conditioned preference for an artificial odor previously paired with stroking, as an index of associative learning. Brain-lesioned newborn mice showed normal general status and preference for maternal odors. In contrast, odor conditioning was severely impaired. A previous study showed that fructose 1,6-biphosphate acted as a neuroprotective agent which significantly reduced neocortical lesion size. In the present study, treating the newborn mice with fructose 1,6-biphosphate 15 min before the ibotenate injection reduced neocortical lesion size and restored conditioning. This demonstrates, for the first time, that neuroprotective treatment can protect some features of early cognition.

Ventilatory response to hyperoxia in newborn mice heterozygous for the transcription factor Phox2b

Heterozygous mutations of the transcription factor PHOX2B have been found in most patients with central congenital hypoventilation syndrome, a rare disease characterized by sleep-related hypoventilation and impaired chemosensitivity to sustained hypercapnia and sustained hypoxia. PHOX2B is a master regulator of autonomic reflex pathways, including peripheral chemosensitive pathways. In the present study, we used hyperoxic tests to assess the strength of the peripheral chemoreceptor tonic drive in Phox2b+/-newborn mice. We exposed 69 wild-type and 67 mutant mice to two hyperoxic tests (12-min air followed by 3-min 100% O2) 2 days after birth. Breathing variables were measured noninvasively using whole body flow plethysmography. The initial minute ventilation decrease was larger in mutant pups than in wild-type pups: -37% (SD 13) and -25% (SD 18), respectively, P<0.0001. Furthermore, minute ventilation remained depressed throughout O2 exposure in mutants, possibly because of their previously reported impaired CO2 chemosensitivity, whereas it returned rapidly to the normoxic level in wild-type pups. Hyperoxia considerably increased total apnea duration in mutant compared with wild-type pups (P=0.0001). A complementary experiment established that body temperature was not influenced by hyperoxia in either genotype group and, therefore, did not account for genotype-related differences in the hyperoxic ventilatory response. Thus partial loss of Phox2b function by heterozygosity did not diminish the tonic drive from peripheral chemoreceptors.

Sleep-disordered Breathing in Newborn Mice Heterozygous for the Transcription Factor Phox2b

RATIONALE

Central congenital hypoventilation syndrome (CCHS) is a rare autosomal dominant syndrome present from birth, and characterized by depressed ventilation during sleep. Heterozygous mutations of the homeobox gene Phox2b were recently found in a very high proportion of patients.

OBJECTIVES

To determine whether newborn mice with heterozygous targeted deletion of the transcription factor Phox2b would display sleep-disordered breathing.

METHODS

We measured breathing pattern using whole-body plethysmography in wild-type and mutant 5-day-old mice, and we classified sleep-wake states using nuchal EMG and behavioral scores.

RESULTS

We found that sleep apnea total time was approximately six times longer (8.9 +/- 12 vs. 1.5 +/- 2.2 seconds, p < 0.0015), and ventilation during active sleep was 21% lower (18.4 +/- 5.1 vs. 23.3 +/- 5.5 ml/g/second, p < 0.006) in mutant than in wild-type pups. During wakefulness, apnea time and ventilation were not significantly different between mutant and wild-type pups. Mutant and wild-type pups showed highly similar sleep-wake states.

CONCLUSION

Although their respiratory phenotype was much less severe than CCHS, the Phox2b(+/-) mutant mice showed sleep-disordered breathing, which partially modeled the key feature of CCHS.

Olfactory classical conditioning in newborn mice

Determining the behavioural phenotype of genetically altered mice is a valuable approach for elucidating the function of genes and their role in cognitive disorders. Methods for phenotyping newborn mice are scarce and generally confined to sensorimotor reflexes. Here, we describe a simple method for assessing associative abilities in newborn mice. We used a two-odour-choice classical conditioning paradigm in mice from the day of birth (post-natal age 0, P0) to P6. Acquisition required 20 trials: 10 trials during which the pups were placed over the conditioned stimulus (CS+) odour (lemon or peppermint) for 30s and simultaneously stroked gently with a paintbrush and 10 trials during which the pups were placed over the other odour (CS-) for 30s, without stroking. Then, the pups were subjected to five odour-preference trials to test for conditioning. This sequence of five trials was repeated after 5 and 24h to assess retention of the conditioned odour preference. During the immediate post-acquisition sequence, the pups spent significantly more time over the CS+ than over the CS- (p<0.0001). No extinction of the conditioned preference was observed during this test. No preference was observed after 5 or 24h, indicating that the conditioned response was promptly lost. Conditioning was effective as soon as P0-P1. Thus, conditioning may emerge in newborn mice sooner than previously reported. This paradigm is well suited to phenotyping of large samples of genetically altered mice and may shed light on the role for genes in paediatric cognitive impairments.

Control of breathing in newborn mice lacking the beta-2 nAChR subunit

AIM

To study the ventilatory and arousal/defence responses to hypoxia in newborn mutant mice lacking the beta2 subunit of the nicotinic acetylcholine receptors.

METHODS

Breathing variables were measured non-invasively in mutant (n = 31) and wild-type age-matched mice (n = 57) at 2 and 8 days of age using flow barometric whole-body plethysmography. The arousal/defence response to hypoxia was determined using behavioural criteria.

RESULTS

On day 2, mutant pups had significantly greater baseline ventilation (16%) than wild-type pups (P < 0.02). Mutant pups had a decreased hypoxic ventilatory declines. Arousal latency was significantly shorter in mutant than in wild-type pups (133 +/- 40 vs. 146 +/- 20 s, respectively, P < 0.026). However, the duration of movement elicited by hypoxia was shorter in mutant than in wild-type pups (14.7 +/- 5.9 vs. 23.0 +/- 10.7 s, respectively, P < 0.0005). Most differences disappeared on P8, suggesting a high degree of functional plasticity.

CONCLUSION

The blunted hypoxic ventilatory decline and the shorter arousal latency on day 2 suggested that disruption of the beta2 nicotinic acetylcholine receptors impaired inhibitory processes affecting both the ventilatory and the arousal response to hypoxia during postnatal development.

Intermittent hypoxia induces transient arousal delay in newborn mice

Previous studies suggested that defective arousal might be a major mechanism in sleep-disordered breathing such as sudden infant death syndrome and obstructive sleep apnea. In this study, we examined the effects of intermittent hypoxia (IH) on the arousal response to hypoxia in 4-day-old mice. We hypothesized that IH would increase arousal latency, as previously reported in other species, and we measured the concomitant changes in ventilation to shed light on the relationship between breathing and arousal. Arousal was scored according to behavioral criteria. Breathing variables were measured noninvasively by use of whole-body flow plethysmography. In the hypoxic group ( n = 14), the pups were exposed to 5% O2 in N2 for 3 min and returned to air for 6 min. This test was repeated eight times. The normoxic mice ( n = 14) were constantly exposed to normoxia. The hypoxic mice showed a 60% increase in arousal latency ( P < 0.0001). Normoxic controls showed virtually no arousals. IH depressed normoxic ventilation below baseline prehypoxic levels, while preserving the ventilatory response to hypoxia. The breathing pattern and arousal responses recovered fully after 2 h of normoxia. We conclude that IH rapidly and reversibly depressed breathing and delayed arousal in newborn mice. Both effects may be due to hypoxia-induced release of inhibitory neurotransmitters acting concomitantly on both functions.

Assessing problems with religious content: a comparison of rabbis and psychologists

This study measured distinctions made by a sample of clergy and mental health professionals in response to three categories of presenting problems with religious content: mental disorder, religious or spiritual problem, and "pure" religious problem. A national, random sample of rabbis (N = 111) and clinical psychologists (N = 90) provided evaluations of three vignettes: schizophrenia, mystical experience, and mourning. The participants evaluated the religious etiology, helpfulness of psychiatric medication, and seriousness of the presenting problems. The rabbis and psychologists distinguished between the three diverse categories of presenting problems and concurred in their distinctions. The results provide empirical evidence for the construct validity of the new DSM-IV category religious or spiritual problem (V62.89). Use of the V code allows for more subtle distinctions among the variety of problems that persons bring to clergy and mental health professionals. These distinctions may also provide a foundation for the initiation of co-professional consultation.

Effects of prolonged oral reading on F0, SPL, subglottal pressure and amplitude characteristics of glottal flow waveforms

The effects of prolonged (5x45 minute) reading (vocal loading) on fundamental frequency (F0), sound pressure level (SPL), subglottal (intraroral) pressure (p), and two glottal flow waveform parameters (AC amplitude of glottal flow, f, and negative peak amplitude of differentiated flow (d) of normal female and male subjects (N = 80) were studied. Two rest (morning and noon) and three loading (two in the morning and one in the afternoon) samples were recorded and analyzed. The glottal waveforms were obtained by inverse filtering of the acoustic pressure waveforms of speaking voice samples. The analyses were based on measurement and inverse filtering of the first stressed syllable of "paappa" words repeated 3x5 times for normal, as soft as possible, and as loud as possible phonation. In normal phonation the parameter values changed statistically significantly due to loading. In many cases the values obtained in the morning samples changed after the first loading session. This is interpreted as a vocal "warming-up effect." Especially in soft phonation p, d, and f were sensitive indicators of vocal loading. In both normal and soft phonation, the SPL, p, d, and f values tended to rise due to prolonged reading in the morning and afternoon samples, indicating increased effort (normal phonation) and a rise in the phonatory threshold (soft phonation). The lunch break vocal rest ("rest effect") considerably affected the parameter values in many cases.

Enalaprilat controls postoperative hypertension while maintaining cardiac function and systemic oxygenation after neurosurgery

OBJECTIVE

The efficacy of intravenous enalaprilat in lowering postoperative hypertension.

DESIGN

Prospective, randomized, controlled, single blind trial.

SETTING

Surgical ICT in a university hospital (tertiary care center).

PATIENTS

18 neurosurgical patients subjected to the extirpation of a supratentorial intracerebral tumour were studied after detection of postoperative hypertension. This was defined as a constant elevation of systolic arterial pressure over 160 mmHg or diastolic arterial pressure over 95 mmHg.

INTERVENTIONS

Enalaprilat 0.015 mg kg-1 was injected within 5 min to 9 patients.

MEASUREMENTS AND RESULTS

Central haemodynamics and systemic oxygenation were assessed at baseline before enalaprilat injection, and repeatedly during four hours after the injection. The statistical analysis was performed with analysis of variance for repeated measurements. As compared to control patients, the blood pressure lowering effect of enalaprilat became evident within 15 min and lasted for over four hours (p = 0.008). It was mainly due to the reduced systemic vascular resistance. Enalaprilat also induced a small decline in myocardial perfusion pressure. Cardiac performance, preload, heart rate and systemic oxygenation were not affected by enalaprilat.

CONCLUSIONS

We found intravenous enalaprilat effective and safe in lowering postoperative hypertension following neurosurgery as assessed by it's effects on central haemodynamics and systemic oxygenation.

Pharmacokinetic analysis of coronary venous retroinfusion: a comparison with anterograde coronary artery drug administration using metoprolol as a tracer

Plasma and myocardial tissue concentrations of metoprolol were studied in ischemic and nonischemic areas of 22 pigs after 90 (n = 19) and 16 (n = 3) min of left anterior descending coronary artery occlusion. Group A (n = 6) received simultaneous intravenous metoprolol (0.2 mg/kg body weight) and tritium-labeled (3H)-metoprolol (0.2 mg/kg) retrogradely into the coronary vein. In group B (n = 5), metoprolol and 3H-metoprolol were administered in the same way, but at half the volume to study the influence of derived coronary venous pressure on the myocardial concentration of drug. In group C (n = 3), metoprolol was given retrogradely and saline solution was infused into the left anterior descending artery before induced death to wash out metoprolol from the coronary veins. To rule out a possible influence of the development of myocardial necrosis on drug distribution, metoprolol was retroinfused after 1 min of arterial occlusion in three pigs (group D). In group E (n = 5), metoprolol (0.2 mg/kg) was infused anterogradely into the left anterior descending artery. Peak plasma concentration was significantly higher after intravenous infusion of metoprolol (1,188 +/- 503 nmol/liter) than after coronary venous infusion (417 +/- 155 nmol/liter; p less than 0.001). In groups A and B, the nonischemic myocardial concentration of metoprolol was 250 to 300 pmol/g, whether the drug was infused intravenously or into the coronary vein. Coronary venous retroinfusion, however, resulted in a substantial accumulation of metoprolol in the ischemic myocardium. In group A pigs, subendocardial myocardial concentration was 16,800 +/- 7,774, mid-myocardial 39,590 +/- 18,043 and subepicardial 57,143 +/- 29,030 pmol/g (mean +/- SE). The ischemic myocardial concentration in pigs from group B was somewhat less pronounced, probably secondary to a lower coronary venous pressure (15 +/- 3 mm Hg) with the lower volume of infusion (6.1 +/- 0.3 ml) in group B compared with 32 +/- 5 mm Hg with a 14 +/- 1 ml infusion in group A. Coronary artery anterograde administration resulted in myocardial ischemic and nonischemic zone drug concentrations similar to those observed after retroinfusion into the coronary vein. With both modes of administration, there was a transmyocardial gradient from a somewhat lower drug concentration in the subendocardium, toward an increasing level in the mid-myocardium, to the highest concentration in the subepicardial zone of the ischemic myocardium. Coronary venous retroinfusion resulted in pronounced drug accumulation in the ischemic myocardium. The derived coronary venous pressure during infusion influenced the concentration of drug.(ABSTRACT TRUNCATED AT 400 WORDS)

Multiple regression analysis of differential response to treatment in randomized controlled clinical trials

A multiple regression model is presented for the analysis of the components of individual change in clinical trials. Of primary interest is the condition where treatment effects vary according to patient baseline level. The model differentiates the average effects of treatment from baseline-dependent treatment effects, as well as identifying regression toward the mean and temporal effects. This model is applied in the analysis of data from a clinical trial of nutritional supplementation.

Intramuscular dexmedetomidine, a novel alpha 2-adrenoceptor agonist, as premedication for minor gynaecological surgery

The effects of three different doses (0.5, 1.0 and 1.5 micrograms/kg) of dexmedetomidine, a novel alpha 2-adrenoceptor agonist, on vigilance, anaesthetic requirements, haemodynamics, and plasma catecholamine levels were investigated in a double-blind placebo-controlled study in 20 healthy (ASA physical status I-II) women scheduled for uterine dilatation and curettage (UD&C). The drug was administered intramuscularly 60 min before induction of anaesthesia with thiopentone, N2O/O2 (70/30%) and thiopentone was used for maintenance. There were no significant differences between the groups in thiopentone requirements, plasma adrenaline concentrations, or subjective or objective assessment of sedation before anaesthesia and UD&C. Blood pressure, heart rate, and plasma noradrenaline levels were reduced after dexmedetomidine, with three patients receiving atropine for excessive bradycardia (less than 45 beats min-1). The haemodynamic as well as the sedative effects of dexmedetomidine after surgery lasted until the end of the observation period, 4 h after the injection of the drug, indicating that intramuscular administration of this premedication agent may result in a longer than optimal duration of pharmacological actions in connection with short surgical procedures.

Rapid reversal of alpha 2-adrenoceptor agonist effects by atipamezole in human volunteers

1. The ability of atipamezole, a specific and selective alpha 2-adrenoceptor antagonist, to reverse the pharmacological effects induced by the alpha 2-adrenoceptor agonist dexmedetomidine was studied in six healthy male volunteers. Each volunteer received in four sessions in a randomized and single-blind manner three different doses (6.7 micrograms kg-1, 27 micrograms kg-1 and 67 micrograms kg-1) of atipamezole or saline placebo as 5 min i.v. infusions preceded by a fixed i.v. dose of dexmedetomidine (0.67 micrograms kg-1). 2. Dexmedetomidine caused profound sedation, with the subjects actually falling asleep. This was effectively reversed by the two highest doses of antipamezole. 3. Dexmedetomidine reduced salivary flow on average by 70%. A rapid and full reversal of this effect was seen after the highest dose of antipamezole. 4. Hypotension induced by dexmedetomidine was also effectively antagonized by atipamezole. Bradycardia was very modest after dexmedetomidine in this study, and thus no reversal of alpha 2-adrenoceptor agonist-induced bradycardia could be demonstrated. 5. Plasma noradrenaline concentrations were reduced by 80% by dexmedetomidine. This was effectively antagonized by atipamezole, and the highest dose caused a 50% overshoot in plasma noradrenaline concentrations over the basal levels. 6. It is concluded that the effects of dexmedetomidine are effectively reversible by atipamezole. A dose ratio of 10:1 for atipamezole:dexmedetomidine was clearly insufficient for this purpose, but ratios in the range of 40:1 to 100:1 were found to be effective in the current experimental situation.

Pharmacological effects and pharmacokinetics of atipamezole, a novel alpha 2-adrenoceptor antagonist--a randomized, double-blind cross-over study in healthy male volunteers

1. Single doses (10, 30 and 100 mg) of atipamezole (MPV-1248), a new potent and selective imidazole-type alpha 2-adrenoceptor antagonist, and saline placebo were administered as 20 min intravenous infusions to six healthy male volunteers in a randomized double-blind, cross-over phase I study. Later, 100 mg atipamezole was given orally to the same subjects in an open fashion. 2. The i.v. doses resulted in linearly dose-related concentrations of atipamezole in plasma. Pharmacokinetic calculations revealed an elimination half-life of 1.7-2.0 h, an apparent volume of distribution of 3.0-3.5 l kg-1 and a total plasma clearance of 1.1-1.5 l h-1 kg-1. No atipamezole could be detected in plasma after oral dosing. 3. Subjective drug effects were seen mainly after the largest i.v. dose and included increased alertness and nervousness, coldness and sweating of hands and feet, tremor and shivering, motor restlessness, and increased salivation. Salivation was also quantitated using dental cotton rolls, with dose-related increases produced by the i.v. doses. 4. The 100 mg i.v. dose increased plasma noradrenaline concentrations on average by 484 +/- 269 (s.d.)%, and also elevated both systolic and diastolic blood pressure (mean increases 17 +/- 7/14 +/- 2 mm Hg). The 30 mg dose had minor and the 10 mg dose no effects on these variables. Adrenaline and cyclic AMP levels in plasma were increased only after the largest dose. No drug effects were observed after oral dosing. 4. Plasma C-peptide and blood glucose levels were not markedly influenced by the drug, and cortisol secretion was not stimulated. 5. The observed effects are compatible with the presumed alpha 2-adrenoceptor antagonistic action of atipamezole and are in general concordance with the reported results of other alpha 2-adrenoceptor antagonists (yohimbine and idazoxan). 6. Although not orally active, atipamezole may prove to be a useful agent in studies of alpha 2-adrenoceptor function in man.

Flow velocity waveforms in uterine and umbilical arteries during the angiotensin II sensitivity test

The angiotensin II sensitivity test has been used to predict the development of hypertension during pregnancy. We investigated the systolic/diastolic ratios of flow velocity waveforms in the uterine and umbilical arteries by means of a color Doppler system in 15 healthy women at 24 to 26 weeks' gestation. A significant increase (p less than 0.001) was observed in the systolic/diastolic ratio in the uterine artery, which was unaffected by the location of the placenta. In five women a differential effect of angiotensin II on the systemic diastolic blood pressure and on the systolic/diastolic was observed: the uterine circulation appeared to have a slower response and a faster recovery than the diastolic blood pressure. No changes in the systolic/diastolic ratio in the umbilical artery were observed.

Inhibition of monoamine oxidase by moclobemide: effects on monoamine metabolism and secretion of anterior pituitary hormones and cortisol in healthy volunteers

1. Single oral doses (100, 200 and 300 mg) of moclobemide, a reversible inhibitor of monoamine oxidase (MAO) with predominant effects on the A-type of the enzyme, were administered to eight young, healthy male volunteers in a double-blind, random-order, placebo-controlled study. The investigation was thereafter continued in an open fashion by administering a single 10 mg dose of the MAO-B inhibitor deprenyl to the same subjects. 2. Deamination of catecholamines was powerfully and dose-dependently inhibited by moclobemide, as evidenced by up to 40% decreases in the urinary excretion of deaminated catecholamine metabolites, corresponding increases in the excretion of non-deaminated, methylated metabolites, and up to 79% average decreases in the plasma concentration of 3,4-dihydroxyphenylglycol (DHPG), a deaminated metabolite of noradrenaline (NA), and up to 75% average decreases in the plasma concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC), a deaminated metabolite of dopamine. The urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA) was only slightly reduced. In contrast, deprenyl, in a dose which almost totally inhibited MAO-B activity in blood platelets, did not appreciably affect the plasma concentrations of DHPG or DOPAC. 3. Due to the rapid, reversible, dose-dependent and MAO-A specific effect of moclobemide on plasma concentrations of DHPG, it is suggested that DHPG in plasma may be a useful indicator of the magnitude and duration of MAO-A inhibition in man. 4. Sympatho-adrenal function at rest was not significantly altered by moclobemide, as judged by unchanged plasma catecholamine concentrations and stable blood pressure and heart rate recordings. 5. Monoamine oxidase type B activity in blood platelets was slightly (less than 30%) and transiently inhibited after moclobemide. 6. The secretion of prolactin was dose-dependently stimulated by moclobemide, whereas the plasma concentrations of growth hormone (hGH) and cortisol remained unchanged.

Sedative and cardiovascular effects of medetomidine, a novel selective alpha 2-adrenoceptor agonist, in healthy volunteers

1. Single intravenous doses (25, 50 and 100 micrograms) of medetomidine (MPV-785, an imidazole derivative), a selective alpha 2-adrenoceptor agonist, were administered to eight healthy male volunteers in a double-blind, placebo-controlled study. 2. The following dose-related effects, all of which were compatible with an agonistic action of the drug at alpha 2-adrenoceptors, were noted: reductions of systolic and diastolic blood pressure (maximum 18/11 mm Hg), heart rate (maximum 10 beats min-1), saliva secretion (maximum 84%) and noradrenaline levels in plasma (maximum 70%). 3. Dose-dependent sedation or impairment of vigilance was also observed, both by subjective and objective (critical flicker fusion threshold) assessments, with the highest dose actually inducing sleep in five of the subjects. 4. The observed effects were in general agreement with those previously seen after intravenous administration of the centrally acting antihypertensive alpha 2-adrenoceptor activating drug, clonidine, but of a shorter duration. 5. The relative importance of alpha 2-adrenoceptors located in peripheral tissues and in the central nervous system for the drug's cardiovascular effects could not be determined, but the high lipid solubility of the compound and the rapid onset of sedation are in favour of a major central component. 6. Medetomidine may be a useful tool for the investigation of the physiology and pharmacology of alpha 2-adrenoceptors in man. In addition, the therapeutic and diagnostic uses of the compound should be investigated in pathological conditions related to increased sympathetic neuronal activity.