Laser-induced direct space-selective precipitation of CdS nanoparticles embedded in a transparent silica xerogel.

A simple method, suitable for direct space-selective precipitation of semiconducting nanoparticles inside a transparent silica xerogel, is presented. The porous silica monoliths, prepared by the sol-gel method, are first loaded with specific CdS precursors. Then, the samples can be irradiated using either a femtosecond laser to generate the nanoparticles inside the deep volume of the silica matrix or a continuous visible laser to yield a nanocrystal growth under the surface. The resulting CdS nanoparticles are characterized using absorption and Raman spectroscopies, x-ray diffraction analysis and transmission electron microscopy.

Understanding the basics of cannabidiol from cannabis to apply to therapeutics in epilepsy.

The compounds present in cannabis have been in use for both recreational and medicinal purposes for many centuries. Changes in the legislation in South Africa have led to an increase in the number of people interested in using these compounds for self-medication. Many of them may approach their general practitioner as the first source of information about possible therapeutic effects. It is important that medical professionals are able to give patients the correct information. Cannabidiol (CBD) is one of the main compounds in cannabis plants, and there is evidence that it can successfully treat certain patients with epilepsy. This review looks at the most recent evidence on the use of CBD in the treatment of epilepsy and explores the mechanisms behind these beneficial effects.

Cardiotoxic effects of pavetamine extracted from Pavetta harborii in the rat.

Previous studies have shown that crude extracts from Pavetta harborii as well as dried plant material have cardiotoxic effects on rats and sheep that can lead to heart failure. The active component has since been isolated and identified. This substance has been named pavetamine. The aim of this study was to determine whether pavetamine has cardiotoxic effects similar to those seen in previous reports, when administered to rats intraperitoneally. Sprague Dawley rats received two doses, initially 4 mg/kg and then 3 mg/kg pavetamine respectively and were monitored for 35 days before cardiodynamic parameters were measured by inserting a fluid-filled catheter into the left ventricle via the right carotid artery. These values were compared to those of control rats that had received only saline. Pavetamine significantly reduced systolic function and body mass in the treated rats, which indicates that it has the potential to induce heart failure in this animal model.

The dose-related hyper-and-hypokalaemic effects of salbutamol and its arrhythmogenic potential.

1. The hypokalaemic effect of salbutamol after more than 30 min of administration has been well described. A hyper-and-hypokalaemic effect for adrenaline has been reported, but no such hyperkalaemic effect for salbutamol. 2. The possible hyper-and-hypokalaemic effects of salbutamol with the concomitant potential for pro-arrhythmia were assessed in the baboon (Papio ursinus). 3. Male and female baboons were anaesthetized with ketamine (15 mg kg-1) and maintained with 6% pentobarbitone as spontaneously breathing animals. Six baboons in each group received either 10, 100 or 500 micrograms kg-1 salbutamol i.v. Lead II of the ECG and femoral i.a. blood pressure were recorded continuously for 10 min. Arterial blood samples were collected at 0 min and then after 3 and 10 min of salbutamol administration. 4. All the animals developed sinus tachycardia (above 200 beats min-1) within 30 s of each dose of salbutamol administration and the high heart rate persisted throughout the experiment. All the animals were hyperkalaemic after 3 min and hypokalaemic after 10 min for each dose of salbutamol. Left ventricular conduction defects were seen in 3 animals during the hyperkalaemic phase. No arrhythmia was seen during the hypokalaemic phase. 5. Salbutamol has a transient hyperkalaemic and a more prolonged hypokalaemic effect in the baboon. The hypokalaemia could not be associated with arrhythmia although conduction defects were associated with the hyperkalaemia. 6. Since salbutamol is used as a bronchodilator in asthmatic patients and to treat acute hyperkalaemia, it is suggested that caution should be exercised when using salbutamol in high doses to treat acute asthma especially during the first few minutes of administration. The finding of hyperkalaemia with salbutamol questions its use in the treatment of hyperkalaemia.

Age effects on reflex and postural responses to propriomuscular inputs generated by tendon vibration.

The effects of aging on two sensorimotor levels of propriomuscular function were investigated in a young (20- to 44-year-old) and an elderly (60- to 86-year-old) population by eliciting segmental reflex and postural responses via the same muscle spindle inflow generated by applying the same pattern of tendon vibration. The latency and amplitude of the reflex responses to vibration (tonic vibration reflex) of the biceps and triceps brachii did not depend on the subjects' age. No major age-related changes were observed in the deep reflexes of the lower limbs. The postural responses to the same vibratory stimulation applied to both the soleus or the tibialis anterior muscles (vibration-induced falling) did not show any changes in latency depending on either age or the visual conditions, whereas the intensity of these responses decreased both with age and when the use of vision was possible. Our results suggest that the two levels at which the same propriomuscular messages were processed are differentially affected by aging. The lower reflex level does not undergo any noticeable impairment, whereas the higher postural control level deteriorates in the elderly, which might be partly responsible for the balance problems which tend to occur more frequently with advancing age.

Some adverse cardiodynamic effects of prostaglandin E2 in congestive heart failure.

The cardiodynamic effects of prostaglandin E(2) (PGE(2)) were studied in both healthy sheep and in animals with congestive heart failure (CHF). Merino ewes were equipped surgically with high fidelity micromanometers and left ventricular pressures measured. Heart rate, left ventricular systolic and end-diastolic pressures, +dP/dt and T(ln) were calculated on a computer from the recorded pressure curves. The paired t-test was used to determine the statistical significance of the differences. PGE(2) (25 mu g/kg) significantly improved the cardiac contractility and relaxation rate of healthy sheep and significantly reduced the heart rate, while the loading conditions under which the heart operates were not significantly affected. In contrast to healthy sheep, PGE(2) significantly reduced the contractility and relaxation rate of sheep with congestive heart failure and significantly increased the preload while heart rate and afterload were significantly reduced. The study suggests that despite the promising vasodilatory, positive inotropic and relaxation rate actions of PGE(2) in normal hearts, PGE(2) might not be a suitable therapeutic agent for CHF, because of the worsening effect it has on the cardiodynamics and loading conditions of the failing heart.

The effect of chlamydial infection on the initiation of premature labour: serial measurements of intrauterine prostaglandin E2 in amniotic fluid, allantoic fluid and utero-ovarian vein, using catheterised sheep experimentally infected with an ovine abortion strain of Chlamydia psittaci.

The initiation of premature labour by an ovine abortion strain of Chlamydia psittaci was studied in relation to Prostaglandin E2 (PGE2), which plays a major role in parturition. The local intrauterine concentration of PGE2 was monitored after experimental infection with C. psittaci, during late gestation, using a catheterised sheep model. Indwelling catheters were implanted into the amniotic and allantoic cavities of six control sheep, and into six sheep infected with an ovine abortion of C. psittaci. The release of PGE2 into the utero-ovarian vein of these sheep was also monitored. Infection with C. psittaci was associated with a premature rise in PGE2 in the amniotic fluid between days 122 and 135 of gestation (P less than 0.01). A premature increase in PGE2 was defected between days 127 and 136 of gestation (P less than 0.05) in the allantoic fluid of sheep infected with C. psittaci, but not in the control uninfected sheep. Chlamydial infection significantly decreased the secretion of PGE2 into the utero-ovarian vein. The mean concentration of PGE2 in the utero-ovarian vein of infected sheep was 68.8 +/- 5.2% of the PGE2 concentration of control sheep between days 122 to 141 of gestation (P less than 0.01). The release of PGE2 into the utero-ovarian vein increased between days 126 to 136 of gestation in infected and control sheep (P less than 0.01). The results from the catheterised sheep model indicated that C. psittaci infection is associated with a local intrauterine release of PGE2. The magnitude of this release was similar to the PGE2 release in control sheep prior to parturition.(ABSTRACT TRUNCATED AT 250 WORDS)

Prophylactic use of human endotoxin-core hyperimmune gammaglobulin to prevent endotoxaemia in colostrum-deprived, gnotobiotic lambs challenged orally with Escherichia coli.

The efficacy of human IgG polyclonal antibody to endotoxin-core in preventing endotoxaemia and subsequent disease was studied in colostrum-deprived gnotobiotic lambs challenged orally at about 5 h old with 10(9) cfu Escherichia coli. Human endotoxin-core hyperimmune gammaglobulin was given intravenously to 5 lambs at 1.9 g IgG/kg bodyweight prior to challenge. Human albumin was given intravenously to 3 control lambs. Bacteraemia was observed in all lambs, but the incidence was lower (P < 0.01) and the onset later (P < 0.05) in gammaglobulin pre-treated lambs. These lambs showed no signs of disease, whereas clinical endotoxaemia, manifesting as watery mouth disease, was diagnosed in 2 of the 3 control lambs which were killed between 18 and 22 h after challenge. Thus, prophylactic treatment of colostrum-deprived lambs with human IgG enriched in endotoxin-core antibodies was effective in reducing the degree of bacteraemia and preventing endotoxaemia, leukopenia and clinical disease following oral challenge with E. coli.

Unrecognized hypo- and hyperglycemia in well-controlled patients with type 2 diabetes mellitus: the results of continuous glucose monitoring.

The aim of this study was to determine the prevalence and extent of glycemic excursions (hypo- and hyperglycemic) in elderly patients with well-controlled type 2 diabetes using a Continuous Glucose Monitor System (CGMS) (Medtronic MiniMed). Elderly patients (>65 years old) with type 2 diabetes were recruited if their glycosylated hemoglobin (HbA1c) was <7.5% and if their oral hypoglycemic therapy included a sulfonylurea. Patients were asked to undergo two consecutive 72-h periods of continuous glucose monitoring at baseline and then again at 1 month (total 288 h). Patients were asked to record four self-monitored capillary blood glucose levels each day for calibration of the monitor and also to record meal times, exercise, and symptoms of hypoglycemia. The number of hyperglycemic (>144 mg/dL), hypoglycemic (<50 mg/dL), and borderline-hypoglycemic (50-65 mg/dL) events were determined (an event was defined as a glucose value that persisted for at least 15 min with or without symptoms). Twenty-five patients (21 men, four women) 73.9 +/- 4.4 years old with an HbA1c of 6.2 +/- 0.8% were each monitored for an average of 187.57 h. The mean glucose values were: fasting, 139 +/- 40 mg/dL; 2 h post-breakfast, 167 +/- 58 mg/dL; 2 h post-lunch, 157 +/- 53 mg/dL; and 2 h post-dinner, 149 +/- 49 mg/dL. Twenty patients (80%) experienced a total of 103 hypoglycemic events, and 14 of these patients experienced 54 events where the glucose levels were 144 mg/dL 2 h postprandial) were recorded after 57% of all meals (breakfast 60%, lunch 57.5%, dinner 55.2%). The CGMS was generally well tolerated, but 52% of patients could not be studied for the full 12 days of monitoring. Thus hypoglycemia and excessive postprandial glycemic excursions are common in well-controlled patients with type 2 diabetes treated with a sulfonylurea with or without metformin. The CGMS is a useful research and clinical tool to assess glycemia in patients with type 2 diabetes but is not tolerated by all subjects.

ECT and tardive dyskinesia.

Three cases of elderly depressed patients with symptoms of tardive dyskinesia (TD) subsequently treated with electroconvulsive therapy (ECT) are presented. These cases are discussed in relation to several cases reported in the literature of ECT and TD. The possibility of improvement in symptoms of TD in certain patients is discussed.

Kinematics of aiming in direction and amplitude: a developmental study.

The patterns of aimed movements to visual targets were analyzed in children aged 6, 8 and 10. Tasks with direction and/or amplitude requirements were used. The tasks were performed both with and without vision. Peak velocity, acceleration and deceleration and their relative temporal occurrence were evaluated. Overall, the 6- and 10-year-olds exhibited higher peak velocity and acceleration when performing the pure directional task than when performing tasks with an amplitude or stopping requirement. On the contrary, 8-year-olds showed similar peak acceleration and velocity across all three tasks. Similarly, when performing the pure directional task, the 6- and 10-year-olds reached their peak velocity and acceleration relatively later in time than the 8-year-olds. Vision of movement increased the peak velocity in all experimental tasks and peak acceleration was increased only in the pure directional task. Thus, movement kinematics varied according to the task requirements and age. Eight-year-olds showed greater propensity to feedback control in all tasks, suggesting an over-inhibition in their approach patterns, whereas 10-year-olds tended to use feedforward processes, with a shortened deceleration phase.

The effect of amplitude and accuracy requirements on movement time in children.

The object of this study was to investigate how children control their movements, through- the analysis of Fitts' Law on subjects 5, 7, 9, and 11 yr of age. Children had to perform rapid alternative pointing movements between two targets, varying in width and distance (level of difficulty of the task). The analysis of movement time showed that, as children grow up, movement speed increased and was gradually less affected by the level of difficulty of a given task; moreover the respective effects of accuracy and amplitude requirements on movement time changed with age, resulting in distinct evolutive patterns. The results are thereby discussed in relation to the respective development of both programming and guiding components of movement in children. A few observations about ocular strategies during the task were also noted.

Spatial-temporal analysis of movements in children.

Hand-eye coordination was studied in 5-, 7-, 9-, and 11-yr-old children in order to test the hypothesis of an evolution in the relationship between the programming system and the guidance system in reaching movement. In the first experiment children had to perform open-loop movements (i.e., without seeing their hands towards visual targets as accurately as possible. The accuracy, time, speed, and patterns of movements were analyze second experiment the reach trajectories of the hand were analyzed in children wearing displacing prisms in order to measure the visually guided part of the trajectory. Charges in the spatial-temporal characteristics of open-loop reaching movements and in the amount of visual guided activity appear from the results. A predominance the programming system at 5 yr and guiding system at 7 yr, followed at 9 11 yr by integration of both systems, is discussed.

Proprioceptive control of goal-directed movements in man, studied by means of vibratory muscle tendon stimulation.

The purpose of this study was to investigate the role of propriomuscular feedback in the control of pluriarticular pointing movements, performed without visual feedback toward visual targets. The proprioceptive inputs were distorted during movements by applying vibration to the distal tendon of the biceps muscle. Various movement and vibration durations were imposed. The results show that vibration affects the spatial outcome of the movements. The effects of vibration were movement time-independent when the durations were shorter than 450 ms and became movement time-dependent with longer durations. Moreover, the effects of vibration became more marked when a short vibration was applied at the end rather than at the beginning of a slow movement. These studies suggest that at least two types of proprioceptive control loops may be involved in correcting this kind of movement, depending on the execution time. In slow movements, the final phase might be a privileged period for on-line, propriomuscular-based corrections. Lastly, it emerged that the regulation of a goal-directed movement on the basis of proprioceptive feedback processing can take place within at most 200 ms.

Resolving power of the perceptual- and sensorimotor systems in 6- to 10-year-old children.

Children aged 6 to 10 were tested on their ability to move accurately and to perceptually evaluate their motor response. Subjects performed a directional and an amplitude visuo-manual aiming task without vision of their moving limb. They were asked to correct their error, after completion of their movements, only if they felt they were not accurate. Terminal aiming errors and correction responses (adjustments) were analyzed, and threshold detection was determined relative to terminal aiming error. Action accuracy and evaluation of action accuracy are two abilities that do not develop synchronously. Moreover, the relationship between these abilities depends on whether accuracy and direction or amplitude are required. Amplitude undergoes more corrections than direction, suggesting that the spatial system of reference involved depends more upon the coding of the final position than on direction. Two spatial comparators, operating on the basis of two types of evaluation, seem to have a variably distinct contribution to movement and perception accuracy, according to age.

Immune exclusion of Haemonchus contortus larvae in sheep: dose dependency, steroid sensitivity and persistence of the response.

Naive and immune sheep, treated with anthelmintic, challenged directly into the abomasum and killed 48 hours later were used to examine the steroid sensitivity, persistence and dose dependency of immune mechanisms which result in the failure of incoming Haemonchus contortus larvae to establish (immune exclusion). Immune exclusion was almost totally abolished by corticosteroid treatment, the mean percentage of larvae establishing in the mucosa of immune sheep was 1.4 per cent of the challenge infection whereas in those treated with dexamethasone it was 24.4 per cent and in naive sheep 27.3 per cent. Immune animals challenged after seven and 42 days without antigenic experience excluded more than 90 per cent of the challenge larvae from their mucosae, whereas those challenged after 84 days without antigenic experience were as susceptible as naive animals. Immune exclusion was dose dependent, animals challenged with 10(6) and 10(5) larvae excluded 93 per cent and 82.5 per cent of the challenge dose whereas those challenged with 10(4) larvae failed to exclude larvae.

Biochemical and haematological evidence of endotoxic shock in gnotobiotic lambs with watery mouth disease.

Eight gnotobiotic lambs deprived of colostrum were infected by mouth when two hours old with nonenterotoxigenic strains of Escherichia coli. All developed clinical signs of watery mouth disease and seven died within 24 hours. The mean concentrations of several blood constituents were determined in samples taken at intervals until 24 hours after infection in infected lambs and in four control lambs. The biochemical and haematological changes observed in the lambs developing watery mouth disease were those characteristic of endotoxic shock.

Methodological problems in the use of participant observers.

A multiple baseline design across observed students and teachers was used to investigate the relationship between observations by participant observers and changes in the behavior of those observed ("observee" reactivity) and the observers (observer-mediator reactivity). Two teachers recorded consecutively the appropriate student verbalizations of four students and two teachers recorded the inappropriate student verbalizations of four students. Independent observers simultaneously recorded student verbalizations (appropriate and inappropriate) as well as teacher behaviors (positive, negative, and instruction) throughout all phases of the study. The results substantiated the prediction of "observee" reactivity and observer-mediator reactivity in one of four classrooms. The results of the present study suggest that in some instances, observations by participant observers may result in changes in the behavior of those being observed ("observee" reactivity) and/or the observers (observer-mediator reactivity).

The use of teachers as behavioral observers.

The effect of using teachers as behavioral observers on both student and teacher behavior was examined with eight teachers and 32 elementary school children. The frequency of prompts (but not praise or criticism) to those students observed by the teacher increased significantly from nonobserver to teacher observed experimental phases. In addition, students observed by the teacher showed more change in appropriate behavior than students who were not observed. The significance of these findings for research and therapy is discussed.

Accuracy of children on an open-loop pointing task.

The accuracy of active and passive movements was measured in 4-yr.- to 11-yr.-old children and in adults performing a visuo-manual pointing task without seeing their limbs. Accuracy varied according to age and nature of movement. The younger children performed accurate movements. At age 7 the accuracy suddenly decreased while the difference between active and passive movements increased. Between 7 and 11 yr., the active performance improved progressively until attaining an adult-like level, while the passive performance remained unchanged. It is concluded that a change occurs in the manner of controlling reaching movements at age 7.