Aconitine inhibits epileptiform activity in rat hippocampal slices

The effect of aconitine, an alkaloid neurotoxin known to bind at site 2 of the sodium channel, was investigated on epileptiform activity in hippocampal slices by use of extracellular recordings in CA1 pyramidal cell layer. Epileptiform activity was induced by bicuculline, picrotoxin, penicillin, pentylenetetrazol or by omission of magnesium from the bathing medium, respectively. In every case aconitine (0.1 and 1 microM) blocked the multiple population spikes representing the epileptiform activity. The onset of inhibition was shorter by use of an increased concentration of the epileptogenic drug. Epileptiform activity evoked by pentylenetetrazol and low magnesium was first increased by aconitine followed by a rapid inhibition, while the bicuculline-, picrotoxin-, and penicillin-induced epileptiform discharges were immediately abolished.

A rural nursing experience

This paper describes student observations and responses to an introduction of nursing in a rural area. As many rural areas of the United States continue to face a shortage of nurses, working in a rural area is an option for employment upon graduation. Independence is a major factor in choosing a rural setting for a nurse anesthesia practice.

A comparison of methods for measuring patient satisfaction with consultations in primary care

BACKGROUND

Attention needs to be paid to comparing and standardizing methods for measuring patient satisfaction with consultations in primary care.

OBJECTIVES

To compare the Medical Interview Satisfaction Scale (MISS) and the Consultation Satisfaction Questionnaire (CSQ) in terms of acceptability, distribution of responses, reliability and gather evidence of validity. In addition, to compare the scores of patients completing the questionnaires immediately after the consultation in the general practitioners' surgeries with those completing the questionnaires later at home.

METHODS

The two questionnaires were bound as a single instrument with order determined at random. This was given to patients immediately after their consultations in eight practices in South Glamorgan.

RESULTS

One hundred and ninety-eight of 316 (63%) patients completed and returned questionnaires. The distributions of patient satisfaction scores for the two questionnaires were very similar. For the MISS: mean 76.6% (SD 11.4); for the CSQ mean 7.2% (SD 12.6). Correlations between sub-scales ranged from 0.58-0.84 for the MISS and from 0.40-0.79 for the CSQ. The correlation between the overall scales was 0.82. Levels of reliability for the scales and sub-scales were fair to good ranging from 0.78-0.96 for the MISS and from 0.73-0.94 for the CSQ.

CONCLUSIONS

The study does not identify one scale as being superior in psychometric terms, however by demonstrating consistency of responses it provides support for the scales as measures of patient satisfaction for use in primary care. The level of inter-correlation suggests that the sub-scales may not be clearly independent of each other and suggests that total scores may be preferred. Lower levels of satisfaction are expressed if patients complete questionnaires at home rather than in general practitioners' surgeries.

(+/-)-kavain inhibits the veratridine- and KCl-induced increase in intracellular Ca2+ and glutamate-release of rat cerebrocortical synaptosomes

The action of (+/-)-kavain on the veratridine, monensin and KCl-depolarization evoked increase in free cytosolic Ca2+ concentration ([Ca2+]i), and its influence on the release of endogenous glutamate from rat cerebrocortical synaptosomes were investigated. [Ca2+]i was fluorimetrically determined employing FURA as the Ca2+ sensitive fluorophore, and glutamate was detected by a continuous enzyme-linked fluorimetric assay. The incubation of synaptosomes in the presence of (+/-)-kavain up to a concentration of 500 mumol/l affected neither basal [Ca2+]i nor spontaneous release of glutamate, but dose-dependently reduced both veratridine-elevated [Ca2+]i (IC50 = 63.2 mumol/l) and glutamate-release (IC500 = 116.4 mumol/l). The inhibition of these parameters, attained with 500 mumol/l(+/-)-kavain, could be overcome by inducing an artificial Na+ influx, using monensin as a Na+ ionophore, An application of (+/-)-kavain after veratridine caused a decrease in veratridine-elevated [Ca2+]i, which was similar to the action of tetrodotoxin (TTX) with regard to time course, half-life of [Ca2+]i decline and the final steady state level of [Ca2+]i. Concomitantly, veratridine-induced glutamate-release was blocked. The results indicate that specific inhibition of voltage-dependent Na+ channels is a primary target of (+/-)-kavain, thus preventing a [Na+]i provoked increase in [Ca2+]i and glutamate-release. However, pathways related to the elevation of [Ca2+]i by [Na+]i itself, and the processes involved in normalization of elevated [Ca2+]i and glutamate-release downstream to enhanced [Ca2+]i, seems to be unaffected by (+/-)-kavain. Using KCl-depolarized synaptosomes, 400 mumol/l (+/-)-kavain reduced, in analogy to Aga-GI toxin, KCl-evoked [Ca2+]i and diminished the part of glutamate-exocytosis which is related to external Ca2+ to about 75% of control. At a concentration of 150 mumol/l, which is above the IC50 value necessary to block voltage-dependent Na+ channels, (+/-)-kavain affected neither basal nor the KCl-induced increase in [Ca2+]i. These results might suggest that (+/-)-kavain at concentrations sufficient to block Na+ channels completely. moderately inhibits the non-inactivating Ca2+ channels located on mammalian presynaptic nerve endings.

Optimal display conditions for quantitative analysis of stereoscopic cerebral angiograms

For several years the authors have been using a stereoscopic display as a tool in the planning of stereotactic neurosurgical techniques. This PC-based workstation allows the surgeon to interact with and view vascular images in three dimensions, as well as to perform quantitative analysis of the three-dimensional (3-D) space. Some of the perceptual issues relevant to the presentation of medical images on this stereoscopic display were addressed in five experiments. The authors show that a number of parameters-namely the shape, color, and depth cue, associated with a cursor-as well as the image filtering and observer position, have a role in improving the observer's perception of a 3-D image and his ability to localize points within the stereoscopically presented 3-D image. However, an analysis of the results indicates that while varying these parameters can lead to an effect on the performance of individual observers, the effects are not consistent across observers, and the mean accuracy remains relatively constant under the different experimental conditions.

Subjective symptoms and quality of life in healthy subjects during a phase I study

OBJECTIVE

Participants in a phase I study were interviewed in order to establish the incidence and variability of subjective symptoms and changes in quality of life during phase I trials.

METHODS

The healthy subjects were randomized to receive a single dose of either 0.5 mg digoxin or an equivalent amount of each of four digitaloid mixtures every 14 days. The trial involved five 24-h monitoring periods. The duration of the study was 57 days. Wellbeing, subjective symptoms and quality of life were measured before, during and after the trial using the Freiburg Symptoms List (FSL), Wellbeing Scales (WBS), and Life Satisfaction Questionnaire (LSQ).

RESULTS

Eight healthy subjects (25 years) were enrolled in the study. Their subjective symptoms were below the reference values for healthy subjects for each test but above the theoretical minimum and maximum values for total wellbeing, indicating that healthy subjects-not just patients-display subjective symptoms and impairment of wellbeing to a greater or lesser extent prior to a clinical trial. In terms of the total study population, comparison of the questionnaire scores before, during and after the study disclosed no significant changes in wellbeing or quality of life. However, some participants displayed marked intraindividual fluctuation.

CONCLUSIONS

A careful exploration of the baseline symptoms is necessary even in healthy subjects to avoid observation bias. The symptom course differs greatly from individual to individual; therefore in a phase I study only group scores of wellbeing should be used to assess the possible effects of trial-related factors. A setting like the one used in our study does not impair the quality of life of healthy subjects and as such can be regarded as a fairly neutral means of measuring wellbeing.

Electrophysiological effects of aconitine in rat hippocampal slices

The electrophysiological effects of aconitine were investigated in the rat hippocampal slice and compared with those of veratridine. Both alkaloids are known to bind at site 2 of sodium channels and to block its inactivation. Extracellular recordings revealed that aconitine and veratridine exert inhibitory effects on neuronal excitability. Aconitine slowly and reversibly decreased the population spike recorded in the CA1 pyramidal cell layer. The reduction of the spike amplitude was similar whether orthodromically or antidromically activated. The aconitine-induced inhibition did not differ from that of veratridine. However, following washout of aconitine, the amplitude of the antidromic spike was increased compared to the control amplitude. The veratridine-induced inhibition was only partially reversible. This inhibition was also observed during suppression of synaptic transmission by a low Ca2+/high Mg2+-medium, indicating an inhibition of axonal conductance. The results show that in the absence of synaptic transmission the antidromic (alvear) spike is more sensitive to the inhibitory action of aconitine than the presynaptic fiber spike elicited by stimulation of the Schaffer collaterals. Furthermore, it is shown that aconitine acts in an activity-dependent manner, in that the latency of onset of the inhibition is prolonged when the stimulation frequency is decreased. Field excitatory postsynaptic potentials were also suppressed by aconitine, whereas excitatory postsynaptic currents recorded by the patch clamp technique were not influenced by aconitine when cells were held at -60 mV.

Three-dimensional multimodal image-guidance for neurosurgery

The authors address the use of multimodality imaging as an aid to the planning and guidance of neurosurgical procedures, and discuss the integration of anatomical (CT and MRI), vascular (DSA), and functional (PET) data for presentation to the surgeon during surgery. The authors' workstation is an enhancement of a commercially available system, and in addition to the guidance offered via a hand-held probe, it incorporates the use of multimodality imaging and adds enhanced realism to the surgeon through the use of a stereoscopic three-dimensional (3-D) image display. The probe may be visualized stereoscopically in single or multimodality images. The integration of multimodality data in this manner provides the surgeon with a complete overview of brain structures on which he is performing surgery, or through which he is passing probes or cannulas, enabling him to avoid critical vessels and/or structures of functional significance.

Four mutations in the porphobilinogen deaminase gene in patients with acute intermittent porphyria

We have detected four different mutations in the porphobilinogen deaminase (PBGD) gene in acute intermittent porphyria (AIP) families from England, Norway, and Sweden. A splicing mutation in the first position of intron 8 (Int8 + 1) was found in a family from England and a missense mutation in exon 12 (Glu250) was detected in a Norwegian family. Two mutations were identified in Swedish families, one splicing mutation in the first position of intron 3 (Int3 + 1) and one missense mutation in exon 8 (Pro119).

In vitro activities of the lichen secondary metabolites vulpinic acid, (+)-usnic acid, and (-)-usnic acid against aerobic and anaerobic microorganisms

Secondary metabolites of different species of lichen were tested for their activities against a variety of microbial species. While gram-negative rods and fungi were not inhibited by these compounds, Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, and some anaerobic species (Bacteroides and Clostridium species) were susceptible at the concentrations tested. Vulpinic acid generally was less active than usnic acid, regardless of its stereochemistry. The susceptibility to usnic acid was not impaired in clinical isolates of S. aureus resistant to methicillin and/or mupirocin.

No association between the c2 allele at the cytochrome P450IIE1 gene and alcohol induced liver disease, alcohol Korsakoff's syndrome or alcohol dependence syndrome

Cytochrome P450IIE1 metabolises, and is induced by ethanol. The 5' regulatory sequence of the gene is polymorphic; that identified by the c2 allele has been shown by transfection studies to confer an increased rate of transcription. A recent report indicating an association between this allele and alcohol induced cirrhosis suggests that it may contribute to the genetic vulnerability to this disease. We have examined this polymorphism in patients of western European origin with alcohol induced cirrhosis, alcohol Korsakoff's syndrome and alcohol dependence syndrome. We were unable to detect any association between this allele and any of these diseases.

(+/-)-Kavain inhibits veratridine-activated voltage-dependent Na(+)-channels in synaptosomes prepared from rat cerebral cortex

Kava pyrones are pharmacologically active compounds extracted from Piper methysticum Forst. Because kava pyrones were characterized by their anticonvulsive, analgesic and centrally muscle relaxing action, we investigated the influence of (+/-)-kavain, a synthetic kava pyrone, on veratridine-stimulated increase in intrasynaptosomal Na+ concentration ([Na+]i) of rat cerebrocortical synaptosomes. [Na+]i was measured spectrofluorometrically employing SBFI as Na+ sensitive fluorescence dye. Veratridine (5 mumol/I) enhanced basal [Na+]i 6.6-fold from 11.3 to 74.1 mmol/l Na+. Incubation of synaptosomes for 100 sec with (+/-)-kavain was sufficient to reduce dose dependently the stimulated increase of [Na+]i with an IC50 value of 86.0 mumol/l, and almost complete inhibition of Na(+)-channels was attained with 400 mumol/l) reduced veratridine-elevated [Na+]i to 30.4% and 7.9% of control whereas the centrally acting muscle relaxant mephenesin (400 mumol/l) was without any effect. Postapplication of 400 mumol/l (+/-)-kavain or 10 mumol/l TTX immediately diminished veratridine-elevated [Na+]i to nearly basal levels with a half life time of 69.7 and 41.8 sec, respectively. To study the influence of (+/-)-kavain on non stimulated synaptosomes, an increase in [Na+]i was induced by 200 mumol/l ouabain, which enhanced [Na+]i hyperbolically with an initial rate of 18.4 mmol Na+/l min. Preincubation of synaptosomes with 400 mumol/l (+/-)-kavain or 10 mumol/l TTX partly prevented Na(+)-influx for both compounds to the same extent of about 57% of control. The presented data indicate a fast and specific inhibition of voltage-dependent Na(+)-channels by (+/-)-kavain.

Compensation of multi-dimensional selective excitation pulses using measured k-space trajectories

Multidimensional spatially selective excitation pulses rely on the accuracy of gradient waveforms to achieve desired excitation volumes. Unfortunately, the high gradient slew-rates and magnitudes required by these pulses often lead to distortion of the waveforms produced by imaging systems resulting in poor selection profiles. In this paper, a k-space calibration procedure, used to determine the actual trajectory produced by the scanner's field gradients, is extended to two spatial dimensions. This measured information is then incorporated in a selective excitation design technique for correcting the RF pulse envelopes to compensate for gradient waveform induced distortion of the excitation volumes.

"Playing God" and germline intervention

The phrase "playing God" so popular with journalists takes on a serious meaning in the debate over germline genetic intervention. While guarding against the dangers of human pride implied in the phrase "playing God," special attention is given here to the Christian concept of the human being as created in the divine image, the imago dei. Human beings are dubbed "created co-creators." In this light ethical arguments proscribing germline intervention are examined and refuted, leaving the door open for creative responsibility on the part of the present generation for our future progeny.

Hepatitis B virus infection without immunological markers after open-heart surgery

Post-transfusion hepatitis is still an important problem, despite the screening of blood donors for hepatitis B (HBV) and C virus infections. We assessed whether HBV DNA might be detected by PCR in prospectively collected serum samples of patients with unexplained post-transfusion hepatitis but no immunological HBV markers. We found HBV DNA in 4 (20%) of 20 patients with unexplained post-transfusion hepatitis and in 5 patients with mildly increased aminotransferases. The clinical course of these HBV infections was usually mild and self-limiting. Thus we found that low-titre, immunologically negative HBV infections do exist and might represent a significant cause of post-transfusion hepatitis.

Differential effect of R 56865 on ouabain binding to isolated sarcolemma and intact atrial tissue of guinea-pig

1. R 56865 (N-[1-[4-(4-fluorophenoxy)-butyl]-4-piperidinyl]-N-methyl- 2-benzothiazolamine) is a compound known to antagonize cardiac glycoside intoxication. Therefore, the effect of the compound on ouabain binding to intact cardiac tissue as well as cardiac membrane preparations was investigated. 2. The binding of ouabain to highly purified sarcolemmal membranes was not influenced by R 56865 1 x 10(-6) mol l-1 (ouabain: KD = 1.3 x 10(-7) mol l-1, Bmax = 160 pmol mg-1; ouabain + R 56865: KD = 1.4 x 10(-7) mol l-1, Bmax = 168 pmol mg-1). 3. In contrast to the results in purified membranes, the binding of ouabain (10(-8) mol l-1 to 5 x 10(-7) mol l-1) to intact atria was significantly reduced. 4. Ouabain, 5 x 10(-7) mol l-1, led to a transient positive inotropic effect of about 220% followed by a developing negative inotropic effect after 3 h. R 56865, 10(-7) mol l-1, led to a maximal positive inotropic effect of about 290% also followed by a delayed decline of contractile force. A tenfold higher concentration of R 56865 led to sustained positive inotropic effect of about 250% in the same time interval. 5. The different effects of R 56865 on ouabain binding in subcellular preparations and intact tissue do not support the view that R 56865 interferes directly with the action of ouabain on Na/K-ATPase. An indirect effect, which may be mediated by a lowered intracellular sodium load is discussed.

Curvilinear reconstruction of 3D magnetic resonance imaging in patients with partial epilepsy: a pilot study

In an attempt to better delineate the abnormalities associated with focal cortical dysgenesis, we performed curvilinear reformatting of the cortex from 3D magnetic resonance (MR) images. Illustrative patients with partial seizures and conventional orthogonal MRI evaluation show that small regions of cortical thickening suggestive of focal dysplastic lesions may not be recognized. In three such patients the curvilinear reformatting demonstrated two additional focal abnormalities of the cortical gyri and better defined the two focal lesions found on conventional orthogonal MR images. This method promises to be a useful tool in the evaluation of epileptic patients with proven or suspected subtle structure cortical abnormalities, particularly focal neuronal migration disorders where cortical thickening, abnormal gyral pattern, and poor delineation of the gray-white matter transition are the main findings.

Measuring functional health status in primary care using the COOP-WONCA charts: acceptability, range of scores, construct validity, reliability and sensitivity to change

BACKGROUND

The COOP-WONCA charts comprise six scales designed to measure functional health status in primary care.

AIM

A study was undertaken to describe the acceptability, distribution of chart scores, construct validity, test-retest reliability and sensitivity to change when these charts were used in the United Kingdom.

METHOD

For acceptability, distribution of scores and construct validity, data were obtained from 100 consecutive consulting patients aged 16 years and over and 100 non-consulting age-sex matched individuals from one general practice. In order to examine reliability and sensitivity to change, both groups were followed up two weeks later.

RESULTS

Regarding acceptability, four patients refused to complete the charts during the initial recruitment of the consulters; 74 out of 100 non-consulters returned the first postal questionnaire. The follow-up questionnaire was returned by 68 out of 100 consulters and 57 out of 74 non-consulters. Overall distributions of scores demonstrated reasonable variation. Regarding construct validity, differences between the consulters and non-consulters were all in the anticipated direction and reached statistical significance for three of the six charts. For reliability, the proportion of non-consulters whose scores were unchanged ranged from 56% to 73%. For those whose scores changed, the differences were small and evenly balanced. For sensitivity to change, the proportion of consulters whose scores altered ranged from 45% to 59% with mean changes all indicating improvements in health. There were larger changes for patients consulting about acute problems than for those with chronic problems.

CONCLUSION

It appears that the charts were acceptable, with reasonable distributions of scores and evidence of construct validity. Moderate levels of reliability and sensitivity to change were demonstrated. This study suggests that the COOP-WONCA charts are suitable for measuring functional health status in primary care in the UK.

Frameless stereotaxy for surgery of the epilepsies: preliminary experience. Technical note

Frameless stereotactic techniques used in conjunction with three-dimensional images allow accurate planning and performance of a variety of neurosurgical procedures. The authors have used the frameless stereotactic Allegro Viewing Wand system to provide real-time correlation of the operating field and computerized images in 42 neurosurgical operations, including 31 epilepsy procedures. The system consists of an image-processing computer that creates three-dimensional and triplanar images; a mobile computer to display reformatted magnetic resonance images; and a hand-guided, articulated, position-sensing arm with a probe. At the start of the operation, the probe identifies the patient's facial and scalp features and correlates these with the computerized images. The position-sensing arm can then guide the operation and locate anatomical structures and lesions of interest. This system can be used to advantage in performing smaller craniotomies and intraoperatively locating anatomical structures and lesions to be removed. Postoperative magnetic resonance images demonstrate that this technique was accurate to within 3 mm in measuring the anteroposterior resection of fixed structures, such as hippocampus and corpus callosum. Disadvantages include longer preoperative preparation for data analysis and lack of both real-time computer analysis of tissue removal and angiographic data display. Preliminary experience suggests that the viewing wand system's advantages outweigh the disadvantages, and it is most helpful as an adjunctive navigational device in the microsurgical treatment of epilepsy.