Rapid isolation of some antiepileptic hydantoins and their analogues with Sep-Pak C18 cartridges and capillary gas chromatography with splitless injection

Summary A simple and rapid method for isolation of seven antiepileptics (2 hydantoin, 2 oxazolidin, and 3 suximide derivatives) from urine and plasma is presented. Urine and plasma (1 ml) samples containing seven antiepileptics were mixed with distilled water (4 ml), and the sample solution was poured into a pretreated Sep-Pak C₁₈ cartridge; this was washed with water and chloroform/methanol was passed through it to elute the antiepileptics. The eluate was mixed with isoamyl acetate and evaporated under a stream of N₂. The drugs were detected by gas chromatography with fused silica capillary columns, splitless injection and flame ionization detection. Separation of the seven antiepileptics from each other and from impurities was satisfactory with the use of an SPB-1 capillary column. The detection limit for the seven antiepileptics with the present method was 0.1–1.0 g/ml urine or plasma. The recovery of the drugs from urine and plasma was more than 70% and 50%, respectively. Offprint requests to: O. Suzuki     

Selective attenuation of neuropeptide-Y-mediated contractile responses in blood vessels from patients with diabetes mellitus

Vascular smooth muscle contractile responses to neuropeptide Y, ,ß-methyleneATP and noradrenaline were studied in circular segments of isolated vessels with intact endotheliumin vitro from 12 patients with diabetes mellitus type 2 (NIDDM) and 12 control subjects. The dilatory effect of acetylcholine was used to test the function of the endothelium. Subcutaneous arteries and veins (diameter 0.1–1.1 mm) were obtained during surgery. There was no difference in contractile responses to noradrenaline or ,ß-methyleneATP between diabetic and control vessels. The contractile response to neuropeptide Y, however, was markedly reduced in the diabetic group. The maximal contractile effect (46.0 ± 14.0%,p < 0.05) but not the sensitivity to neuropeptide Y was significantly less in diabetic veins compared to control (107.5 ± 19.6%). Thus, the attenuation of neuropeptide Y responses was present in humans as previously observed in alloxan-induced diabetes mellitus in rabbits. There was no difference in the dilator effect of acetylcholine between the diabetic and the control group in any of the vessel types, indicating that the difference in vascular reactivity to neuropeptide Y was not endothelium-dependent. In conclusion, the present study has shown that the postjunctional effects of neuropeptide Y, a co-transmitter of the peripheral sympathetic nervous system, is selectively attenuated in diabetes mellitus.     

Non-invasive assessment of skeletal kinetics using fluorine-18 fluoride positron emission tomography: evaluation of image and population-derived arterial input functions

To measure regional skeletal kinetics using fluorine-18 fluoride positron emission tomography (PET) it is necessary to know the concentration of radioactive tracer being delivered to bone by arterial plasma with relation to time, the arterial input function (IFa). Methods by which IFa can be derived without arterial sampling are attractive because of their relative technical simplicity and the reduction in possible morbidity to the subject. We have compared the use of a scaled population input function (IFp) and a corrected image-derived input function from the aorta (IFi) with an IFa directly measured from a radial artery line in ten normal postmenopausal women. Both of the aforementioned methods rely only on a small number of discrete venous samples. Each subject had a dynamic PET acquisition of the lumbar spine performed after the intravenous injection of 180 MBq ¹⁸F-fluoride. Both the IFp and the IFi were compared with the IFa in terms of the accuracy of determination of six parameters. These were: plasma clearance of fluoride to bone mineral (K _i), unidirectional plasma clearance to total bone tissue (K ₁) and individual rate constants k ₂, k ₃ and k ₄, calculated using non-linear regression with a three-compartment model, and the plasma clearance to bone mineral calculated using the Patlak method (K _pat). For both the IFp and the IFi method the root mean square errors for K _pat and K _i were similar and small (<8.2%). The errors in determining K ₁ and the rate constants k ₂ to k ₄ are larger by either method, but with a small advantage using the IFp method. It is concluded that the use of either non-invasive method for determining the arterial plasma input function is suitable for the measurement of the most important parameters, K _i and K _pat, in these subjects. Received 8 April and in revised form 11 July 1999     

Decreased β2-adrenoceptor density and decreased isoproterenol induced c-AMP increase in juvenile type I diabetes mellitus: An additional cause of severe hypoglycaemia in childhood diabetes?

Little is known about the receptor and post receptor mechanisms of sympathoadrenal signal transmission in type I diabetes mellitus. Therefore, we examined the maximum binding of granulocyte ₂-adrenoceptors and the in vitro c-AMP accumulation in lymphocytes of 24 children and adolescents with diabetes mellitus and 14 similarly aged healthy subjects. The number of high affinity ₂-adrenoceptors on granulocytes correlated significantly with unstimulated (r=0.6,P<0.004) and with isoproterenol stimulated c-AMP values in lymphocytes (r=0.68,P<0.0007) showing the proportional changes of ₂-adrenoceptors and c-AMP in two different cells. The number of ₂-adrenoceptors on granulocytes was significantly reduced in diabetic as compared to healthy children (median 1397, range 599–3405 vs. 2205, 825–3200 ₂-adrenoceptors per granulocyte,P=0.014). Moreover, the percentage in vitro stimulation of c-AMP by isoproterenol in lymphocytes was significantly reduced in diabetic children as compared to healthy individuals (120%, 39%–278% vs. 225%, 66%–500%,P=0.012). These results indicate a decreased sympathoadrenergic signal transmission in peripheral blood cells as a model for the liver probably contributing to severe hypoglycaemia in diabetic children.     

The sunflower syndrome. A new look at "self-induced" photosensitive epilepsy

The stereotyped, episodic abnormal behaviour manifested by a child and her mother on exposure to a particular sort of sunlight is described in detail. The child is the first fully documented patient with this so-called "self-induced" form of photosensitive epilepsy in whom for several years no electroencephalographic sensitivity to flickering light could be demonstrated. The probability that the cingulate circuit may be the anatomical substrate involved in the pathogenesis of these patients' unusual response to sunlight is discussed. Both patients also exhibited remarkably persistent habit rhythmias--the one common to both being that of circling.     

A comparison of digital subtraction angiography and noninvasive testing in the diagnosis of cerebrovascular disease

Among the 1,892 patients who underwent cerebrovascular digital subtraction angiography at our hospital over the past 18 months, there was a subgroup of 34 patients (65 carotid arteries) for whom noninvasive cerebrovascular test results and standard cerebral arteriograms were also available. These patients were reviewed retrospectively and the ability of both methods to detect hemodynamically significant lesions, defined as a greater than 50 percent reduction in the diameter of the carotid artery, was determined using the arteriograms as the "gold standard." Noninvasive cerebrovascular tests had a sensitivity of 81 percent, a specificity of 95 percent, a positive predictive value of 92 percent, a negative prediction value of 88 percent, and an overall accuracy of 89 percent. Digital subtraction angiography had a sensitivity of 84 percent, a specificity of 92 percent, a positive predictive value of 88 percent, a negative predictive value of 89 percent, and an overall accuracy of 89 percent. If the four cases of hemodynamically significant stenosis of the carotid siphon not detected by digital subtraction angiography had been considered as false-negatives, its sensitivity would have been reduced to 72 percent. In patients with hemispheric cerebral ischemia, we found noninvasive cerebrovascular tests neither necessary nor cost-effective. Digital subtraction angiography, on the other hand, often provided definitive diagnostic information in such patients if the intracranial circulation was well defined and the extracranial lesion corresponded to the patients' symptoms. Noninvasive cerebrovascular testing was the safest and most cost-effective technique for screening patients with asymptomatic bruits, atypical, nonhemispheric cerebral symptoms, and those who have undergone carotid endarterectomy. If the noninvasive cerebrovascular test result was positive or equivocal, digital subtraction angiography was performed to localize the responsible lesion and exclude carotid occlusion.     

Widespread Horizontal Connections Arising from Layer 5/6 Border Inverted Cells in Rabbit Visual Cortex

Herein we describe the inverted cells [defined as those projection neurons having a major dendritic shaft abpially oriented (Bueno-López et al., Eur. J. Neurosci. , 3, 415, 1991)] originating a unique set of cortical connections characterized by extraordinarily widespread horizontal distribution. Single and multiple injections of wheatgerm agglutinin - horseradish peroxidase were made in areas 17 and 18 and the resulting retrograde labelling in the cortex was analysed. The findings were assessed in independent control experiments in which Fluoro-Gold was used as retrograde tracer. Following single injections in area 17 several separate patches of labelled cells comprising layers 2–6 were consistently found in area 18. In addition to these associational cells a number of labelled cells appeared at the layer 5/6 border but were distributed over most of the tangential extent of the visual occipital cortex. This widespread pattern was particularly striking in brains after multiple injections. In these brains a conspicuous band of labelled cells at the 5/6 border radiated from the injection sites, making up an apparently continuous horizontal sheet that intersected the striate - extrastriate boundary and merged with the patches of labelled cells in area 18 and beyond. Most of the cells in the 5/6 border band were inverted cells (82%; n = 2081). Injections in area 18 failed to produce such a widespread set of labelled cells in area 17. The functional significance of these connections furnished by the 5/6 border inverted cells remains to be determined, but their distribution would allow for convergent/divergent binding interactions both intra-areally (within area 17) and inter-areally (from area 18 to area 17).     

Comparative patterns of i-antigen expression, F-cell frequency and Hb A2 level in acute myeloid leukemia and in acute lymphoid leukemia

Hb F, Hb A₂ and i-antigen expression were investigated in adulthood acute leukemias. The study of i-antigen expression by immuno-agglutination and immunofluorescence showed that it is preferentially increased among AML patients. A similar result was obtained for F-cell frequency which was often increased in AML, while it was normal in ALL. Hb A₂ level was significantly lower in AML than in ALL. These differences between AML and ALL red cell patterns further suggest that the leukemic clone involves the erythroid lineage in AML but not in ALL.     

The "throbbing sign"--an indication of early venous congestion in replantation surgery.

Venous congestion in a replanted or transplanted digit can be detected, even before any obvious color changes, by the "throbbing" elicited by pinching the digit between the thumb and finger of the examiner until the skin blanches. Releasing the pressure slowly, a sensation of throbbing will be felt synchronous with the patient's pulse rate. The sign disappears when venous congestion is relieved or when swelling persists and increases enough to lessen the arterial inflow.     

Aktivierungsverhalten bei sensumotorischer regeltätigkeit in abhängigkeit von der leistung

Zusammenfassung Mit 40 Versuchspersonen wurde Kompensationstracking durchgeführt. Anhand des Leistungsparameters Regelfehler wurden 2 Gruppen gebildet, bei denen untersucht wurde, ob sie sich im Aktivierungsverhalten unterscheiden. Es wurde gefunden, daß die Herzfrequenz- und Atemfrequenzsteigerungen in allen Versuchsabschnitten bei der Gruppe mit guter Trackingleistung signifikant höher waren. Die Streuung der Herzfrequenz war bei der schlechten Gruppe geringer.Die Aktivierungsvariablen Herz- und Atemfrequenz unterscheiden sich am deutlichsten in der jeweils ersten Belastungsminute der Versuchsabschnitte, dabei spiegelt die Herzfrequenz die Aufgabenschwierigkeit besser wider als die Atemfrequenz.Die Untersuchung der Korrelation zwischen dem Leistungsparameter Regelfehler und Herzfrequenzanstieg ergibt bei der Gruppe mit schlechterer Trackingleistung immer negative Werte für r, die in 3 Belastungsabschnitten signifikant sind. Bei der Gruppe mit guter Trackingleistung besteht eine positive Korrelation zwischen Herzfrequenzanstieg und Regelfehler bei geringerer statistischer Sicherheit.Die Ergebnisse werden diskutiert und Schlußfolgerungen für die psychophysiologische Eignungsbeurteilung werden abgeleitet.