Retention rate of zonisamide in intractable epilepsy.

OBJECTIVES: To assess the effect and tolerability of zonisamide (ZNS) as adjunctive treatment for difficult-to-treat epilepsy in adult Scandinavian patients. MATERIAL AND METHODS: 151 outpatients (mean age: 42.5 years) from 18 centres in Denmark, Sweden and Norway were recruited to the study. 81.5% had focal epilepsy, and the mean number of previously tried AEDs was 4.5. The patients were given ZNS as add-on treatment, and the ZNS dosing and the visit frequency were governed by the treating physician. The primary efficacy endpoint was the retention rate after 12-month treatment. Assessments included also responder rate, type and frequency of adverse events, healthcare resource utilization (HCRU) and quality of life (QOLIE-31). RESULTS: 90 patients (59.6%) completed the study. Mean daily ZNS dose was 300.8 mg. After 12 months, 81 patients were still on ZNS, that is a retention rate of 53.6%. The mean reduction of seizure frequency at 12 months was 27%. Best effect was seen in those with focal and those with secondary generalized seizures. In the QOLIE-31, there was a mean increase from baseline of 4.8 points. The tolerability was generally good. The majority of side effects were CNS-related, dizziness, fatigue, seizure aggravation, and headache being most prevalent. 21.2% had adverse events leading to withdrawal of ZNS. CONCLUSIONS: A retention rate of 53.6% after 1 year of treatment with ZNS is roughly in accordance with the retention rates found for lamotrigine, oxcarbazepine, levetiracetam and topiramate in drug-resistant patients.

Assessing surgical quality: comparison of general and procedure-specific morbidity estimation models for the risk adjustment of pancreaticoduodenectomy outcomes.

INTRODUCTION: The use of outcomes to evaluate surgical quality implies the need for detailed risk adjustment. The physiological and operative severity score for the enumeration of mortality and morbidity (POSSUM) is a generally applicable risk adjustment model suitable for pancreatic surgery. A pancreaticoduodenectomy (PD)-specific intraoperative pancreatic risk assessment (IPRA) estimates the risk of postoperative pancreatic fistula (POPF) and associated morbidity based on factors that are not incorporated into POSSUM. OBJECTIVE: The aim of the study was to compare the risk estimations of POSSUM and IPRA in patients undergoing PD. METHODS: An observational single-center cohort study was conducted including 195 patients undergoing PD in 2008-2010. POSSUM and IPRA data were recorded prospectively. Incidence and severity of postoperative morbidity was recorded according to established definitions. The cohort was grouped by POSSUM and IPRA risk groups. The estimated and observed outcomes and morbidity profiles of POSSUM and IPRA were scrutinized. RESULTS: POSSUM-estimated risk (62 %) corresponded with observed total morbidity (65 %). Severe morbidity was 17 % and in-hospital-mortality 3.1 %. Individual and grouped POSSUM risk estimates did not reveal associations with incidence (p = 0.637) or severity (p = 0.321) of total morbidity or POPF. The IPRA model identified patients with high POPF risk (p < 0.001), but was even associated with incidence (p < 0.001) and severity (p < 0.001) of total morbidity. CONCLUSION: The risk factors defined by a PD-specific model were significantly stronger predictive indicators for the incidence and severity of postoperative morbidity than the factors incorporated in POSSUM. If available, reliable procedure-specific risk factors should be utilized in the risk adjustment of surgical outcomes. For pancreatic surgery, generally applicable tools such as POSSUM still have to prove their relevance.

Auroral-particle precipitation and trapping caused by electrostatic double layers in the ionosphere.

Interpretation of high-resolution angular distribution measurements of the primary auroral electron flux detected by a rocket probe launched into a visible aurora from Fort Churchill in the fall of 1966 leads to the following conclusions. The auroral electron flux is nearly monoenergetic and has a quasi-trapped as well as a precipitating component. The quasi-trapped flux appears to be limited to a region defined by magnetic-mirror points and multiple electrostatic double layers in the ionosphere. The electrostatic field of the double-layer distribution enhances the aurora by lowering the magnetic-mirror points and supplying energy to the primary auroral electrons.

Fragmentation of nitrogen-14 nuclei at 2.1 gev per nucleon.

An experiment has been carried out at the bevatron on the nuclear fragmentation of nitrogen-14 ions at an energy of 2.1 billion electron volts (Gev) per nucleon. Because of the near equality of the velocities of the nitrogen-14 beam and the fragmentation products at an angle of 0 degrees , we find it possible to identify the nuclear fragments isotopically.

PKC-dependent stimulation of exocytosis by sulfonylureas in pancreatic beta cells.

Hypoglycemic sulfonylureas represent a group of clinically useful antidiabetic compounds that stimulate insulin secretion from pancreatic beta cells. The molecular mechanisms involved are not fully understood but are believed to involve inhibition of potassium channels sensitive to adenosine triphosphate (KATP channels) in the beta cell membrane, causing membrane depolarization, calcium influx, and activation of the secretory machinery. In addition to these effects, sulfonylureas also promoted exocytosis by direct interaction with the secretory machinery not involving closure of the plasma membrane KATP channels. This effect was dependent on protein kinase C (PKC) and was observed at therapeutic concentrations of sulfonylureas, which suggests that it contributes to their hypoglycemic action in diabetics.

Male-to-female transsexuals show sex-atypical hypothalamus activation when smelling odorous steroids.

One working hypothesis behind transsexuality is that the normal sex differentiation of certain hypothalamic networks is altered. We tested this hypothesis by investigating the pattern of cerebral activation in 12 nonhomosexual male-to-female transsexuals (MFTRs) when smelling 4,16-androstadien-3-one (AND) and estra-1,3,5(10),16-tetraen-3-ol (EST). These steroids are reported to activate the hypothalamic networks in a sex-differentiated way. Like in female controls the hypothalamus in MFTRs activated with AND, whereas smelling of EST engaged the amygdala and piriform cortex. Male controls, on the other hand, activated the hypothalamus with EST. However, when restricting the volume of interest to the hypothalamus activation was detected in MFTR also with EST, and explorative conjunctional analysis revealed that MFTR shared a hypothalamic cluster with women when smelling AND, and with men when smelling EST. Because the EST effect was limited, MFTR differed significantly only from male controls, and only for EST-AIR and EST-AND. These data suggest a pattern of activation away from the biological sex, occupying an intermediate position with predominantly female-like features. Because our MFTRs were nonhomosexual, the results are unlikely to be an effect of sexual practice. Instead, the data implicate that transsexuality may be associated with sex-atypical physiological responses in specific hypothalamic circuits, possibly as a consequence of a variant neuronal differentiation.

Aromatic-L-amino-acid decarboxylase activity in mouse pancreatic islets.

Aromatic-L-amino-acid decarboxylase activity has been measured in intact or homogenised pancreatic islets of ob/ob mice (Umeå ob/ob). The method used involves the trapping and measuring of the 14CO2 released from L-[1-14C]dihydroxyphenylalanine (L-dopa). Islets showed a decarboxylase activity which was dependent on pyridoxal phosphate and inhibitable by 0.1 mM benserazide or 0.1 mM alpha-monofluoromethyldopa. Maximum activity in intact islets was about 330 mmol/kg dry islet per h with an apparent Km of 3.3 mM. Islet homogenates had a Vmax of about 120 mmol/kg per h with a Km of 0.3 mM. L-5-Hydroxytryptophan, m-tyrosine and o-tyrosine interfered with the decarboxylation of L-dopa in a way that suggested a high activity also towards those substrates. L-Phenylalanine, L-tyrosine and D-glucose had no effect. At 0.05 mM L-dopa islet homogenates showed a much higher activity than homogenates of liver, kidney, or spleen. Islet uptake of L-[3H]dopa was well in excess of the decarboxylation rate and thus probably not rate-limiting. It is concluded that mouse pancreatic islets have a high activity of aromatic-L-amino-acid decarboxylase. This is in accordance with previous suggestions of a stimulatory effect of this enzyme on insulin secretion.

5-hydroxytryptamine stimulates 86Rb+ efflux from pancreatic beta-cells.

The effects of 5-hydroxytryptamine and 5-hydroxytryptophan on 86Rb+ efflux from prelabelled ob/ob-mouse islets were studied to better understand the cellular mechanisms underlying the effects of 5-hydroxytryptamine and 5-hydroxytryptophan on insulin release. 5-Hydroxytryptophan (4 mM) had no effect on 86Rb+ efflux either at a low (3mM) or at a high (20 mM) D-glucose concentration, whereas 5-hydroxytryptamine (4 mM) stimulated 86Rb+ efflux at both glucose concentrations. These results indicate that 5-hydroxytryptamine may reduce glucose-induced insulin release by inhibiting early steps in the beta-cell stimulus-secretion coupling.

Coronary nitric oxide production in response to exercise and endothelium-dependent agonists.

BACKGROUND: Endothelium-derived nitric oxide (NO) contributes to epicardial coronary artery vasodilation during exercise. However, blockade of NO production does not impair the increase in coronary blood flow (CBF) during exercise, suggesting that NO is not obligatory for exercise-induced coronary resistance vessel dilation. In contrast, the increases in CBF produced by endothelium-dependent agonists are decreased after NO blockade. Consequently, this study was performed to determine whether the increase in coronary NO production in response to agonists is greater than that which occurs during exercise. METHODS AND RESULTS: We measured the oxidation products of NO (nitrate+nitrite=NO(x)) in aortic and coronary sinus plasma using chemiluminescence to assess NO(x) production across the coronary circulation in chronically instrumented dogs during a 3-stage treadmill exercise protocol and in response to intracoronary administration of the endothelium-dependent agonists acetylcholine (37.5 microg/min) and bradykinin (3.0 microg/min). No coronary NO(x) production could be detected at rest or during the first 2 stages of exercise; only at the highest level of exercise was a small increase in coronary NO(x) production measured. In contrast, coronary production of NO(x) was significantly increased in response to endothelium-dependent agonists. CONCLUSIONS: Coronary NO production in response to endothelium-dependent agonists is greater than in response to the increase in shear stress associated with exercise. These findings support previous studies suggesting that NO is not required for the coronary vasodilation that occurs in the normal heart during exercise.

Endogenous adenosine and coronary vasoconstriction in hypoperfused myocardium during exercise.

OBJECTIVE: The coronary circulation has been shown to remain responsive to vasodilator and vasoconstrictor stimuli during myocardial ischaemia. The aim of this study was to investigate whether endogenous adenosine attenuates coronary vasoconstriction caused by the thromboxane A2 analogue, U46619. METHODS: Nine chronically instrumented dogs were studied during treadmill exercise in the presence of a coronary stenosis which resulted in distal left circumflex coronary artery hypoperfusion. Myocardial blood flow was assessed with radioactive microspheres during exercise prior to and during intracoronary infusion of U46619 (0.01 microgram.kg-1 x min-1), in the absence and the presence of adenosine receptor blockade with intravenous 8-phenyltheophylline (5 mg.kg-1) and intracoronary adenosine deaminase (50 units.kg-1). Distal coronary pressure was maintained constant during the control stenosis and the three interventions, at 49(SEM 3), 50(3), 50(3), and 50(3) mm Hg. RESULTS: During control exercise mean myocardial blood flow was 0.91(0.09) ml.min-1 x g-1 in the stenosis region and 2.54(0.28) in the normal region. With no change in distal coronary pressure, U46619 decreased mean myocardial blood flow to 0.70(0.10) ml.min-1 x g-1 (p < 0.05). Adenosine blockade alone decreased myocardial blood flow in the stenosis region to 0.60(0.07) ml.min-1 x g-1 (p < 0.05 v control stenosis), indicating that endogenous adenosine contributed to coronary vasodilatation in the ischaemic region. However, adenosine blockade did not augment the vasoconstriction in response to U46619 [mean myocardial blood flow 0.49(0.05) ml.min-1 x g-1], indicating that endogenous adenosine did not attenuate the vasoconstriction caused by U46619. CONCLUSIONS: Endogenous adenosine contributed to dilatation of resistance vessels in hypoperfused myocardium of exercising dogs in the absence as well as in the presence of U46619. However, endogenous adenosine did not attenuate the magnitude of the vasoconstrictor response to U46619. These findings are best explained by observations that thromboxane A2 and adenosine act on coronary vascular segments of different size.

The correlation between calcium outflow and growth hormone release in perifused rat somatotrophs.

The time-relationships between GH secretion and 45Ca2+ efflux in response to human GRF (hGRF)-(1-29), hGRF-(1-44), 3-isobutyl-1-methylxanthine (IBMX), (Bu)2-cAMP, and high extracellular K+ were studied in perifused cultured rat somatotrophs. In cells exposed to 1-10 nM hGRF-(1-29) or -(1-44), GH release and 45Ca2+ efflux increased during the first 15 sec and reached peak values within 75 sec. At lower GRF concentrations, 45Ca2+ efflux still increased within 15 sec while GH secretion commenced 15-30 sec later. hGRF-(1-29) increased GH release and 45Ca2+ efflux also after 30 min preperifusion in a calcium-depleted medium with 0.1 mM EGTA added during the last 5 min of preperifusion. However, the magnitude of the stimulation was lower than in the presence of calcium. IBMX increased GH release and 45Ca2+ efflux within 15 sec and peak values were reached within 60 sec. (Bu)2cAMP increased GH release both in the presence and absence of extracellular calcium although the magnitude of stimulation was less in the calcium-depleted medium. Efflux of 45Ca2+ was stimulated by (Bu)2cAMP, independently of extracellular calcium. When exposed to 50 mM K+, both GH release and 45Ca2+ efflux increased within 15 sec and reached high peak values within 60 sec, an effect blocked by removal of extracellular calcium. We conclude that GRF and three other GH secretagogues, (Bu)2cAMP, IBMX, and a high extracellular K+ concentration, rapidly increase 45Ca2+ efflux. GH release and 45Ca2+ efflux appear to be tightly coupled with the calcium response perhaps slightly preceding GH release. This tight coupling strengthens the hypothesis that increased Ca2+ activity is directly involved in exocytosis. GRF and (Bu)2cAMP stimulate GH release and 45Ca2+ efflux also in a calcium-free medium, suggesting that mobilization of intracellular calcium is involved in the action of these secretagogues.

Mechanisms underlying the effects of 5-hydroxytryptamine and 5-hydroxytryptophan in pancreatic islets. A proposed role for L-aromatic amino acid decarboxylase.

Microdissected pancreatic islets of noninbred ob/ob mice were used in studies of 5-hydroxytryptamine (5-HT) and 5-hydroxytryptophan (5-HTP) effects on insulin release. The potentiating effect of 4 mM L-5-HTP on glucose-induced insulin release was inhibited by the decarboxylase inhibitors benserazide (100 microM), alpha-monofluoromethyldopa (10 or 100 microM), carbidopa (50 or 500 microM), and NSD 1015 (5 or 50 microM). Activation of L-aromatic amino acid decarboxylase by DL-m-tyrosine (4 mM) or DL-o-tyrosine (4 mM) potentiated glucose-induced insulin release, whereas L-dopa (4 mM) inhibited it. Glucose oxidation was unaffected by L-5-HTP but slightly stimulated by 5-HT. Glucose-induced efflux of 33Pi was reduced by 5-HT but not affected by 5-HTP. These results are compatible with the ideas that 5-HT inhibits glucose-induced insulin release by affecting early steps in the beta-cell stimulus-secretion coupling and that 5-HTP-potentiation of insulin release is probably mediated by the decarboxylase activity but is independent of the 5-HT formed.

Effect of N-methyl-D,L-aspartate on isolated rat somatotrophs.

The effect of excitatory amino acid receptor agonists on GH secretion was tested in isolated male rat somatotrophs. N-Methyl-D,L-Aspartate (NMDA) had a dose-dependent stimulatory effect on GH secretion in perifused somatotrophs. The effect was observed already during the first minute after exposure to NMDA and was reversible after its omission. The effect of 1 microM NMDA was inhibited by the NMDA receptor antagonists 10 microM AP7 and 5 microM MK801, and by 5 microM dextromethorphan. L-Glutamate, 100 microM, and 100 microM kainic acid also stimulated GH secretion. The stimulatory effect of NMDA on GH release was paralleled by an increase in 45Ca efflux and an increase in somatotroph intracellular calcium concentration. Efflux of 86Rb (tracer for potassium) was not affected by NMDA. It is concluded that excitatory amino acids can stimulate GH secretion in rats through a direct effect on the somatotrophs.

Enrichment of type I and type II rat somatotrophs: characterization of growth hormone secretion in vitro.

Enriched fractions of heavily granulated (type II) and sparsely granulated (type I) somatotrophs have been prepared from male Sprague-Dawley rats by Percoll density gradient centrifugation in two steps. After 3 days of culture, basal GH release was 0.116 +/- 0.024 (n = 30) and 0.223 +/- 0.034 ng GH/microgram protein-min (n = 34) in type I and type II cells, respectively (P < 0.05). GH-releasing hormone (GHRH; 0.01-10 nM) stimulated GH release in type II cells, whereas type I cells only responded to higher doses of GHRH (1 and 10 nM). The dynamics of GH release were similar in the two cell types. Type II cells released more GH in absolute values, which may reflect the higher GH content in these cells. The somatostatin analog octreotide (100 pM) reduced basal GH release by 63% in type I cells, but by only 17% in type II cells. Octreotide also had a slightly greater effect on GHRH-induced GH release in type I cells. Both cell types responded to 100 nM GH-releasing peptide-6. We conclude that both type I and type II somatotrophs contribute to GH release, but type II cells are more sensitive to and release more GH when stimulated with GHRH. The role of type I cells may be to boost the initial secretory response at the onset of physiological pulses.

Effects of 5-hydroxytryptamine, dopamine, and aromatic L-amino acids on growth hormone (GH)-releasing factor-stimulated GH release in rat anterior pituitaries.

The importance of monoaminergic mechanisms for the regulation of GH-releasing factor (GRF)-stimulated GH secretion was studied in perifused rat anterior pituitaries. Dopamine (greater than 1 microL) reduced GRF-stimulated GH release, but 5-hydroxytryptamine (5-HT; 1 mL) had no effect. The substrates for L-aromatic amino acid decarboxylase, L-5-hydroxy-tryptophan(L-5-HTP; 10 microM) L-dihydroxyphenylalanine; (1 mM), D,L-o-tyrosine (2 mM), and D,L-m-tyrosine (2 mM), all reduced GRF-stimulated GH release. Inhibition of the L-aromatic amino acid decarboxylase by benserazide (0.1 mM), carbidopa (0.1 mM), or alpha-monofluoromethyldopa (0.1 mM) did not reduce the effect of the decarboxylase substrates on GH secretion. The enzyme inhibitors had no influence on hormone secretion per se. The findings indicate that dopamine may inhibit GRF-induced GH release at the pituitary level and that the precursor amino acids inhibit GH secretion independently of the formation of the corresponding amines.

Initiation of increased pancreatic islet growth in young normoglycemic mice (Umeå +/?).

Pancreatic islets from obese hyperglycemic mice are large and contain a high proportion of normally functioning beta-cells. We have previously shown that young obese mice have an elevated beta-cell proliferation rate at 3 weeks of age. We now wanted to investigate possible factors involved in the initiation of islet growth, including blood glucose, C peptide, glucagon-like peptide-1, vasoactive intestinal polypeptide, and L-5-hydroxytryptophan. We found that the increased beta-cell proliferation on day 20 precedes the rise in blood glucose by 2 days. The islet cell proliferation, measured as the 5-bromo-2'-deoxyuridine labeling index, in 20-day-old lean mice, was enhanced in a dose-dependent manner when glucagon-like peptide-1 or C peptide was injected s.c. for 2 days. L-5-Hydroxytryptophan inhibited the proliferation. C Peptide also increased the islet cell labeling index during islet culture. We conclude that in addition to the effect of glucose, islet proliferation can be triggered by other factors involved in the physiological regulation of increased insulin release. Stimulation of islet proliferation may be related to the actual release of insulin, and C peptide may function as a mediator of such responses.

Effects of 5-hydroxytryptamine on rubidium ion fluxes and insulin release in cultured pancreatic islets.

We have incubated pancreatic islets isolated from noninbred ob/ob mice and NMRI mice for 3 days with or without 5-hydroxytryptamine (5-HT) in the medium and tested the effect of such long term treatment on subsequent insulin release and 86Rb+ accumulation and efflux. Two tenths millimolars of 5-HT abolished insulin release in response to 20 mM glucose. Two tenths millimolars of 5-HT also diminished the ability of islets to accumulate 86Rb+ and the effect of 10 mM glucose on 86Rb+ efflux. One one-hundredth millimolars of 5-HT had no effect on insulin release or 86Rb+ fluxes. Clearly, islets subjected to 5-HT for 3 days at concentrations that do not elicit demonstrable effects in short term incubations show a reduced secretory response. However, the physiological role of the high affinity uptake system for 5-HT in islet cells [Michaelis-Menten constant (Km) = 1.6 microM] remains unknown.

Glucose reduces both Rb+ influx and efflux in pancreatic islet cells.

Microdissected, beta-cell-rich pancreatic islets from ob/ob mice were used in studies of 86Rb+ transport. D-Glucose (20 mM) induced a biphasic reduction in 86Rb+ efflux. The reduction stabilized within 10 min at 34% of the efflux rate at zero glucose. The initial 86Rb+ uptake (5 min) was dose-dependently reduced by ouabain with maximum inhibition at 1 mM. D-Glucose (20 mM) did not affect the ouabain-sensitive 86Rb+ influx but markedly reduced (48%) the ouabain-resistant isotope influx. The results suggest that D-glucose does not affect the Na+/K+ pump in pancreatic beta-cells and that the glucose-sensitive K+-transporting modalities (K+ channels) in the beta-cells can mediate both inward and outward K+ flux.

CD45 phosphatase in Jurkat cells is necessary for response to applied ELF magnetic fields.

Oscillations of free intracellular calcium [Ca2+]i were seen in individual Jurkat cells as response to a 50 Hz, 0.15 mT magnetic field (MF). In contrast, a CD45-deficient Jurkat cell line was unable to respond to MF stimulation. The phosphatase activity of CD45 has been implicated to regulate p56lck tyrosine kinase activity by removing an inhibitory phosphate. By using Jurkat cells that expressed a chimeric molecule, comprising the cytoplasmic phosphatase domain of CD45, the MF induced calcium response was restored. This showed the necessity for an intact signal transduction pathway leading to a calcium increase as a result of stimulation of cells by MF. Thus, our data suggest that the target for the applied MF are molecules involved in early events in the signalling pathway from the T cell antigen receptor.

Strategy for boron neutron capture therapy against tumor cells with over-expression of the epidermal growth factor-receptor.

PURPOSE: Gliomas, squamous carcinomas and different adenocarcinomas from breast, colon and prostate might have an increased number of epidermal growth factor (EGF) receptors. The receptors are, in these cases, candidates for binding of receptor specific toxic conjugates that might inactivate cellular proliferation. The purpose of this study was to evaluate whether it is reasonable to try ligand-dextran based conjugates for therapy. METHODS AND MATERIALS: EGF or TGF alpha were conjugated to dextran and binding, internalization, retention and degradation of eight types of such conjugates were analyzed in EGF-receptor amplified glioma cells. The conjugates were labelled with radioactive nuclides to allow detection and two of the conjugates were carrying boron in the form of carboranyl amino acids or aminoalkyl-carboranes. Comparative binding tests, applying 125I-EGF, were made with cultured breast, colon and prostate adenocarcinoma, glioma and squamous carcinoma cells. Some introductory tests to label with 76Br for positron emission tomography and with 131I for radionuclide therapy were also made. RESULTS: The dextran part of the conjugates did not prevent receptor specific binding. The amount of receptor specific binding varied between the different types of conjugates and between the tested cell types. The dextran part improved intracellular retention and radioactive nuclides were retained for at least 20-24 h. The therapeutical effect improved when 131I was attached to EGF-dextran instead of native EGF. CONCLUSION: The improved cellular retention of the ligand-dextran conjugates is an important property since it gives extended exposure time when radionuclides are applied and flexibility in the choice of time for application of neutrons in boron neutron capture therapy (BNCT). It is possible that ligand-dextran mediated BNCT might allow, if the applied neutron fields covers rather wide areas around the primary tumor, locally spread cells that otherwise would escape treatment to be inactivated.