Glioblastoma multiforme with oculomotor nerve involvement: case report and literature review

Gliomas involving the cranial nerves III-XIII are rare. Even rarer are glioblastomas multiforme (GBMs) with only 10 cases previously reported. Oculomotor nerve involvement was described in only 2 patients. The mechanisms proposed so far include an origin from the nerve itself or an extension within the nerve of a midbrain tumor. We report the case of a 69-year-old man who presented with an isolated left oculomotor nerve palsy. He was found to have a left temporal GBM extended to the frontal lobe. Diagnostics and intraoperative and pathological findings clearly demonstrated a massive infiltration of the cisternal portion of the left oculomotor nerve. We suppose this could be the first case of direct oculomotor nerve invasion by exophytic spread of a supratentorial GBM or by subarachnoid seeding from a temporal tumor. Less probably, it could be the first case of an oculomotor nerve GBM with a temporal lobe invasion.

Intramedullary spinal cord metastasis from an adenoid cystic carcinoma of the external auditory canal: case report

BACKGROUND AND IMPORTANCE

Intramedullary spinal cord metastases (ISCMs) are rare and no cases of ISCM from an adenoid cystic carcinoma (ACC) of the external auditory canal (EAC) have been reported.

CLINICAL PRESENTATION

We report a 54-year old man complaining backpain and worsening myelopathy. He had an ACC of the EAC resected years prior. A spinal MRI demonstrated a contrast-enhancing intramedullary lesion within the conus medullaris. The histopathological diagnosis of the patient was consistent with the patient's primary cancer. At 3 months follow-up, the neurological condition of the patient was unchanged.

CONCLUSIONS

This is the first reported case of ISCM from a primary ACC of the EAC.

Inkjet Printed ZnO Sensors for Early Prostate Cancer Detection by Means of Urine Odor Analysis

In the second half of the 20th century, inkjet printing has rapidly evolved from a mere digital image reproduction technique into a highly versatile materials deposition technology. Recently, inkjet production of metal oxide-based gas sensors (MOS) has emerged, and inkjet sensors have been proposed for different applications. In this context, this paper proposes the adoption of inkjet MOS sensors for urine analysis for the purpose of developing an innovative tool for the early prostate cancer (KP) diagnosis. Based on the results reported in the scientific literature, proving the correlation between urine color and odor alterations and cancer, the study focuses on the analysis by means of MOS sensor array of odors emanated from urine samples from prostate cancer patients versus healthy donors. The results achieved in terms of diagnostic accuracy, sensitivity, and specificity (i.e., about 80%) proved the potentialities of inkjet MOS sensor for the challenging purpose of detection of prostate cancer in its early stages. Resulting significantly more powerful than current KP diagnostic protocol, the approach here presented might become, after validation, a rapid, non-invasive and low-cost screening tool, capable to provide a solution to the problems of patients’ overtreatment and high health spending associated to procedures currently adopted.

Electrodeposition of ZnNi Alloys from Choline Chloride/Ethylene Glycol Deep Eutectic Solvent and Pure Ethylene Glycol for Corrosion Protection

The present work follows the trend to develop non-aqueous electrolytes for the deposition of corrosion resistant ZnNi alloys. It investigates the use of the choline chloride/ethylene glycol (1:2 molar ratio) eutectic mixture and of pure ethylene glycol as solvents for ZnNi electroplating. The electrochemical behavior of Zn and Ni is investigated via cyclic voltammetry, and potentiostatic ZnNi deposition is performed. Ni content is found to be precisely tunable in the 10–20% wt range, which presents the highest industrial interest for corrosion protection. ZnNi coatings obtained are characterized from the morphological and phase composition point of view. Evidence of the formation of a metastable γ ZnNi phase is observed for both choline chloride/ethylene glycol and pure ethylene glycol. Finally, potentiodynamic corrosion tests are performed to assess their corrosion properties.

CZTS thin film solar cells on flexible Molybdenum foil by electrodeposition-annealing route

Abstract

Earth-abundant and non-toxic Kesterite-based Cu2ZnSnS4 (CZTS) thin film solar cells are successfully fabricated on flexible Molybdenum (Mo) foil substrates by an electrodeposition-annealing route. A well-adherent, densely packed, homogeneous, compact, and mirror-like CZT precursor is initially produced through electrodeposition by using a rotating working electrode. Subsequently, the co-electrodeposited CuZnSn (CZT) precursor is sulfurized in quartz tube furnace at 550 °C for 2 h in N2 atmosphere with the presence of elemental sulfur in order to form CZTS. Different characterization techniques like XRD, SEM, HR-TEM, Raman, and Photoluminescence demonstrate that almost phase-pure CZTS formed after sulfurization. A flexible Al/Al-ZnO/i-ZnO/CdS/CZTS/Mo foil solar cell is produced, where CdS is deposited by chemical bath deposition and transparent conducting oxide (TCO) is deposited by DC sputtering. The CZTS solar device shows a 0.55% power conversion efficiency on flexible Mo foil substrate and it constitutes the first prototype of this kind of solar cell produced by electrodeposition-annealing route without any surface modification of the Mo substrate.

Graphic abstract

Metastatic malignant melanoma to the gallbladder. Case report and review of the literature

Solitary metastasis of malignant melanoma (MM) to the gallbladder (GB) is rare and generally originates from skin melanoma. MM is a neoplasm with an often unpredictable course and metastases can potentially affecting all organs. The occurrence of metastasis in the GB is unusual and has only been exceptionally reported in the literature. We describe a case of an 86-year-old man with an isolated MM metastasis located within the GB presenting with symptoms mimicking acute cholecystitis. Anamnestically, he presented a history of malignant melanoma (Clark level III) resected from his left leg 17 years ago. Furthermore we provide a review of the literature with a focus on diagnostic clues to distinguish between primary versus secondary GB MMs and on the best surgical management that should be used.

A Novel Nucleating Agent-Based Technology Resulting in Low Density Rigid Polyurethane Foam for Appliances with Reduced Energy Consumption

Emulsion technology has proven to offer improvements to the performance of rigid polyurethane foam both in terms of general physical properties as well as for insulation performance. The presence of insoluble liquid materials generates a very fine celled structure leading to the above mentioned advantages. Earlier technological developments made in this direction made use of fully or highly fluorinated materials, an approach which became jeopardised because of the unfavourable environmental properties (especially the very high GWP) of this type of materials. A new approach has now been identified which via a similar process, results in polyurethane foam showing improved physical properties, but which doesn't offer negative environmental properties. The improved physical properties include a 10% reduction in minimum stable density in comparison to actual systems available in the market. This paper describes all aspects of this new approach, both in terms of its physical and environmental properties, as well as the final physical properties of the PU foam produced. The overall environmental impact of the different options identified using this approach also will be discussed. Several aspects of the effect of the emulsion technology on the general processing of the foam system will be highlighted. Sourcing, availability and cost impact of the new technology options will also be discussed.

CHF-1024, a DA2/alpha2 agonist, blunts norepinephrine excretion and cardiac fibrosis in pressure overload

We compared the effects of an ACE inhibitor, captopril, with those of a DA2-dopaminergic/alpha2-adrenergic receptor agonist (CHF-1024) on neuroendocrine activation and cardiac fibrosis in a model of pressure-overload hypertrophy. Interrenal aortic stenosis was performed in 89 rats, treated with CHF-1024 (0.33, 2 or 6 mg kg(-1) day(-1)), or captopril (1 g/L). Hemodynamic variables were recorded. Cardiac and renal weights, plasma aldosterone, renin activity and urinary catecholamine excretion were measured, as well as cardiac collagen. Blood pressure was lower in stenotic animals treated with CHF-1024 compared to vehicle (161 +/- 10 vs 219 +/- 10 mmHg, p < 0.01), but LV weight was similar. CHF-1024 elicited a marked dose-dependent attenuation of urinary norepinephrine excretion (1.80 +/- 0.18 in controls compared to 0.40 +/- 0.14 microg/24 h at the highest dose, p < 0.01) and of LV perivascular fibrosis. Captopril provoked a marked hypotension, reduced cardiac and body weights, plasma aldosterone concentration, dopamine excretion and perivascular collagen. The DA2/alpha2 agonist CHF-1024 effectively blunts adrenergic drive and cardiac fibrosis in a rat model of pressure overload.

GABA(B) receptor antagonists elevate both mRNA and protein levels of the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) but not neurotrophin-3 (NT-3) in brain and spinal cord of rats

In this study we show that single, physiologically-active and non-convulsive doses of the three GABA(B) receptor antagonists CGP 36742, CGP 56433A and CGP 56999A increase NGF and BDNF mRNA levels by 200-400% and protein levels by 200-250% in rat neocortex, hippocampus as well as spinal cord. In all areas examined the increase in NGF protein preceded that of BDNF. Peak levels of both neurotrophins are transient and occur between 24 and 72 h, depending on the region. In contrast, NT-3 protein concentrations in the neocortex and hippocampus were decreased significantly to 50% of control values within 48-96 h. The decrease in the spinal cord was less than 30% and did not reach significant levels. These data clearly demonstrate that GABA(B) receptor antagonists induce a specific neurotrophin expression in the central nervous system at physiologically relevant doses, as opposed to the extreme conditions of seizure paradigms. The results are in line with the concept that neuronal neurotrophin synthesis and release in brain are controlled by afferent nerve activity. GABA(B) receptor antagonists could therefore be a valuable new approach to selectively increase endogenous neurotrophin levels in the central nervous system.

Pertussis toxin decreases absence seizures and GABA(B) receptor binding in thalamus of a genetically prone rat (GAERS)

Postsynaptic GABA(B) receptor-mediated events have previously been shown to be reduced by prior treatment with pertussis toxin in rat brain. In the present study genetic absence epilepsy rats from Strasbourg (GAERS) were given single bilateral injections of pertussis toxin (PTx 0.4 microg), denatured-PTx or vehicle saline into the relay nuclei of the thalamus under anaesthesia. After recovery the spike and wave discharge duration (SWD) was monitored for up to 6 days following which the brains were removed and GABA(B) or GABA(A) receptor autoradiography performed on 10 microm transverse sections. By 6 days the SWD of the rats treated with PTx was suppressed by 96% compared with vehicle-injected rats with a significant (62%) reduction even after 1 day. Denatured toxin had no effect at any time. After 6 days GABA(B), but not GABA(A), receptor binding was significantly reduced by 70-80% in the ventrolateral and ventral posteriolateral thalamic nuclei. No changes in other brain regions were detected and denatured toxin failed to alter GABA(A) or GABA(B) receptor binding in any brain region. These data implicate G-protein mechanisms in the generation of SWD in GAERS and support the role of GABA(B) receptors in their induction within the thalamus.

Effects of a DA2/alpha2 agonist and a beta1-blocker in combination with an ACE inhibitor on adrenergic activity and left ventricular remodeling in an experimental model of left ventricular dysfunction after coronary artery occlusion

Renin-angiotensin-aldosterone and sympathetic nervous systems overactivity play a major role in worsening the extent of heart failure. Attenuation of neurohumoral activation with angiotensin-converting enzyme (ACE) inhibitors and beta-blockers has proven beneficial in congestive heart failure. Because ACE inhibition is a recommended treatment for heart failure, this study was designed to test the effects on neurohumoral activation, hemodynamics, and left ventricular (LV) volume of the combination of an ACE inhibitor (delapril) with a DA2-dopaminergic receptor/alpha2-adrenoceptor agonist (CHF-1024) or a beta1-adrenoceptor antagonist (metoprolol) after a moderate to large myocardial infarction (MI) in rats. MI was induced by left coronary artery ligation in 134 rats, and six were not operated on. After 2 months, the animals with ECG evidence of MI were treated for 1 more month with CHF- 1024, 0.33 mg/kg/day or with metoprolol (10 mg/kg/day), delivered through implanted osmotic minipumps, in addition to delapril (6 mg/kg/day) in the drinking water. Daily urinary excretion of norepinephrine (NE) and circulating concentration were measured. Hemodynamic variables were measured, and three-dimensional morphometric analysis was done on the diastole-arrested hearts to quantify infarct size and LV geometry. In conscious animals, delapril alone or with CHF-1024 or metropolol did not modify heart rate or systolic blood pressure. Both combination treatments, however, significantly reduced heart rate in anesthetized animals compared with the group receiving vehicle. Infarct size was not different between treatments, averaging 20-22% of LV volume. The threefold increase of LV chamber volume in infarcted rats was significantly attenuated by delapril alone or with CHF-1024 or metoprolol (-37 to -44%, p<0.05). Treatment with a combination of the ACEi and CHF-1024 tended to normalize the shape of the LV cavity. Urinary NE excretion was unaffected by delapril alone but was reduced by the addition of CHF-1024 or metoprolol. In conclusion, 1 month of treatment with doses of delapril having no hemodynamic effect, reduced LV volume in a model of chronic heart failure. When CHF-1024 or metoprolol was given with delapril, sympathetic activation decreased with no unwanted effects, such as excessive hypotension.

Oxidation of methionine residues in antithrombin. Effects on biological activity and heparin binding

Commercially available human plasma-derived preparations of the serine protease inhibitor antithrombin (AT) were shown to contain low levels of oxidation, and we sought to determine whether oxidation might be a means of regulating the protein's inhibitory activity. A recombinant form of AT, with similarly low levels of oxidation as purified, was treated with hydrogen peroxide in order to study the effect of oxidation, specifically methionine oxidation, on the biochemical properties of this protein. AT contains two adjacent methionine residues near the reactive site loop cleaved by thrombin (Met314 and Met315) and two exposed methionines that border on the heparin binding region of AT (Met17 and Met20). In forced oxidations with hydrogen peroxide, the methionines at 314 and 315 were found to be the most susceptible to oxidation, but their oxidation did not affect either thrombin-inhibitory activity or heparin binding. Methionines at positions 17 and 20 were significantly oxidized only at higher concentrations of peroxide, at which point heparin affinity was decreased. However at saturating heparin concentrations, activity was only marginally decreased for these highly oxidized samples of AT. Structural studies indicate that highly oxidized AT is less able to undergo the complete conformational change induced by heparin, most probably due to oxidation of Met17. Since this does not occur in less oxidized, and presumably more physiologically relevant, forms of AT such as those found in plasma preparations, oxidation does not appear to be a means of controlling AT activity.

Transgenically produced human antithrombin: structural and functional comparison to human plasma-derived antithrombin

Recombinant human antithrombin (rhAT) produced in transgenic goat milk was purified to greater than 99%. The specific activity of the rhAT was identical to human plasma-derived AT (phAT) in an in vitro thrombin inhibition assay. However, rhAT had a fourfold higher affinity for heparin than phAT. The rhAT was analyzed and compared with phAT by reverse phase high-performance liquid chromatography, circular dichroism, fluorophore-assisted carbohydrate electrophoresis (FACE), amino acid sequence, and liquid chromatography/mass spectrography peptide mapping. Based on these analyses, rhAT was determined to be structurally identical to phAT except for differences in glycosylation. Oligomannose structures were found on the Asn 155 site of the transgenic protein, whereas only complex structures were observed on the plasma protein. RhAT contained a GalNAc for galactose substitution on some N-linked oligosaccharides, as well as a high degree of fucosylation. RhAT was less sialylated than phAT and contained both N-acetylneuraminic and N-glycolylneuraminic acid. We postulate that the increase in affinity for heparin found with rhAT resulted from the presence of oligomannose-type structures on the Asn 155 glycosylation site and differences in sialylation.

Comparative efficacy of a DA2/alpha2 agonist and a beta-blocker in reducing adrenergic drive and cardiac fibrosis in an experimental model of left ventricular dysfunction after coronary artery occlusion

Attenuation of neuroendocrine activation may be beneficial in congestive heart failure. Sympathetic nervous system overactivity can be reduced by receptors blockade or by reducing norepinephrine (NE) spillover. This study evaluated and compared the effects of a DA2-dopaminergic receptor/alpha2-adrenoceptor agonist (CHF-1024) and a beta1-adrenoreceptor antagonist in terms of hemodynamics, ventricular remodeling, beta-adrenergic drive, and cardiac fibrosis after myocardial infarction (MI) in rats. MI was induced by left coronary artery ligation in 213 rats, whereas 12 were left unoperated on. After 2 months, the operated-on animals were treated for 1 more month with CHF-1024 at either 0.33 mg/kg/day (low dose) or 1 mg/kg/day (high dose) or with metoprolol (10 mg/kg/day), delivered through implanted osmotic minipumps. Plasma concentration and urinary excretion of NE were measured before the rats were killed. Hemodynamic variables were measured and morphometric analysis was done on the diastole-arrested hearts to quantify left ventricular remodeling and interstitial collagen density. Metoprolol treatment tended to normalize LV end-diastolic pressure (LVEDP). CHF-1024 at either dose, and metoprolol, significantly reduced collagen deposition in LV of infarcted animals (from 8.8 +/- 0.5% LV area in vehicle-treated rats to 6.6 +/- 0.2% or 6.4 +/- 0.2% after the low or high dose of CHF-1024, respectively; p < 0.05). Similarly, CHF-1024 at either dose reduced the plasma concentration of NE (from 224 +/- 53 pg/ml to 60 +/- 7 pg/ml or 87 +/- 13 pg/ml; p < 0.05) and urinary excretion of NE in rats with MI, whereas beta-blockade did not affect these variables. In conclusion, CHF-1024 infused for 1 month to rats with LV dysfunction reduced heart rate, NE spillover, and collagen deposition, without unwanted effects, only appearing at the higher dose. Effective beta-blockade with metoprotol reduced LVEDP with no effects on heart function. Neither DA2/alpha2 stimulation nor beta-blockade altered LV remodeling after coronary artery ligation.

Synthesis and pharmacokinetic behaviour of ester derivatives of 4-isobutylphenyl-2-propionic acid (Ibuprofen) with end-hydroxylated poly(N-vinyl pyrrolidinone) and poly(N-acryloyl morpholine) oligomers

Four derivatives of 4-isobutylphenyl-2-propionic acid (Ibuprofen), in which the drug was bound by ester linkages to poly(ethylene glycols) (PEG 2000-I), monomethoxy poly(ethylene glycols) (PEG 1900-I), poly(N-vinyl pyrrolidinone) (PVP-I) and poly(N-acryloyl morpholine) (PACM-I), all having approximatively the same number average molecular weight (Mn congruent equal to 2000), were prepared and tested for their pharmacokinetic properties after oral administration. It was found that the two end-hydroxylated amphiphilic oligomers of polyvinylic structure, PACM and PVP, whose physico-chemical properties are comparable to those of PEGs especially as regards solvent affinity, have in principle a similar potential as promoieties for preparing oligomeric prodrugs.

Pharmacokinetics of isosorbide dinitrate in healthy volunteers after 24-hour intravenous infusion

No studies have examined the pharmacokinetics of isosorbide dinitrate (ISDN) after infusion of long duration, even though such infusions are used in patients. We therefore measured ISDN and its active metabolites, isosorbide-5-mononitrate (IS5MN) and isosorbide-2-mononitrate (IS2MN), in plasma of 9 healthy volunteers who received a continuous intravenous infusion of ISDN for 24 hours at a dose rate that lowered diastolic blood pressure by 10% during the first 30 minutes of infusion. All subjects tolerated the infusion except one who experienced intolerable headache. Five subjects received 1 microgram.min-1.kg-1, one 2 micrograms.min-1.kg-1, and two 4 micrograms.min-1.kg-1 ISDN, whereas the full rate of 6 micrograms.min-1.kg-1 was used continuously in one subject. At all infusion rates the plasma concentrations of ISDN were higher at 24 hours than at earlier times, suggesting that a steady-state condition had not been reached at that time. The same was true for the mononitrate metabolites, which reached higher plasma concentrations and were cleared more slowly than the parent compound after the end of the infusion. Apparent elimination half-lives of ISDN, IS2MN, and IS5MN were 67 +/- 10 minutes, 115 +/- 13 minutes, and 272 +/- 38 minutes, respectively. Comparison of low-rate infusions (1 and 2 micrograms.min-1.kg-1) with high-rate infusions (4 and 6 micrograms.min-1.kg-1) showed that the plasma concentration ratios at 24 hours of mononitrate metabolites to parent drug and apparent plasma clearance of ISDN were almost halved at the higher infusion rates.

Opposite effects of GABAB receptor antagonists on absences and convulsive seizures

In Wistar rats with spontaneous non-convulsive absence epilepsy, absence seizures were dose dependently suppressed by intraperitoneal administration of the GABAB receptor antagonists CGP 36742, 50-400 mg/kg, and CGP 56999, 0.25-0.75 mg/kg, and by bilateral microinjections of the same compounds into the lateral nuclei of the thalamus. In rats susceptible to audiogenic seizures, intraperitoneal administration of both GABAB receptor antagonists, at doses which suppressed absence seizures, facilitated the elicitation of sound-induced tonic seizures. In non-epileptic control rats, intraperitoneal injections of higher doses of CGP 36742 (800-2400 mg/kg) and CGP 56999 (3-6 mg/kg) induced delayed clonic convulsions, which were suppressed by pretreatment with baclofen. c-Fos protein was expressed after GABAB receptor antagonist-induced seizures in the cortex, hippocampus, amygdala, perirhinal and piriform cortex. Intra-cortical and hippocampal microinfusion of both GABAB receptor antagonists produced focal seizures. In conclusion, GABAB receptor antagonists suppress non-convulsive absence seizures by blocking thalamic GABAB receptors, while they induce convulsions in cortical and limbic structures.

Binding characteristics of gamma-hydroxybutyric acid as a weak but selective GABAB receptor agonist

The aim of this study was to reexamine the concept that gamma-hydroxybutyric acid (GHB) is a weak but selective agonist at gamma-aminobutyric acidB (GABAB) receptors, using binding experiments with several radioligands. Ki values of GHB were similar (approximately equal to 100 microM) in three agonist radioligand assays for GABAB receptors, [3H]baclofen (beta-para-chlorophenyl-gamma-aminobutyric acid), [3H]CGP 27492 (3-aminopropyl-phosphinic acid) and [3H]GABA, in the presence of the GABAA receptor agonist isoguvacine with rat cortical, cerebellar and hippocampal membranes. In competition experiments between GHB and the GABAB receptor antagonist, [3H]CGP 54626 (3-N [1-{(S)-3,4-dichlorophenyl}-ethylamino]-2-(S)-hydroxypropyl cyclo-hexylmethyl phosphinic acid), the IC50 values were significantly increased with 300 microM of 5'-guanyl-imidodiphosphate (Gpp(NH)p), which suggested that guanine nucleotide binding proteins (G-proteins) modulate GHB binding on GABAB receptors. The inhibition by GHB of [3H]CGP 27492 binding in cortical membranes was not altered in the presence of 0.3 or 3 mM of the two GHB dehydrogenase inhibitors, valproate and ethosuximide. Thus, GHB is not reconverted into GABA by GHB dehydrogenase. Taken together, the results of this study demonstrated that GHB is an endogenous weak but selective agonist at GABAB receptors.

Regional differences of the inhibition of GABAB ligand binding by the GTP analogue Gpp(NH)p

In order to determine whether the interactions between GABAB receptors and G-proteins differ in several brain areas, we have used the reduction in high-affinity GABAB binding by the GTP analogue Gpp(NH)p as an internal assay marker for G-protein linkage to GABAB receptors. The results indicate that Gpp(NH)p inhibits the binding of the GABAB receptor agonist [3H]CGP 27492 (80 to 95%) in a biphasic manner between 0.1 nM and 1 mM. The IC50 for high-affinity sites is significantly higher in cerebellum (70 nM, 53% of binding sites) than in cortex, hippocampus, corpus striatum and thalamus (15-30 nM, 63-73% of binding sites). The IC50S of the low-affinity sites in hippocampus and cortex (170 microM and 210 microM, respectively) were significantly higher than the IC50S in cerebellum, thalamus and corpus striatum (18-39 microM). All these binding sites are sensitive to pertussis toxin (PTX; 7-15 micrograms/mg protein), implicating that they are linked either to Gi or to Gzero proteins. The two binding sites observed (high affinity, nM and low affinity, microM for Gpp(NH)p) and the regional dependence in affinity of these sites may originate either from different GABAB receptor subtypes, different G-proteins or different coupling mechanisms between G-proteins and GABAB receptors. Whereas the PTX site of G-protein linked to GABAB receptors changes with age [24], the GTP binding site does not differ between peripubertal rats (5-6 weeks) and adults rats (10-12 weeks).

Antithrombin-heparin affinity reduced by fucosylation of carbohydrate at asparagine 155

The two human plasma antithrombin isoforms, alpha and beta, differ in glycosylation at asparagine 135. Only the alpha form carries carbohydrate at this position and has lower affinity for heparin than the beta form. We previously found additional heterogeneity in a recombinant N135Q antithrombin variant, evidenced by two isoforms with a 2-fold difference in heparin affinity [Turko, I. V., Fan, B., & Gettins, P. G. W. (1993) FEBS Lett. 335, 9-12]. To test whether this heterogeneity of heparin affinity results from specific glycosylation differences, we have determined the carbohydrate composition at the three remaining glycosylation sites, asparagine residues 96, 155, and 192, in each of the two N135Q isoforms, by a combination of peptide fragmentation and electrospray mass spectrometry. Patterns of glycosylation at residues 96 and 192 were similar for each isoform and showed the presence of mono-, bi-, and triantennary complex carbohydrate, as well as fucosylation of all types of chains. At position 155, however, there was a marked difference between the isoforms, with the form with lower heparin affinity being 97% fucosylated at this position, whereas the form with higher affinity for heparin was not fucosylated. Other differences in carbohydrate type showed no strong correlation between the two isoforms. We conclude that formation of the two heparin-affinity isoforms of N135Q antithrombin results from the specific difference in fucosylation at residue 155, which may result in different structural properties of the carbohydrate. Consistent with these findings was the elimination of heparin-affinity heterogeneity in a double N135Q-N155Q variant antithrombin. It is possible that fucosylation of antithrombin may occur in vivo as a means of modifying the physiological properties of the antithrombin through alteration of the amount of antithrombin bound to surface heparin-like species.

Ultrastructural evidence of thyroid damage in amiodarone-induced thyrotoxicosis

Amiodarone-induced thyrotoxicosis occurs in 2-12.1% of patients on chronic amiodarone treatment. In most cases its pathogenesis is related to iodine overload in the presence of preexisting thyroid abnormalities, such as multinodular or diffuse goiter or autonomous nodule. A minority of patients show apparently normal glands or pictures of non-autoimmune thyroiditis. However, there is recent evidence of a direct toxic effect of amiodarone, with consequent release of iodothyronines into the circulation. We report a patient with amiodarone-induced thyrotoxicosis with toxic thyroid effects demonstrated by electron microscopy in a fine-needle aspiration biopsy. There were three main pathologic findings: multilamellar lysosomal inclusions, intramitchondrial glycogen inclusions--both ultrastructural findings indicating thyroid cell damage--and a microscopic morphological pattern of thyroid cell hyperfunction. No inflammatory changes were found. Plasma thyroglobulin levels were high. The patient proved to be a non responder to simultaneous administration of methimazole (starting dose 30 mg/day) and potassium perchlorate (1000 mg/day for 40 days), while still taking amiodarone, thus providing evidence against a possible pathogenetic role of iodine overload. Dexamethasone (starting dose 3 mg/day) was added to methimazole. After three months euthyroidism had been restored and plasma thyroglobulin level substantially decreased. Subsequent subclinical hypothyroidism developed, which persisted after stopping antithyroid treatment and required substitution treatment with levothyroxine. In view of the primary role of lysosome function in the proteolysis of thyroglobulin molecules and of the energy-requiring carrier-mediated transport of monoiodotyrosine across the lysosomal membrane for iodine salvage and reutilization, we suggest that the pathological lysosomal and mitochondrial changes observed could be an ultrastructural marker for subsequent hypothyroidism in amiodarone-induced thyrotoxicosis. Our observations suggest the usefulness of ultrastructural thyroid evaluation and serial plasma thyroglobulin determinations to thoroughly evaluate the underlying pathogenetic mechanisms in amiodarone-associated thyrotoxicosis with apparently normal thyroid glands. Moreover, more knowledge of its pathogenesis could improve both prognostic stratification and treatment guides.

Phosphinic acid analogues of GABA. 2. Selective, orally active GABAB antagonists

In 1987, 25 years after the synthesis of the potent and selective GABAB agonist baclofen (1), Kerr et al. described the first GABAB antagonist phaclofen 2. However, phaclofen and structurally similar derivatives 3-5 did not cross the blood-brain barrier and hence were inactive in vivo as central nervous system agents. As a consequence, the therapeutic potential of GABAB antagonists remained unclear. In exploring GABA and baclofen derivatives by replacing the carboxylic acid residue with various phosphinic acid groups, we discovered more potent and water soluble GABAB antagonists. Electrophysiological experiments in vivo demonstrated that some of the new compounds were capable of penetrating the blood-brain barrier after oral administration. Neurotransmitter release experiments showed that they interacted with several presynaptic GABAB receptor subtypes, enhancing the release of GABA, glutamate, aspartate, and somatostatin. The new GABAB antagonists interacted also with postsynaptic GABAB receptors, as they blocked late inhibitory postsynaptic potentials. They facilitated the induction of long-term potentiation in vitro and in vivo, suggesting potential cognition enhancing effects. Fifteen compounds were investigated in various memory and learning paradigms in rodents. Although several compounds were found to be active, only 10 reversed the age-related deficits of old rats in a multiple-trial one-way active avoidance test after chronic treatment. The cognition facilitating effects of 10 were confirmed in learning experiments in Rhesus monkeys. The novel GABAB antagonists showed also protective effects in various animal models of absence epilepsy.

On the suitability of urethane bonds between the carrier and the drug moiety in poly(ethyleneglycol)-based oligomeric prodrugs

Some poly(ethyleneglycol) derivatives of propranolol were prepared, in which the drug molecule was linked to the oligomeric carrier via urethane bonds in order to study the suitability of this bond as a linkage between the carrier and the drug moiety in oligomeric prodrugs. For comparison purposes also ethanol- and butanol-based prodrugs of propranolol were prepared, with the same linkage between drug and promoiety. The urethane compounds were obtained by condensation via N,N'-carbonyldiimidazole. None of these compounds gave rise to appreciable blood concentrations of propranolol after oral administration, thus suggesting in this particular case, a relative in vivo resistance of urethane bonds towards cleavage.

Pharmacokinetic results on naproxen prodrugs based on poly(ethyleneglycol)s

Five prodrugs of S(+)-2-(6-methoxy-2-naphthyl)propionic acid (naproxen), in which the drug was bound by ester linkages to diethyleneglycol (I), triethyleneglycol (II), octanediol (III), butyl-triethyleneglycol (IV), and butyl-tetraethyleneglycol (V), respectively, were prepared and tested for their pharmacokinetic properties after oral administration. It was found that bioavailabilities decreased in the order, and in all cases were lower than that of the free drug.

Recombinant human thyroid stimulating hormone: development of a biotechnology product for detection of metastatic lesions of thyroid carcinoma

We have genetically engineered a cell line, and developed a reproducible process, for the expression and purification of biologically active recombinant human thyroid stimulating hormone (rhTSH).rhTSH was expressed by co-transfecting a human alpha-subunit cDNA with a human beta-subunit partial genomic clone into Chinese Hamster Ovary (CHO) cells. Stable transfectants which expressed high levels of rhTSH were selected, and subsequently cultured on microcarrier beads. The rhTSH-containing media, produced under serum-free conditions, was clarified and purified by a combination of ion exchange, dye and gel filtration chromatographies. Individual step recoveries were greater than 90% with the exception of a very conservative pooling of the final gel filtration step (78% recovery) that resulted in a cumulative yield of 54% for the purification process. Purity of the final bulk material was judged to be > 99% by SDS polyacrylamide gel electrophoresis (SDS-PAGE), reverse phase HPLC, and size exclusion chromatography. Initial characterization of the oligosaccharide composition indicated the presence of partially sialylated bi- and triantenary complex oligosaccharides. Purified rhTSH was active in a thyroid membrane bioactivity assay with a specific activity of 8.2 IU/mg. The in vivo activity of rhTSH in cynomolgus monkeys appeared to be equal to or greater than that reported for bovine TSH (bTSH) in human subjects. The rapid clearance phase half-life of rhTSH was approximately 35 minutes while the post-distribution phase half life was approximately 9.8 hours. Furthermore, the monkeys showed cumulative increases in minimum plasma rhTSH levels when given three daily intramuscular (IM) rhTSH injections; a phenomenon not observed when bTSH had been administered to humans. The rhTSH showed no evidence of toxic or adverse effects when administered at doses up to 7.2 IU/kg and 0.52 IU/kg in rat and monkey, respectively. These are 50X and 4X multiples of the bTSH doses of 0.143 IU/kg (10 IU/70kg) previously administered to humans.

Differential inhibition of human secretory and cytosolic phospholipase A2

The roles and relative contributions of secretory and cytosolic phospholipases A2 in physiology and pathology are not precisely known. In a search for differential inhibitors of these enzymes, which could serve as tools to clarify this issue, we evaluated the potencies of reference compounds and three series of new compounds, viz. substrate analogues, 1,2-amino alcohols and enolized beta-tricarbonyl derivatives, as inhibitors of secretory phospholipase A2 from human polymorphonuclear leukocytes (sPLA2) and of cytosolic phospholipase A2 from human U937 cells (cPLA2). With few exceptions, the compounds selected are potent inhibitors of sPLA2 with IC50 values (concentration inhibiting 50%) in the low micromolar range. Inhibition of cPLA2 was only observed with some phosphate-free substrate analogues, with 1,2-amino alcohols and two of seven reference compounds. These results suggest that inhibition of secretory and of cytosolic phospholipases A2 are independent effects. Several inhibitors could be identified with a marked selectivity for sPLA2.

Pharmacokinetics of diltiazem and a new analogue, LR-A/113, in the conscious rat

Pharmacokinetics and metabolism of diltiazem and a new analogue, LR-A/113, have been studied in the rat. Conscious rats, with the jugular vein cannulated, received the compounds by intravenous (3 mg/kg body weight) or oral (50 mg/kg body weight) route. Parent compounds and their N-demethyl and N-deacetyl metabolites were assayed at serial times in blood. Half-life of elimination of diltiazem was significantly shorter than that of LR-A/113, both after oral (37 +/- 9 vs 59 +/- 26 min) and intravenous (29 +/- 12 vs 57 +/- 16 min) administration. N-deacetyl-diltiazem concentrations after oral administration were higher than the parent compound and N-demethyldiltiazem; LR-A/113 blood concentrations were higher than those of its two metabolites. Metabolites were measurable only in traces after intravenous administration. Oral bioavailability was very low, 3.5% for diltiazem and 4.2% for LR-A/113. In conclusion, the substitution of a methyl by an isopropyl group appears to slow in vivo elimination of the analogue of diltiazem, LR-A/113.

Beta-blocking effect of propafenone based on spectral analysis of heart rate variability

RR variability was analyzed in 15 patients with ventricular arrhythmias to evaluate whether the antiarrhythmic action of propafenone is associated with alteration of neural control mechanisms. Before drug administration, spectral analysis of RR variability was characterized by 2 major components at low and high frequency, which are considered to reflect sympathetic and parasympathetic modulation of the heart period. After propafenone (600 to 900 mg/day), there was a marked reduction in RR variance (826 +/- 184 to 412 +/- 77 ms2; p < 0.05), although the mean RR interval was unchanged. The drug significantly reduced the low-frequency component (52 +/- 6 to 28 +/- 4 nu) and augmented the high-frequency component (39 +/- 6 to 55 +/- 5 nu). As a result, the low-/high-frequency ratio (an index of sympathovagal balance) decreased from 2.0 +/- 0.4 to 0.6 +/- 0.1. A positive correlation between serum levels and drug-induced changes in the low-frequency component was also observed. Furthermore, the increase in the low-frequency component induced by tilt (53 +/- 5 to 79 +/- 3 nu) was markedly attenuated after drug administration (27 +/- 5 to 54 +/- 7 nu). Thus, propafenone administration is associated with changes in spectral components that are consistent with a beta-blocking effect of the drug.

Differing effects of α-difluoromethylornithine and CGP 40116 on polyamine levels and infarct volume in a rat model of focal cerebral ischaemia

Focal cerebral ischaemia was induced in rats by occlusion of the left middle cerebral artery. Two days later, infarct volume was determined by magnetic resonance imaging and the concentrations of the polyamines putrescine (PU), spermine and spermidine by HPLC. In control (occluded) animals, PU levels were elevated in infarcted and non-infarcted areas of the left hemisphere. Treatment with the ornithine decarboxylase (ODC) inhibitor alpha-difluoromethylornithine, prevented the ischaemia-induced increase in tissue PU without affecting infarct volume. Conversely, administration of the N-methyl-D-aspartate (NMDA) receptor antagonist CGP 40116 decreased cortical infarction without changing the tissue content of PU. We conclude that there is no direct link between NMDA receptor activation and brain PU, or PU and post-ischaemic tissue damage, and that inhibitors of ODC are not cerebroprotective in this animal model of stroke.

GABAB receptor antagonists: potential new anti-absence drugs

The availability of new antagonists of the GABAB receptor which readily cross the blood-brain barrier has made it possible to investigate the role of GABAB-receptor-mediated transmission in the control of spike-and-wave discharges (SWD) in a strain of rats (GAERS) with genetic absence epilepsy. Systemic administration of R-Baclofen, a GABAB agonist, increased the duration of SWD, or elicited SWD-like oscillations in the cortical EEG of non-epileptic control rats. Conversely, administration of CGP 35348, a GABAB antagonist, either i.p. or p.o., dose-dependently suppressed the spontaneous SWD, as well as the SWD aggravated by concomitant injection of various GABAmimetic drugs, GHB, or anti-convulsants known to exacerbate absence seizures. These results demonstrate the involvement of GABAB-mediated neurotransmission in the development of SWD in generalized non-convulsive epilepsy. GABAB antagonists may thus be considered to be potentially specific anti-absence drugs.

Experimental absence seizures: potential role of gamma-hydroxybutyric acid and GABAB receptors

We have investigated whether the pathogenesis of spontaneous generalized non-convulsive seizures in rats with genetic absence epilepsy is due to an increase in the brain levels of gamma-hydroxybutyric acid (GHB) or in the rate of its synthesis. Concentrations of GHB or of its precursor gamma-butyrolactone (GBL) were measured with a new GC/MS technique which allows the simultaneous assessment of GHB and GBL. The rate of GHB synthesis was estimated from the increase in GHB levels after inhibition of its catabolism with valproate. The results of this study do not indicate significant differences in GHB or GBL levels, or in their rates of synthesis in rats showing spike-and-wave discharges (SWD) as compared to rats without SWD. Binding data indicate that GHB, but not GBL, has a selective, although weak affinity for GABAB receptors (IC50 = 150 microM). Similar IC50 values were observed in membranes prepared from rats showing SWD and from control rats. The average GHB brain levels of 2.12 +/- 0.23 nmol/g measured in the cortex and of 4.28 +/- 0.90 nmol/g in the thalamus are much lower than the concentrations necessary to occupy a major part of the GABAB receptors. It is unlikely that local accumulations of GHB reach concentrations 30-70-fold higher than the average brain levels. After injection of 3.5 mmol/kg GBL, a dose sufficient to induce SWD, brain concentrations reach 240 +/- 31 nmol/g (Snead, 1991) and GHB could thus stimulate the GABAB receptor. Like the selective and potent GABAB receptor agonist R(-)-baclofen, GHB causes a dose-related decrease in cerebellar cGMP. This decrease and the increase in SWD caused by R(-)-baclofen were completely blocked by the selective and potent GABAB receptor antagonist CGP 35348, whereas only the increase in the duration of SWD induced by GHB was totally antagonized by CGP 35348. The decrease in cerebellar cGMP levels elicited by GHB was only partially antagonized by CGP 35348. These findings suggest that all effects of R(-)-baclofen are mediated by the GABAB receptor, whereas only the induction of SWD by GHB is dependent on GABAB receptor mediation, the decrease in cGMP being only partially so. Taken together with the observations of Marescaux et al. (1992), these results indicate that GABAB receptors are of primary importance in experimental absence epilepsy and that GABAB receptor antagonists may represent a new class of anti-absence drugs.

Identification of propafenone metaboliser phenotype from plasma and urine excretion data

The aim of the study was to validate a test based on analyses of urine to identify the propafenone metaboliser phenotype during routine chronic therapy. Twenty seven patients chronically treated with propafenone were studied. A debrisoquine test was performed in 10. Propafenone and its metabolites in plasma and urine were measured by HPLC. Propafenone, 5-hydroxypropafenone and N-depropylpropafenone concentrations in plasma were 1.09, 0.182 and 0.101 ng.ml-1, respectively. Total recovery of the administered dose in urine was 30.7%. Two patients were identified as PM, based on the result of the debrisoquine test (log D/4OHD of 1.26 and 1.36). This finding was confirmed by the propafenone metabolic ratio in urine, but the plasma data did not permit clearcut separation of the phenotypes. Propafenone/5-hydroxypropafenone in plasma was not a good predictor of metabolizer phenotype. Although the number of patients who completed all three tests was limited, it is concluded that analysis of propafenone/5-hydroxypropafenone in urine collected between two consecutive doses at steady-state is more practical than the debrisoquine test and more specific than determining the propafenone/5-hydroxypropafenone ratio in plasma, for identification of the propafenone metaboliser phenotypes.

Reversal by apomorphine of the gabaculine-induced GABA accumulation in mouse cortex

To test the assumption that in the mice cortex the rate of accumulation of gamma-aminobutyric acid (GABA) after irreversible inhibition of 4-aminobutyrate: 2-oxoglutarate aminotransferase (EC 2.6.1.19; GABA-T) represents an index of GABA turnover, we examined whether the reversal of the gabaculine-induced accumulation of GABA elicited by apomorphine was due to a decrease in GABA turnover or to a modulation of the activity of the GABA-T inhibitor. Therefore, we simultaneously measured the action of apomorphine on gabaculine-induced accumulation of GABA and on GABA-T activity. In vitro, apomorphine (3 and 30 microM) did not alter the concentration-dependent inhibition of GABA-T by gabaculine. Ex vivo, apomorphine (2 x 0.5 mg/kg s.c.) markedly decreased (69%) gabaculine-induced (150 mg/kg i.p.) accumulation of GABA. This drug had no direct effect on GABA-T activity, but significantly reduced from 83 to 71% the inhibition of GABA-T by gabaculine. The linear correlation found between GABA levels and GABA-T activity allowed the quantification of the decrease in GABA turnover elicited by apomorphine. The results showed that apomorphine decreased significantly (P less than 0.001) the rate of GABA synthesis from 7.48 to 3.36 micromol GABA/g per h, if the partial reversal of gabaculine-induced inhibition of GABA-T is considered and 2.44 micromol/g per h if not. Apomorphine effect on GABA accumulation is mainly due to a decrease of the rate of GABA synthesis and to a lesser extent to a reversal of the inhibitory activity of gabaculine. Thus, inhibition of GABA-T by gabaculine is a sensitive and reliable method for the estimation of the rate of synthesis.

[Interactions of GABAergic and catecholaminergic neurotransmissions. Effects of dopaminergic and noradrenergic agonists and antagonists on GABA turnover]

The effects of specific D1 and D2 agonists and antagonists on GABA turnover in four brain structures have been studied. GABA turnover was estimated by measuring the accumulation of GABA after GABA-T inhibition with gabaculine. Stimulation of DA receptors by apomorphine, a mixed D1 and D2 agonist or by (+/-)2-(N-phenylethyl-N-propyl)amino-5-hydroxytetraline, a selective agonist of D2 receptors, dose-dependently reduced GABA turnover. Both agonists had no effect on GABA levels. S(-)sulpiride, a selective D2 antagonist, had no effect on either GABA levels or GABA turnover. However, sulpiride antagonized the reduction of GABA turnover produced by apomorphine or (+/-)2-(N-phenylethyl-N-propyl)amino-5-hydroxytetraline. By contrast, SKF 38393, a selective D1 agonist, did not appear to influence GABA-mediated inhibitory neurotransmission. SCH 23390, a D1 antagonist, which by itself had no effect on GABA levels and only slightly decreased GABA turnover, did not antagonize the effect of apomorphine. On the contrary, SCH 23390, slightly, but significantly increased the reduction in GABA turnover produced by apomorphine. Furthermore, idaxozan, an alpha 2-antagonist, antagonized the reduction of GABA turnover produced by the alpha 2-agonist clonidine, but did not prevent the effect of apomorphine on GABA turnover. Thus, the tonic inhibition exerted by DA on GABA-mediated neurotransmission seems to be mainly controlled by D2 receptors.

Gamma-vinyl GABA: comparison of neurochemical and anticonvulsant effects in mice

Biochemical and pharmacological effects of gamma-vinyl GABA (Vigabatrin, GVG), and irreversible enzyme-activated inhibitor of 4-aminobutyrate: 2-oxoglutarate aminotransferase (EC 2.6.1.19; GABA-T), were measured in mice. This anticonvulsant produced a time- and dose-dependent elevation of the GABA, phenylalanine and lysine contents of cortical tissue and simultaneously decreased glutamate, aspartate and alanine levels. In addition, GVG caused a biphasic change in glutamine concentrations (a decline 1-4 hours after administration, followed 20 hours later by an increase). Moreover, we found a new, as yet unidentified amino acid in the brain eluting with the same retention time as alpha-aminoadipic acid from an HPLC cation-exchange column. The level of this novel chemical entity was greatly increased by GVG 20 hours after injection of the drug. At all tested intervals between 1 and 60 hours after injection, GVG was ineffective against maximal electroshock. The GABA-T inhibitor dose-dependently protected mice against isoniazid-induced seizures, simultaneously causing an increase in brain GABA concentrations. However, this apparent correlation applied only until 4 hours after treatment. To better define the anticonvulsant profile of GVG, groups of mice were treated, 1, 2, 4, and 24 hours prior to challenge with convulsant doses of strychnine, pentetrazole (PTZ), and picrotoxin, and brain amino acid levels, including brain concentrations of GVG, were measured. In all instances, the time dependency of the anticonvulsant effects of GVG and of increases in brain GABA levels differed. Amino acid concentrations in animals treated only with GVG were similar to those in animals given GVG and a chemical convulsant. GVG showed no selectivity for seizures produced by impairment of GABA-ergic neurotransmission. Although GVG is an effective GABA-T inhibitor, it apparently affects several other pyridoxal-phosphate-dependent cerebral enzymes and/or interacts with other neurotransmitter systems as well.

Evaluation of the anticonvulsant and biochemical activity of CGS 8216 and CGS 9896 in animal models

CGS 8216, a benzodiazepine-receptor ligand with inverse agonistic properties, and CGS 9896, which possesses partial agonistic or mixed agonist-antagonist properties were compared in a number of epilepsy models. The effect of CGS 9896 on the decrease in GABA levels induced by isoniazid was also investigated. CGS 9896 inhibited the kindling process in rats in that it delayed the development of overt seizures and the increase in the duration of afterdischarges. In a genetic rat model characterized by absence-like EEG patterns, CGS 9896 dose-dependently suppressed these spontaneously occurring discharges, while CGS 8216 had no effect. However, CGS 8216 antagonized the anticonvulsant action of CGS 9896. CGS 9896 protected mice against seizures induced by beta-vinyllactic acid, whereas CGS 8216 shortened the latency period before convulsions occurred. CGS 9896 retarded the onset of convulsive fits caused by isoniazid without preventing the decrease in GABA levels produced by that drug. These results confirm the anticonvulsant activity of CGS 9896 and demonstrate the inverse agonistic activity of CGS 8216. The profile of CGS 9896 in the above tests suggests that it might be an effective anticonvulsant, primarily in absence-type seizures.