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B Pirotte

Publications and source records attributed to B Pirotte.

At least 73 records · Page 4Linked to original sources
PubMed1995

Chronic intrathecal baclofen in severely disabling spasticity: selection, clinical assessment and long-term benefit.

Flexor and extensor spasms associated with severe spasticity frequently cause pain and suffering in neurologically impaired patients, and greatly interfere with comfort and activities. When high doses of oral medications are necessary to keep the symptoms under control and are poorly tolerated, the long-term spinal-selective intrathecal infusion of baclofen by means of implanted drug pump and catheter is a safe, efficient and reversible alternative to destructive surgical procedures. Between September 1991 and March 1995, intrathecal baclofen was infused in 18 selected patients out of a series of 42 severely disabled spastic cases. We report here our preliminary experience with the criteria of selection, the initial intrathecal bolus test and the long-term benefit of the selected patients. Our results confirm the dramatic immediate and long-term benefit reported in other series. After a period of treatment of 1 to 42 months, 13 patients had a complete disappearance of their spastic symptoms without any oral treatment, one patient kept unchanged clonus despite the use of low-dose oral treatment and another one a severe, not improved dysuria although in both of them hypertonia and spasms were abolished. Finally, 2 patients had important joint stiffness slightly impairing the benefit from the treatment. None of the 18 patients had central side-effects related to baclofen. With time, a slight increase in daily dose (inferior to 10%) was necessary in most patients.

Adult↗
PubMed1994

Cationic and secretory effects of BPDZ 44 and diazoxide in rat pancreatic islets.

The present study aimed at comparing the effects of low concentrations of BPDZ 44, a new pyridothiadiazine derivative, and diazoxide on 86Rb outflow, 45Ca outflow, 45Ca uptake and insulin release from rat pancreatic islets. Both drugs caused similar modifications, but the effects of BPDZ 44 on the cationic and secretory events were much more marked than those of diazoxide. It is suggested that BPDZ 44 could be valuable tool for further studies of the KATP channels.

Animals↗
PubMed1994

A pyridothiadiazine (BPDZ 44) as a new and potent activator of ATP-sensitive K+ channels.

The present study was undertaken to characterize the effects of [3-(1',2'-dimethyl-propyl)amino-4H-pyrido[4,3-e][1,2,4]thiadiazine 1,1-dioxide] (BPDZ 44), a new pyridothiadiazine derivative, on ionic and secretory events in rat pancreatic islets. The drug increased the rate of 86Rb outflow regardless of the extracellular glucose concentration. The effects of BPDZ 44 on 86Rb outflow persisted in the absence of extracellular Ca2+ but were abolished by glibenclamide. BPDZ 44 markedly decreased 45Ca outflow and insulin output from islets perifused in the presence of 16.7 mM glucose and extracellular Ca2+. The drug did not affect the increase in 45Ca outflow mediated by K+ depolarization. Lastly, in single B-cells, BPDZ 44 inhibited the glucose but not the KCl-induced rise in cytosolic Ca2+ concentration ([Ca2+]i). These data suggest that BPDZ 44 inhibits the insulin releasing process by activating ATP-sensitive K+ channels. This K+ channel activation will lead to a decrease in Ca2+ influx and reduction in [Ca2+]i.

Adenosine Triphosphate↗
PubMed1994

PET in stereotactic conditions increases the diagnostic yield of brain biopsy.

We have recently described a technique allowing routine integration of PET scan data in the planning of stereotactic brain biopsy [Levivier et al:, Neurosurgery, 1992; 31:792-797]. We now report our results in a consecutive series of 38 patients that underwent combined FDG-PET and CT-guided stereotactic biopsy between June 1991 and January 1993. Stereotactic procedures were performed according to a standard protocol in which two biopsy trajectories were used whenever possible. This yielded to a total of 78 trajectories. In 31 patients, at least 1 trajectory was defined using an abnormality visualized on PET. The histological diagnosis was obtained in all cases. The diagnostic yield of each trajectory according to the FDG uptake of PET and contrast enhancement on CT showed that most low-grade tumors were found in hypometabolic/hypodense areas, glioblastomas were all diagnosed in areas with increased FDG uptake and contrast enhancement on CT while data for anaplastic astrocytomas were heterogeneously distributed. In the present series, 6 targets defined on CT were nondiagnostic; this never occurred when targets were defined on FDG-PET. In one case of anaplastic astrocytoma, the diagnosis was only made using a target defined on PET in a normal CT area; the second trajectory was made in a contrast-enhanced area on CT and was nondiagnostic. Because only structural images such as CT or MRI are available preoperatively, we analyzed separately the benefit of FDG-PET-guided biopsy in patients who have either an enhanced- or a nonenhanced lesion on CT. CT-enhanced lesions were found in 27 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Evaluation of the inhibitory activity on serine and aspartic proteases of 4-amino-4H-1,2,4-triazole and 5-aminothiazole derivatives structurally related to beta-lactam antibiotics.

Twenty new derivatives of 4-amino-4H-1,2,4-triazole and 5-aminothiazole have been examined for their inhibitory potential towards serine and aspartic proteases. Upon prolonged incubation with enzyme, the phenylacetylaminothiazolium salts exhibit progressive, time-dependent inhibition of chymotrypsin according to a first-order process. The formation of a tetrahedral transition state-like complex by attack of the active-site serine at the C2-position of the pseudobase form of the thiazolium may be responsible for the observed effect. Triazolium salts appeared to be simple competitive inhibitors of this enzyme, effective in the mM range concentration. Poor inhibitions of trypsin and pepsin were also obtained in the triazolium series. In spite of their structural analogy with beta-lactams, the selected derivatives failed to inhibit human leucocyte elastase.

Amino Acid Sequence↗
PubMed1993

A sulphonylthiourea (BM 20) related to torasemide: a new loop diuretic with relative potassium-sparing properties.

A series of sulphonylthioureas related to torasemide, a high ceiling loop diuretic, were synthesized and found to inhibit the Na+ 2Cl- K+ co-transporter of the thick ascending limb of the loop of Henlé. Their diuretic properties were studied (30 mg kg-1) after oral administration to rats. Lipophilic derivatives, very active in-vitro, were found inactive orally and intraperitoneally in rats. The four most active compounds were examined for their dose-dependent diuresis. Three of them showed a potency, water and electrolyte excretion similar to torasemide. The fourth molecule, a sulphonylthiourea (BM 20), exhibited relative potassium-sparing properties and a minimal diuretic dose of 0.001 mg kg-1, 200 times lower than torasemide.

Administration, Oral↗
PubMed1993

First year experience using the Fischer ZD-Neurosurgical Localizing Unit with particular reference to the development of PET-guided stereotactic biopsy.

Initial experience using the Fischer ZD-Neurosurgical Localizing Unit is reviewed. During the first year, 26 stereotactic procedures were performed in 25 patients. Twenty-two patients underwent imaging-guided stereotactic biopsy. Among them, 20 were included in the protocol we have developed for combined positron emission tomography (PET)- and computerized tomography (CT)-guided stereotactic biopsy. The technique is briefly described and preliminary results are reported. Most low-grade tumors were found in hypometabolic/hypodense areas, glioblastomas were all diagnosed in areas with increased FDG uptake and contrast enhancement on CT while data for anaplastic astrocytomas were heterogeneous. Some of the biopsic trajectories performed in areas were there was no increased FDG uptake or in areas with increased FDG uptake but without contrast enhancement on CT were non diagnostic. This never occurred in areas with both increased FDG uptake and contrast enhancement. Other stereotactic procedures performed include 2 catheter placement for drainage of cystic lesions, 3 stereotactically guided open neurosurgical procedures and 1 third ventriculostomy. Procedural objectives were accomplished in all cases. From our experience, we found stereotactic procedures using this system safe, accurate, easy to handle and allowing a wide range of applications. Because the system is designed to be readily used in conjunction with modern planar imaging techniques (i.e. CT and magnetic resonance imaging), it allowed us to develop a technique for PET-guided biopsy which might increase the diagnostic yield of stereotactic biopsy of intracranial neoplasms.

Adolescent↗
PubMed1992

Na+,2Cl-,K+ cotransport system as a marker of antihypertensive activity of new torasemide derivatives.

A series of compounds related to torasemide, a loop diuretic, were synthesized and examined for their diuretic potency and inhibitory activity on the erythrocyte and renal medullary thick ascending limb vesicle Na+,2Cl-,K+ cotransport in Milan hypertensive (MHS) and normotensive (MNS) rat strains, where previous studies had demonstrated an alteration of the cotransport system genetically related to hypertension. From the results of the screening, structure-activity relationships were drawn and two compounds, JDL 961 and C 2921 were selected. Their IC50 on renal vesicle cotransport were similar in the two strains (JDL 961: MHS = 1.8 microM; MNS = 1.2 microM; C 2921: MHS = 4 microM; MNS = 3.8 microM), and were 4-8 times lower than those of torasemide (MHS = 13 microM; MNS = 31 microM, P less than 0.01) and 50-60 times lower than those of bumetanide (MHS = 145 microM; MNS = 206 microM, P less than 0.05) taken as reference compounds. Their ability to reduce the development rate of hypertension was tested both in MHS and in Okamoto spontaneously hypertensive rats (SHR) strain, in which cotransport alterations are opposite to those of MHS. Both torasemide derivatives (7.5 mg.kg-1 os per day) prevented development of hypertension in the two strains. The time course of this hypotensive activity was faster and the percentage of blood pressure fall greater in MHS (20-25%) than in SHR rats (12-15%), even though the absolute value of blood pressure fall was similar in MHS (JDL 961 = -17 mm Hg; C 2921 = -30 mm Hg) and SHR (JDL 961 = -25 mm Hg; C 2921 = -20 mm Hg). A superimposable effect of bumetanide was observed in the two strains, but at 8 times higher daily dose (60 mg.kg-1). These results suggest that new loop diuretics can be selected for their antihypertensive activity on the basis of their in vitro potency in inhibiting the Na+,2Cl-,K+.

Animals↗
PubMed1992

Design, synthesis and biological activity of a series of torasemide derivatives, potent blockers of the Na+ 2Cl- K+ co-transporter: in-vitro study.

Pharmacomodulation of the torasemide molecule, a loop diuretic inhibiting Na+ 2Cl- K+ co-transport in the thick ascending limb of the loop of Henlé has been performed in order to obtain new long-acting diuretics. The aim of this study was to decrease the metabolism of the drug and to slow down its rate of excretion by increasing its hydrophobicity. The present study describes the synthesis and the inhibitory potency of new torasemide derivatives in the bioassay system of the cortical thick ascending limb of rabbit. A correlation between the lipophilicity (log P') of these substances and their activity as inhibitors of the Na+ Cl- K+ co-transporter was observed. The present design led to compounds more active than torasemide. Structure-activity relationships permit us to propose an interaction model between torasemide derivatives and the Na+ 2Cl- K+ co-transport system of the cortical thick ascending limb.

Animals↗
PubMed1991

Three-quarter prone approach to the pineal-tentorial region. Report of seven cases.

We report our preliminary results (seven cases) with a three-quarter prone approach to the pineal-tentorial region using an opening beneath the midline. The technique we have used eliminates the risk of air embolism because the head is just over the right atrium, the table remaining in an horizontal plane. Using the natural effect of gravity, it is no more necessary to use retraction on the occipital lobe. So, hemianopsia is eliminated. We confirm the results of other teams who have used this approach which seems to us to be the best way to treat any lesion in the pineal-tentorial area.

Adult↗
PubMed1991

Sarcoidosis presenting as an isolated intramedullary tumor.

We report a case of isolated intramedullary sarcoidosis. The patient developed progressive signs that indicated a spinal tumor, which were investigated with contrast-enhanced magnetic resonance imaging scans. Magnetic resonance imaging clearly revealed an intramedullary lesion, but the diagnosis of sarcoidosis was made on the pathological analysis of the surgical specimen. Magnetic resonance imaging with contrast enhancement is reported in a histologically proven case of intramedullary sarcoidosis. Only 12 other cases of isolated intramedullary sarcoidosis have been reported. We review and discuss these cases according to their clinical presentation, the segmental location of the granulomas in the spinal cord, preoperative and operative diagnoses, and signs for systemic sarcoidosis. In none of the cases was the diagnosis of intramedullary sarcoidosis made before surgery. We think that surgical therapy for intramedullary lesions is the best way to diagnose rare instances of benign lesions like sarcoidosis and to treat them in an appropriate manner.

Contrast Media↗
PubMed1991

Antibacterial activity of 5-acylaminothiazole derivatives, synthetic drugs related to beta-lactam antibiotics.

Newly synthesized 5-acylaminothiazolium salts and one 5-acylaminothiazolidine, considering their chemical structure and reactivity, have been proposed as potential inhibitors of bacterial serine DD-peptidases. A moderate antibiotic activity with (5-phenylacetylamino-3-thiazolio)acetate and (5-phenylacetylaminothiazolidin-3-yl)acetic acid was observed on Staphylococcus aureus ATCC 25923. The methyl- and tert-butyl esters of the thiazolium salt have shown lower MIC values. Moreover, when introduced into an exponential growth phase culture of S. aureus, the three active thiazolium salts induced a partial lysis indicating an impairing of the bacterial cell wall biosynthesis. The observed time-dependent binding of the best compound to the PBPs of S. aureus was too slow and occurred at too high concentrations to account for its MIC value. Consequently, the antibiotic activity of the thiazolium salts on the S. aureus cells seems not to be satisfactorily explained by a penicillin-like interaction with the PBPs.

Anti-Bacterial Agents↗
PubMed1991

[Lesions of the pineal and tentorial region. Occipito-parietal approach in three-quarter prone position with infrasagittal craniotomy].

Surgical treatment of pineal-tentorial region lesions remains a challenge. The difficulty in approaching the pineal region can be verified with the number of operative plans that have been proposed to reach this area: transcallosal, occipital transtentorial, infratentorial supracerebellar approaches and sitting, prone or Concorde positions. This emphasizes the surgeon's dissatisfaction with the surgical techniques described. Recently, a three-quarter prone position with the bone flap placed under the midline has been described (1, 3, 8). We have decided to test this approach that we have slightly modified and we report our results on 13 cases: 2 arachnoid cysts, 3 vascular malformations and 8 tumors (3 brainstem gliomas, 2 dysgerminomas, 1 quadrigeminal plate metastasis and 1 meningioma plus 1 metastasis of the falx). Keeping the table in a horizontal plane, risks of air embolus are eliminated. Using the natural effect of gravity, traction on the occipital lobe is no more necessary and hemianopsia no more occurs. We recommand the parieto-occipital route which is the shortest way to reach epiphysis and falco-tentorial notch. We confirm the results of american colleagues (1, 3, 8, 15) and we advise to use this approach which seems to us the best way to treat pineal-tentorial lesions.

Adult↗
PubMedDate not supplied

Evaluation of classical NSAIDs and COX-2 selective inhibitors on purified ovine enzymes and human whole blood.

Cyclooxygenase is the key enzyme in the biosynthesis of prostanoids, biologically active substances involved in several physiological processes and also in pathological conditions such as inflammation. It has been well known for 10 years that this enzyme exists under two forms: a constitutive (COX-1) and an inducible form (COX-2). Both enzymes are sensitive to inhibition by conventional non-steroidal anti-inflammatory drugs (NSAIDs). Observations were made that COX-1 was mainly involved in homeostatic processes, while the COX-2 expression was associated with pathological conditions leading to the development of COX-2 selective inhibitors. Several methods have been reported for the evaluation of the COX-1 and COX-2 inhibitory potency and selectivity of conventional or COX-2 selective NSAIDs. In this study, we evaluated the COXs inhibitory profile of both conventional NSAIDs and COX-2 selective inhibitors using two different in vitro methods: the first test was performed using purified enzymes while the second method consisted of a whole blood assay. The results obtained with reference drugs in these two assays will be discussed and compared in this article.

Animals↗