The pharmacological properties of the imidazobenzodiazepine, FG 8205, a novel partial agonist at the benzodiazepine receptor

1. The pharmacological properties of the benzodiazepine receptor ligand, FG 8205 (7-chloro-5,6-dihydro-5-methyl-6-oxo-3-(5-isopropyl-1,2,4-oxadiazol++ +-3-yl)-4H- imidazol[1,5a][1,4]benzodiazepine) have been examined. 2. FG 8205 potently displaced [3H]-flumazenil binding in rat cortical membranes with a Ki of 3.3 nM, but was inactive at 13 neurotransmitter recognition sites. 3. Consistent with a partial agonist profile, the affinity of FG 8205 for the benzodiazepine recognition site was increased in the presence of gamma-aminobutyric acid (GABA, 300 microM) by a degree (-log [IC50 in the presence of GABA/IC50 alone] = 0.34) significantly less than found for diazepam (0.46). FG 8205 also potentiated the inhibitory potency of the GABAA-receptor agonist, isoguvacine, on the hippocampal CA1 population spike and, again, the maximum shift (-log dose-ratio = 0.2) was significantly less than that seen with diazepam (0.4). 4. In anticonvulsant studies, the ED50 doses of FG 8205 and diazepam needed to antagonize seizures induced by pentylenetetrazol (PTZ) or by sound in audiogenic seizure prone mice were similar with values of 0.2-0.3 mg kg-1, i.p. However, even high doses of FG 8205 (50 mg kg-1) did not protect against seizures induced by electroshock. 5. FG 8205 released responding suppressed by footshock in a rat operant conditioned emotional response task over the dose range 0.5-50 mg kg-1 (i.p.). Similar doses of FG 8205 had a marked taming effect in cynomolgus monkeys.(ABSTRACT TRUNCATED AT 250 WORDS)     

Angiographic and histologic findings in high frequency rotational ablation in coronary arteries in vitro

High-frequency rotational angioplasty is a recently developed method for coronary angioplasty in the catheter laboratory. An elliptical burr tip (phi 1.25-2.0 mm) with embedded diamant chips (phi 40-50 microns) is rotated by a helical drive shaft at 150,000-180,000 rpm. The burr is advanced over a 0.009-inch coaxial guide wire. To show the effects of this approach in diseased and healthy vessels, which may be present before and behind a stenosis, 17 atherosclerotic coronary arteries of nine human hearts, and 18 normal coronary arteries of nine pig hearts were treated by this method in vitro. Standardized coronary angiography was performed before and after Rotablator treatment, followed by histological examination. From these data the burr-to-vessel-diameter ratio was calculated for each vessel segment and compared with the angiographical and histological outcome. Partial or complete removal of the circumference of the innermost vessel wall layers was observed regularly. The average removal of tissue in human coronary arteries was limited to the intimal layer and in the pig coronary arteries to the internal elastic membrane. In the pig coronary arteries no intimal tears or dissections occurred, in human coronary arteries tears could be seen frequently (13 of 17 vessels (76%)). Media tears were observed in 3 of 17 vessels; one (2%) media dissection could be demonstrated; no perforation occurred. Thus, the in vitro studies suggest that coronary rotational angioplasty has only a slight effect on the vessel segment next to a stenosis, regardless of the burr-to-vessel-diameter ratio.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vectorization of morpholino oligomers by the (R-Ahx-R)4 peptide allows efficient splicing correction in the absence of endosomolytic agents.

The efficient and non-toxic nuclear delivery of steric-block oligonucleotides (ON) is a prerequisite for therapeutic strategies involving splice correction or exon skipping. Cationic cell penetrating peptides (CPPs) have given rise to much interest for the intracellular delivery of biomolecules, but their efficiency in promoting cytoplasmic or nuclear delivery of oligonucleotides has been hampered by endocytic sequestration and subsequent degradation of most internalized material in endocytic compartments. In the present study, we compared the splice correction activity of three different CPPs conjugated to PMO(705), a steric-block ON targeted against the mutated splicing site of human beta-globin pre-mRNA in the HeLa pLuc705 splice correction model. In contrast to Tat48-60 (Tat) and oligoarginine (R(9)F(2)) PMO(705) conjugates, the 6-aminohexanoic-spaced oligoarginine (R-Ahx-R)(4)-PMO(705) conjugate was able to promote an efficient splice correction in the absence of endosomolytic agents. Our mechanistic investigations about its uptake mechanisms lead to the conclusion that these three vectors are internalized using the same endocytic route involving proteoglycans, but that the (R-Ahx-R)(4)-PMO(705) conjugate has the unique ability to escape from lysosomial fate and to access to the nuclear compartment. This vector, which has displays an extremely low cytotoxicity, the ability to function without chloroquine adjunction and in the presence of serum proteins. It thus offers a promising lead for the development of vectors able to enhance the delivery of therapeutic steric-block ON in clinically relevant models.     

Dystonia induced by combined treatment with L-dopa and MK-801 in parkinsonian monkeys.

We examined whether the N-methyl-D-aspartate antagonist MK-801 (dizocilpine) would reverse parkinsonism or potentiate the effects of L-dopa in primates treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In contrast to its effect in rodent models, treatment with MK-801 (0.1 mg/kg) caused bradykinesia and ataxia in parkinsonian primates, but no locomotor stimulation. Coadministration of MK-801 (0.1 mg/kg) with L-dopa (20 mg/kg) induced marked dystonia accompanied by bradykinesia and ataxia. Dystonia was not induced by either treatment given alone. These findings indicate that MK-801 should not be advocated as an adjunct to dopamine agonist therapy in Parkinson's disease.     

Dose-dependent headache response and dilatation of limb and extracranial arteries after three doses of 5-isosorbide-mononitrate

Summary The aim of the present study was to compare the ability of different doses of isosorbide-5-mononitrate (5-ISMN) to cause dilatation of medium sized and small arteries, and to examine the intensity and duration of any headache produced. Ten healthy volunteers each received 3 doses of 5-ISMN and placebo on separate days. The diameters of the radial and superficial temporal arteries were repeatedly measured with high frequency ultrasound and pain was scored using a 10 point verbal scale.A clear dose-relationship was found for plasma concentrations and headache, and for changes in the diameter of the temporal artery, but not for the radial artery.It is concluded that headache after 5-ISMN is caused by arterial dilatation or by mechanisms responsible for the arterial dilatation. Ultrasound monitoring of arterial diameters is an important and sensitive tool in the evaluation of nitrates and other vasodilators.     

Influence of caseload and surgical speciality on outcome following surgery for colorectal cancer: a review of evidence. Part 1: short-term outcome

OBJECTIVE: An association between caseload and outcome has been reported for complex surgical procedures. We systematically reviewed recent literature to determine whether caseload and surgical speciality are associated with short-term outcome following colorectal cancer surgery. METHOD: We searched the MEDLINE and Cochrane Library databases for relevant publications starting in 1992. We selected hospital caseload and type, and surgeon's caseload, education and experience as variables of interest. Measures of outcome were postoperative morbidity, in-hospital and 30-day mortality, and for rectal cancer anastomotic leak. We stratified the 35 reviewed studies by tumor location: colonic cancer, rectal cancer, or colorectal cancer and described the studies individually. A meta-analysis was performed only when it was considered appropriate. RESULTS: For colonic cancer, postoperative morbidity was associated with surgeon's caseload and education. Postoperative mortality was strongly associated with hospital caseload (OR 0.64, 95% CI 0.55-0.73), and surgeon's caseload (OR 0.50, 95% CI 0.39-0.64). It was also influenced by surgeon's education and experience. For rectal cancer, we found no evidence of an association between the selected variables and short-term outcome, including frequency of anastomotic leak. For colorectal cancer, there was evidence for an association between postoperative morbidity and hospital caseload. CONCLUSION: Our review offers evidence for a positive association between high hospital caseload, surgeon's caseload, sub-speciality and experience and improved short-term outcome in colonic cancer surgery. We failed to find evidence of a relationship for rectal cancer surgery, possibly owing to methodological artifacts. No study reported an inverse relation.     

Sequestration patterns of transfused rat neutrophilic granulocytes under normal and inflammatory conditions

Abstract: The fate of polymorphonuclear neutrophilic granulocytes (PMN) after their mobilization from the bone marrow of healthy individuals is not clearly understood. It has been suggested that there is a continuous utilization of these cells in widespread, subclinical inflammatory foci, where they are ultimately degraded. The goal of the present experiments was to determine whether an alternative ecotaxis (“homing”) exists, namely sequestration and degradation of PMN by mononuclear phagocytes exposed to the bloodstream in the liver, spleen and bone marrow. Blood PMN were collected from donor rats, labelled with ⁵¹Cr, and injected i.v. into 2 syngeneic rats, one of them having an induced sterile peritonitis. After various time intervals up to 18 h, the rats were killed and exsanguinated. As expected, we found cell-bound radioactivity in the inflamed peritoneal cavities, and also a high amount of radioactivity in liver, spleen, and bone marrow. The bone marrow uptake of PMN appeared to be much lower in the inflammation rats than in the normal controls. These findings were confirmed in PMN transfer experiments using PVG rats congenic for the RT7 alloantigenic system. Here, transfused blood leukocytes were traced with fluorescent, monoclonal HIS41 antibodies and flow cytometry. A possible corticosteroid effect on the bone marrow sequestration could not be substantiated. Uptake and degradation of PMN takes place in organs containing phagocytes exposed to the bloodstream. Sequestration of PMN in the bone marrow is apparently down-regulated in inflammatory states, perhaps increasing the PMN availability to inflamed tissue.     

Acute phase reaction, heterogeneity, and microheterogeneity of serum proteins as nonspecific tumor markers in lung cancer

The acute phase proteins, orosomucoid, ceruloplasmin, antitrypsin, and haptoglobin were measured in serum from 54 patients with lung cancer, 16 patients with benign lung inflammation, and 30 healthy individuals. A statistical correlation was found between tumor size and acute phase protein level, which, however, was ascribed to nonspecific inflammation in the tissues surrounding the tumor. The patients who subsequently could not be radically treated by surgery had higher concentrations of orosomucoid and ceruloplasmin than the radically treated patients. No difference in acute phase protein concentration was found between benign and malignant disease. The glycan-dependent microheterogeneity of orosomucoid and ceruloplasmin was analyzed by crossed affinoimmunoelectrophoresis with lectins, and the patterns of the patients with benign inflammation and malignant disease were different. The heterogeneity of ceruloplasmin was also analyzed by crossed immunoelectrophoresis without lectin. This analysis, combined with the total serum concentration of ceruloplasmin, made it possible to discriminate the 54 cases of malignancy from the 46 cases of nonmalignancy with a sensitivity of 78% and a specificity of 93%. It is suggested that the simple electrophoretic analyses of (micro-)heterogeneity is a valuable supplement to the acute phase profile in isolating high-risk patients and in monitoring radically treated cancer patients for relapse.