Glucose and amino acid metabolism in chick telencephalon slices: Changes with incubation conditions and animals' development

Glucose and amino acid metabolism in 1- and 30-day-old chick telencephalon slices was studied in two incubation media in the presence or in the absence of a continuous oxygenation. Medium 1 has a composition and a tonicity similar to cerebrospinal fluid, medium 2 is hypertonic and does not contain any K⁺ ions. The incorporation of glucose carbon into amino acids and the distribution of radioactivity between the different amino acids are close to the ones observed in the chick brain in vivo only when the slices are incubated in medium 1, with oxygen at 30 days and without oxygen for the 1-day-old chick. It also appears that if oxygenation is necessary for incubation of mature brain tissue in vitro, the absence of the medium oxygenation is more suitable for the study of glucose metabolism in 1-day-old chick brain slices.     

Inspiratory flow rate and dead space in dogs

It is generally accepted that a stationary concentration front is established in the tracheobronchial tree during the inspiratory phase of single- and multiple-breath washouts. The anatomic position of this front, which is determined by the balance between diffusive flux toward the airway opening and convective flux toward the periphery, is frequently used to predict the effects of molecular diffusivity and inspiratory flow rate on dead space. Although there is substantial experimental evidence supporting the predictive effect of molecular diffusivity, there is little evidence regarding the effect of convective flow. This study confirmed the predictions for the effects of molecular diffusivity but contradicted those for the effects of inspiratory flow. We measured dead space by multiple- and single-breath inert gas washout techniques and also measured physiological dead space in dogs for inspiratory flow rates of 10-71 ml.kg-1.s-1. None of the three measures of dead space increased over the entire range of flow rate, as predicted by contemporary gas transport models. A possible explanation for these findings is that axial dispersion coefficients in the anatomic region where stationary fronts are believed to develop (respiratory bronchioles and alveolar ducts) significantly increase with convective flow rate rather than remain equal to molecular diffusivity.     

Production of specific antibodies to contractile proteins,and their use in immunofluorescence microscopy

Summary The injection of rabbits with insoluble or soluble G-actin from chicken smooth or striated muscle will produce antibodies that are equally reactive, and species and tissue non-specific in immunoprecipitation, immunofluorescence and actin-activated Mg²⁺-ATPase^** inhibition test. These antibodies have been used for the identification of actin-containing fibrils in a variety of tissues. When G-actins from chicken smooth or striated muscle are immobilized by chemical linkage to Affi-Gel 702 microbeads, their immunogenicity is increased, but the antibodies obtained against them are species-specific and will only react with actin and actin-containing structures from chicken and are therefore limited in use. It is concluded from this work that insoluble G-actin is the preferable immunogen to obtain precipitating antibodies for wide use.Abbreviations ATPase Adenosinetriphosphatase - FITC Fluoresceinisothiocyanate - SDS Sodiumdodecylsulfate This paper is dedicated to Dr. Dorothy M. Needham, University of Cambridge, England, in honour of her eightieth birthday     

α-methyl-6-aminodopamine: Depletion of catecholamines in mouse brain and peripheral tissues

A new synthetic agent R, S-2-amino-1(2-amino-4, 5-dihydroxyphenyl) propane dihydrobromide, also referred to as α-methyl-6-aminodopamine (α-Me-6-ADA), has been found to produce acute (one day) and longer-term (seven day) depletion of norepinephrine (NE) levels in mouse brain and peripheral tissues. A 100 mg/kg dose of α-Me-6-ADA (i.v., free base) produced greater than 85% depletion of NE in the heart and spleen at one day and one week after treatment. Intracranially, α-Me-6-ADA (100 μg i.vtr.) depleted NE in the telencephalon and brain stem by 79% and 21% respectively at seven days. In addition DA was depleted by 45% in the ipsilateral striatum. The α-Me-6-ADA appears to have a relative selectivity for noradrenergic nerves, as an intracranial dose of 10 μg, which decreased NE in mouse whole brain by 52% at one day, failed to alter the DA content. These data suggest that α-Me-6-ADA may be a neurotoxin.     

Tricyclic quinoxalines as ligands for the strychnine-insensitive glycine site

The synthesis of a series of tricyclic quinoxalines is described. These compounds exhibit good affinity for both the strychnine-insensitive glycine site of the NMDA receptor and the AMPA receptor.     

Low-temperature micronization of a peptide drug in fluid propellant: Case study cetrorelix

Aim of this study was to elaborate an efficient method for the micronization of the decapeptide cetrorelix (a GnRH-antagonist), in order to obtain a microsuspension as basis for other pharmaceutical preparations, such as e.g. inhalation aerosols. A modified pearl-mill coupled with a cryostat was used for the micronization of cetrorelix in fluid propellant and operated under different conditions. The obtained cetrorelix suspensions were analyzed for particle size distribution, purity of cetrorelix, and for metal contamination through abrasion from parts of the mill. The method allowed an effective micronization of cetrorelix. The mean particle size of the initial cetrorelix lyophilizate bulk ware was reduced from 52.5 μ (Volume Mean Diameter, VMD) down to 14.9, 6.1 and 3.1 μm, respectively, respectively. The HPLC analysis of all cetrorelix suspensions after micronization did not show signs of decomposition as compared to the initial product. The elementary analysis of the suspensions performed by inductively coupled plasma mass spectrometry revealed a negligible amount of contaminants in the suspension (Zr=max. 0.6 ppm; Fe, Cr, Ni, Ba, below limit of quantification, i.e.<0.14 ppm). The only appreciable contaminant. Aluminum (Al=1.1 ppm), was derived from the mechanical capping of aluminum canisters prior to analysis. The Zr determination in the suspension of 0.6 ppm, is still considered to be negligible as compared to the legally tolerated limit of air contamination. By low-temperature micronization in fluid propellant, fine drug suspensions of cetrorelix for pMDIs can be directly manufactured in one-step procedure without destruction of the peptide structure and without appreciable product contamination. Published: July 12, 2001.     

Beta(1)/beta(2)/beta(3)-adrenoceptor knockout mice are obese and cold-sensitive but have normal lipolytic responses to fasting

Catecholamines are viewed as major stimulants of diet- and cold-induced thermogenesis and of fasting-induced lipolysis, through the β-adrenoceptors (β₁/β₂/β₃). To test this hypothesis, we generated β₁/β₂/β₃-adrenoceptor triple knockout (TKO) mice and compared them to wild type animals. TKO mice exhibited normophagic obesity and cold-intolerance. Their brown fat had impaired morphology and lacked responses to cold of uncoupling protein-1 expression. In contrast, TKO mice had higher circulating levels of free fatty acids and glycerol at basal and fasted states, suggesting enhanced lipolysis. Hence, β-adrenergic signalling is essential for the resistance to obesity and cold, but not for the lipolytic response to fasting.