Involvement of a large inverted repeated sequence

Summary Southern hybridization of the total DNA of Agrocybe aegerita with cloned mitochondrial (mt) probes revealed a sequence homology between two distant mitochondrial restriction fragments. From the mtDNA restriction map and the distribution of restriction sites on the cross-hybridizing mitochondrial fragments, two copies of a large inverted repeated sequence (IR) of 3 kbp were located on the mitochondrial genome. These IR sequences divided the 80 kbp mtDNA into two singlecopy regions of 24 kbp (SSC) and 50 kbp (LSC). For the first time in higher fungi, this IR sequence has been shown to be involved in an intramolecular homologous recombinational event. Such a rearrangement led to an inversion of the orientation of the two unique-copy regions, without any change in mtDNA complexity. The location of the recombinational event was compared with previously reported plant and fungal mitochondrial rearrangements and the potential role of the IR sequence was discussed.     

Flexibility of scoliosis. What does it mean? Is this terminology appropriate?

This work is a critical analysis of the term "flexibility of scoliosis." The authors demonstrate that this measure includes two very different and noncorrelated phenomena: the collapse and the reducibility of the structural curve. In 228 paralytic curves, these two phenomena were quantified and correlated with different parameters of scoliosis: sex, stage of maturation, curve pattern, number of vertebrae in the curve, spinal and abdominal test values, and the scoliotic evolution rate. Reducibility can be predicted since it is an elasticity process. Collapse is more complex, but it is a prognostic factor for evolution and effectiveness of treatment. The preliminary results of a similar study of idiopathic scoliosis are the same.     

Alpha-1 and alpha-2 adrenoceptor binding in cerebral cortex: Competition studies with [3H]prazosin and [3H]idazoxan

Summary The tritiated adrenergic antagonists prazosin ([³H]PRZ) and idazoxan ([³H]IDA, or RX-781094) bind specifically and with high affinity in membrane preparations from cerebral cortex to alpha-1- and alpha-2-adrenoceptors respectively. Saturation experiments, performed to determine the density of receptors (B_max; maximum binding capacity) and the dissociation constant (K_d 25 °C), were analyzed by the methods of Eadie and Hofstee, iterative modelling, and the procedure of Hill. The pharmacologic properties and specificity of the labelling was verified by displacement experiments using alpha-adrenergic antagonists and agonists. The antagonist drugs showed the following order of potency to displace [³H]prazosin: prazosin phentolamine corynanthine > pyrextramine yohimbine piperoxan > benextramine > idazoxan; for the agonists: clonidine (–)-noradrenaline (–)-adrenaline phenylephrine, while other drugs, such as (–)-propranolol, dopamine, (–)-isoproterenol and serotonin only competed with the alpha-1-ligand at concentrations above 20 M. The alpha₂-sites labelled by [³H]idazoxan were characterized by the antagonist displacement sequence idazoxan phentolamine > yohimbine = > piperoxan pyrextramine benextramine prazosin corynanthine. The agonists order of potency to compete with [³H]idazoxan was clonidine phenylephrine = > (–)-adrenaline > (–)-noradrenaline, and for other related drugs it was (–)-propranolol dopamine serotonin > (–)-isoproterenol. These competition experiments clearly showed two pharmacologically distinct sites, but question the relative specificity of some of the adrenergic drugs.Abreviations [³H]PRZ [³H]prazosin - [³H]IDA [³H]idazoxan - B_max maximum binding capacity - K_d dissociation constant - IC 50 inhibitory concentration that reduces binding by 50% - K_i inhibition-dissociation constant - nH Hill coefficient - CMC coefficient of multiple correlation - fmol/mg p fentomoles per mg of protein - nM nanomolar Recipient of a F.R.S.Q. Studentship.     

The popliteal entrapment syndrome

Summary Five examples of the popliteal entrapment syndrome have been reported in 4 patients aged between 17 and 41. The diagnosis in each case was made pre-operatively. The anatomical anomalies consisted in three instances of an abnormally high insertion of the inner gemellus (medial head of gastrocnemius) muscle tendon with the artery located twice in front and once in the middle of the tendon, in another instance compression was due to a hypertrophic musculus plantaris and finally, in the last instance, the anomalies were caused by abnormal fibrous bands. In two instances the artery was thrombosed, in three it was compressed in an intermittent fashion. The patients responded well to treatment, by a graft in the case of thrombosis, and by sectioning the abnormal insertions of the gemellus muscle or the fibrous bands in the others. The frequency of these different anatomical types, the relative evolutivity and the embryological hypotheses are studied in the 111 cases recorded in the literature between 1970 and 1983.

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Le piège poplité

Résumé Cinq cas de poplitées piégées sont rapportés chez 4 patients dont l'âge était compris entre 17 et 41 ans. Le diagnostic a été fait dans chaque cas en pré-opératoire. Les anomalies anatomiques consistaient trois fois en une insertion anormalement haute du tendon du jumeau interne, l'artère siégeant 2 fois en avant et 1 fois au milieu du tendon, dans un cas en une compression par un muscle plantaire grêle hypertrophique, enfin dans le dernier cas, il s'agissait de bandes fibreuses anormales. Dans 2 cas, l'artère était thrombosée, dans 3 cas, elle était comprimée de façon intermittente. Les patients ont été traités avec succès par pontage en cas de thrombose, et par section des insertions anormales du jumeau interne ou des bandes fibreuses dans les autres cas. La fréquence des différents types anatomiques, l'évolutivité relative, et les hypothèses embryogénétiques sont étudiées à partir de 111 autres cas rapportés dans la littérature entre 1970 et 1983.

     

Hypersensitivity of the corticotropic axis to the serotoninergic agent clomipramine in obese women

Serotoninergic control of food intake has been shown to be abnormal in obese persons with a decrease in serotoninergic tone. The neuroendocrine effects of intravenous I.V. administration of clomipramine (CMI), a serotonin uptake inhibitor, were studied in normal-weight (n=7) and obese subjects before (n=12) and after (n=6) dietary restriction. Under double-blind, placebo-controlled conditions, a single 12.5 mg dose of CMI was administered. There was no difference in baseline values of prolactin (PRL), corticotropin (ACTH) and cortisol in non-obese controls, obese before and obese after weight loss. CMI led to significant increases of PRL, ACTH, and cortisol concentrations in the controls as well as the obese group. The ACTH and cortisol responses to CMI in obese subjects were somewhat greater than the responses in normal-weight subjects. The area under the curve AUC for ACTH after clomipramine was 6202 +/- 976 pg/ml x 150 minutes for tile obese before weight loss and 3274 +/- 512 pg/ml x 150 minutes for the controls and the difference was significant at the level of p=0.052. The cortisol peak value after clomipramine was 163.71 +/- 14.31 ng/ml in the non-obese and 214.66 +/- 12.59 ng/ml in the obese (p=0.025). However, there was no difference in the obese subjects before and after weight loss. These data support the assumption that obese women have an abnormal sensitivity to the serotoninergic control of the hypothalamic pituitary adrenal axis (HPA), and that a mild weight loss does not significantly modify their serotoninergic tone.     

Net postprandial utilization of [15N]-labeled milk protein nitrogen is influenced by diet composition in humans

The aim of this study was to follow the fate of dietary nitrogen to assess the postprandial utilization of purified milk protein and to determine the acute influence of energy nutrients. For this purpose, a [15N]-labeling dietary protein approach was used. Twenty-five subjects swallowed an ileal tube and ingested [15 N]-milk protein alone or supplemented with either milk fat or sucrose. The absorption and postprandial deamination of dietary protein was monitored for 8 h. Sucrose delayed the absorption of protein longer than fat, but the ileal digestibility did not differ among groups (94.5-94.8%). Sucrose, but not fat, significantly reduced the postprandial transfer of [15N]-milk nitrogen to urea. Consequently, the net postprandial protein utilization (NPPU) of milk protein calculated 8 h after meal ingestion was 80% when ingested either alone or supplemented with fat and was significantly greater with sucrose (NPPU = 85%). This study shows that energy nutrients do not affect the nitrogen absorption but modify the metabolic utilization of dietary protein in the phase of nitrogen gain. Our method provides information concerning the deamination kinetics of dietary amino acids and further allows the detection of differences of dietary protein utilization in acute conditions. The diet composition should be carefully considered, and protein quality must be determined under optimal conditions of utilization.     

Oxidant stress: the role of nutrients in cell-lipoprotein interactions

Oxidant stress is increasingly becoming an important hypothesis to explain the genesis of several pathologies, including cancer, atherosclerosis and also ageing. Beside a few rare genetic defects, dietary factors are thought to play a key role in the regulation of the production of reactive oxygenated species. An imbalance between nutrients, and in particular those involved in antioxidant status, could explain the onset of an enhanced production of free radicals. We will briefly review information concerning oxidation of lipids and lipoproteins which lead to atherothrombosis. We also present new findings supporting a role for blood platelets in generating oxidant species. New data are also described concerning the role of oxygenated derivatives of cholesterol, oxysterols, in cellular cholesterol efflux and NO production. Also, new developments relating to the influence of direct effects of free radicals on cellular cholesterol homeostasis are presented. Finally, the in vitro effects of butyrate, a natural short-chain fatty acid produced by bacterial fermentation, in the protection against free radical-mediated cytotoxicity are discussed. These data provide information on the mechanisms of dietary antioxidants in preventing oxidant stress.