Mechanics of an Asymmetric Hard-Soft Lamellar Nanomaterial.

Nanolayered lamellae are common structures in nanoscience and nanotechnology, but most are nearly symmetric in layer thickness. Here, we report on the structure and mechanics of highly asymmetric and thermodynamically stable soft-hard lamellar structures self-assembled from optimally designed PS1-(PI-b-PS2)3 miktoarm star block copolymers. The remarkable mechanical properties of these strong and ductile PS (polystyrene)-based nanomaterials can be tuned over a broad range by varying the hard layer thickness while maintaining the soft layer thickness constant at 13 nm.

Differential germ cell proliferation in the salamander pleurodeles waltl: controls by sexual genotype and by thermal epigenetic factor before differentiation of sexual phenotype of gonads.

In the acceptance that, during early gonadogenesis, variations of germ cell (GC) proliferation express interactions between germ and somatic cells, early events occurring before histological differentiation of gonadal sex has been detected and timed through GC counts on larvae of Pleurodeles waltl (urodele amphibia) issued from male ZZ or female ZW monosexual offspring. Gonads differentiate in accordance with sexual genotype in ZZ and ZW larvae at room temperature and in ZZ larvae at 32 degrees C whereas they are sex-reversed at 32 degrees C in ZW larvae, becoming phenotypic neomales. At both the rearing temperatures, in genital ridges, GCs do not proliferate during a period called P0 period ending earlier in ZZ than in ZW larvae.

Primordial germ cell proliferation in the salamander Pleurodeles waltl: genetic control before gonadal differentiation.

PGC counts were carried out on larvae of Pleurodeles waltl (urodele amphibia) issued from standard, monosexual male and monosexual female offspring while the genital ridges were settling. During this period, which is characterized by a zero mitotic index (and is therefore called the Po period), and which lasts from stage 35 to stage 41, no PGC proliferation occurs. A statistical analysis indicated that PGC counts per larva are sex genotype independent and that offspring may be divided into three groups with average PGC counts of 96.

Catecholamine sulfates: end products or metabolic intermediates?

Dopamine-beta-hydroxylase catalyzes the beta-oxidation of dopamine to noradrenaline while phenylethanolamine-N-methyltransferase converts noradrenaline to adrenaline. Since catecholamine sulfates represent the predominant form of catecholamines in human tissues, we have studied the role of dopamine sulfate and noradrenaline sulfate as alternate substrates for dopamine-beta-hydroxylase and phenylethanolamine-N-methyltransferase, respectively. Dopamine 3-sulfate, dopamine 4-sulfate and noradrenaline 3-sulfate were chemically synthesized and exhaustively purified by ion-exchange chromatography.

The activity of human kidney arylsulfatases A and B towards catecholamine sulfates.

Both arylsulfatases (EC 3.1.6.

Is the platelet phenolsulfotransferase involved in the sulfoconjugation of plasma catecholamines?

Catecholamines are predominantly present in the sulfoconjugated forms in human plasma. Phenolsulfotransferase (EC 2.8.

Turnover of free and conjugated serum catecholamines during hemodialysis.

The response of the catecholaminergic system was evaluated in uremic patients maintained on a chronic outpatient hemodialysis (HD) program. Serum concns of free and conjugated catecholamines (CA) were measured prior to and following HD and in response to upright posture, and were compared to values obtained in a normal group of individuals submitted to the same stimuli. Before HD, the level of free plasma dopamine (DA) (155 +/- 58 pg ml-1) was comparable to that of normal individuals (38 +/- 12 pg ml-1) due to the large number of individuals of the 2 groups having undetectable serum levels.

Determination of free and conjugated catecholamines and L-3,4-dihydroxyphenylalanine in plasma and urine: evidence for a catechol-O-methyltransferase inhibitor in uraemia.

A sensitive, accurate and reproducible method has been developed for the determination of free and conjugated catecholamines and L-3,4-dihydroxyphenylalanine in plasma and urine. The assay involves the enzymatic conversion of these compounds to their radio-labelled O-methylated derivatives using catechol-O-methyltransferase and S-adenosyl-L-[methyl-(3)H]methionine. Recoveries of 75 + /- 5% for dopamine, 70 + /- 5% for adrenaline and 65 + /- 5% for noradrenaline were obtained.

[Spinal cord compression by extramedullary hematopoiesis in chronic eosinophilic leukemia (author's transl)].

A progressive paraplegia appeared in a 54 years old patient during a chronic eosinophilic leukemia. Myelography revealed a block of the spinal canal at T3. Laminectomy discovered an extramedullary hematopoiesis in the epidural space.

Tonin--angiotensin II system in hypertension.

1. A single intravenous administration of rabbit tonin antiserum into one-kidney one-clip hypertensive rats restored blood pressure to normal in seven out of ten animals. There was little change in blood pressure in two-kidney one-clip hypertensive, uninephrectomized or sham-operated rats.

N-Terminal amino acid sequence of rat tonin: homology with serine proteases.

In this paper, we present the amino-terminal sequence of rat tonin, an endopeptidase responsible for the conversion of angiotensinogen, the tetradecapeptide renin substrate, or angiotensin I to angiotensin II. It is shown that isoleucine and proline occupy the amino- and carboxy-terminal residues respectively. The N-terminal sequence analysis permitted the identification of 34 out of the first 40 residues of the single polypeptide chain composed of 272 amino acids.

A direct radioimmunoassay for tonin.

A sensitive radioimmunoassay for the measurement of tonin is described. It is based on the use of antibodies produced in rabbits against highly purified tonin obtained from rat submaxillary gland. A radioiodinated enzyme with high specific activity was obtained by the chloramine-T method.

Effect of antitonin on blood pressure in the one-kidney hypertensive rat.

1. The tonin concentration of saliva and submaxillary glands was studied in one-clip hypertensive rats with or without the contralateral kidney. 2.

[The neurosecretory cells of the cerebral ganglia and the nerve chain in the isopod crustacean Asellus aquaticus L. Cyclic variations in the beta type cells as a function of reproduction].

Asellus aquaticus L. cerebral ganglions and nervous cord contain seven types of neurosecretory cells; two of these are similar to Malacostraca beta and alpha cells. Female beta cells are the seat of cyclic acidophil variations which are connected to ovocyte growing; this acidophil secretion is superimposed on the basophil constant secretion in male and female beta pericaryons.

Substrate specificity of tonin from rat submaxillary gland.

The substrate specificity of tonin from rat submaxillary gland was examined with a series of synthetic peptides encompassing the C-terminus of the decapeptide substrate angiotensin I. In contrast to angiotensin I-converting enzyme from plasma or lung, only angiotensin I, (des-Asp1)-angiotensin I, and (des-Asp1, des-Arg2)-angiotensin I are substrates of tonin with Km values of 34.5 muM, 39.