The Circadian Rhythm of Plasma Thyrotropin in Depression and Recovery

The 24-hr patterns of plasma thyrotropin have been observed in 12 endogenous depressed patients in both depressed and recovered states and in 13 normal subjects. A clear circadian rhythm was detected in controls with high values at night. In depression, the circadian rhythm was altered with amplitude reduction and blunted nocturnal secretion, abnormalities particularly relevant in bipolar patients. This flattened profile could be linked to the blunted response of TSH to TRH administration reported in depressed patients. Normal nyctohemeral patterns have been restored after recovery. These chronobiological abnormalities as well as their normalization under antidepressant drugs seem to be similar to those reported for various parameters (e.g. temperature, Cortisol, etc) in depression which could support the chronobiological hypothesis for affective disorders.     

Analysis of brain and myelin lipids by high-performance thin layer chromatography and densitometry

We have developed a simple method involving high-performance thin layer chromatographic separation of total brain and myelin lipids. Only two solvent systems consisting of chloroform: methanol: acetic acid and water at different concentrations were needed. The plate was then stained with three sequential procedures to visualize phospholipids, cholesterol and galactolipids. Densitometric procedure at each step of staining was utilized to obtain quantitative analysis of brain and myelin samples.     

Origin heterogeneity of Hb Lepore-Boston gene in Italy

Forty-three hybrid delta-beta-globin genes were characterized by DNA sequence analysis and associated RFLP haplotypes in 40 families from Abruzzo and Campania, which are on the east and west coast of Italy, respectively. All the genes had the delta-globin sequence up to the exon 2 codon 87 and had the beta-globin sequence from IVS-2-8; between these two ends, they had 58 bp in common with the delta- and beta-globin genes. Thus, they were all of the Lepore-Boston type. A chromosomal background heterogeneity was present among the mutant genes. In fact, they were all associated with (+ - - - -) 5' subhaplotype, but 23/31 from Campania were associated with (+ +) 3' subhaplotype, whereas 12/12 genes from Abruzzo and 8/31 from Campania were associated with (+ -). DNA sequencing of homozygous subjects showed that (+ +) 3' subhaplotype was associated, at IVS-2-74, with G, while (+ -) was associated with T; that is they were associated with the beta-globin gene sequence of frameworks 1 and 2, respectively. The molecular characteristics of this heterogeneity, as well as its geographical patterns in the eastern and western regions of Italy, represent strong evidence for the recurrent and multicentric origins of the mutation.     

Effect of propylthiouracil-induced hypothyroidism on cerebral cortex of young and aged rats: Lipid composition of synaptosomes,muscarinic receptor sites,and acetylcholinesterase activity

The effect of hypothyroidism on the lipid composition of synaptosomes, density and affinity of muscarinic receptor sites, and acetylcholinesterase activity in the cerebral cortex of young and aged rats was investigated. The animals were made hypothyroid by adding 0.05% propyl-2-thiouracil to their drinking water for four weeks. This pathological state induced an increase in the relative percentage of sphingomyelin in young rats. In aged rats hypothyroidism induced a decrease of sphingomyelin and glycerophosphocholine and an increase of cholesterol. The effect of hypothyroid state on cerebral cortex resulted in an increase of acethylcholinesterase activity both in young and aged rats and was also reflected in an increase of density of M1-AChRs but only in the former.     

Evolution of the ATP-binding-cassette transmembrane transporters of vertebrates

The ATP-binding-cassette transmembrane transporters (ABC transporters) known from vertebrates belong to four major subfamilies: (1) the P- glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance regulators (CFTR); (3) the Tap proteins encoded with the major histocompatibility complex of mammals; and (4) the peroxisomal membrane proteins. Both Pgp and CFTR have a structure suggesting a past internal gene duplication; a phylogenetic analysis indicated that these duplications occurred independently, while an independent tandem gene duplication occurred in the case of the Tap family. Both the Pgp and Tap proteins show evidence of relationship to bacterial ABC transporters lacking internal duplication, and both are significantly more closely related to the HlyB and MsbA families of transporters from purple bacteria than they are to ABC transporters from nonpurple bacteria. The simplest hypothesis to explain this observation is that eukaryotic Pgp and Tap genes are descended from a mitochondrial gene or genes that were subsequently translocated to the nuclear genome. The Pgp genes of eukaryotes are characterized by a remarkable degree of convergent evolution between the ATP-binding cassettes of their N- terminal and C-terminal halves, whereas no such convergence is seen between the two halves of CFTR genes or between the duplicated Tap genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain not found in other ABC transporters apart from CFTR, showed high levels of both synonymous and nonsynonymous difference in comparisons among different mammalian species, suggesting that this region is a mutational hot spot.      

Evidence for the presence of β-lactamase inStreptomyces glaucescens and its inhibition by sodium clavulanate

Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis.     

Two distinct and independent sites on IL-6 trigger gp 130 dimer formation and signalling.

The helical cytokine interleukin (IL) 6 and its specific binding subunit IL-6R alpha form a 1:1 complex which, by promoting homodimerization of the signalling subunit gp130 on the surface of target cells, triggers intracellular responses. We expressed differently tagged forms of gp130 and used them in solution-phase binding assays to show that the soluble extracellular domains of gp130 undergo dimerization in the absence of membranes. In vitro receptor assembly reactions were also performed in the presence of two sets of IL-6 variants carrying amino acid substitutions in two distinct areas of the cytokine surface (site 2, comprising exposed residues in the A and C helices, and site 3, in the terminal part of the CD loop). The binding affinity to IL-6R alpha of these variants is normal but their biological activity is poor or absent. We demonstrate here that both the site 2 and site 3 IL-6 variants complexed with IL-6R alpha bind a single gp130 molecule but are unable to dimerize it, whereas the combined site 2/3 variants lose the ability to interact with gp130. The binding properties of these variants in vitro, and the result of using a neutralizing monoclonal antibody directed against site 3, lead to the conclusion that gp130 dimer is formed through direct binding at two independent and differently oriented sites on IL-6. Immunoprecipitation experiments further reveal that the fully assembled receptor complex is composed of two IL-6, two IL-6R alpha and two gp130 molecules. We propose here a model representing the IL-6 receptor complex as hexameric, which might be common to other helical cytokines.     

Investigation of the vascular actions of arachidonate lipoxygenase and cyclo-oxygenase products on the isolated perfused stomach of rat and rabbit

The vascular actions of several prostanoids and arachidonate lipoxygenase products were investigated on the gastric circulation of rat and rabbit perfused with Kreb's solution. Under resting conditions, prostacyclin and PGE₂ produced small decreases in perfusion pressure with prostacyclin being the more potent. During vasoconstriction induced by infusion of noradrenaline, vasopressin or angiotensin II, prostacyclin was 20–40 times as active as PGE₂ as a gastric vasodilator in rat or rabbit stomach. PGF_2α was a less potent vasoconstrictor than noradrenaline, while the epoxy-methano endoperoxide analogue produced a long-lasting vasoconstriction. The putative metabolite, 6-oxo-PGE₁ was less active than prostacyclin as a vasodilator, having comparable activity to PGE₁, whereas 6-oxo-PGF_1α had very little activity. The endoperoxide, PGH₂ reduced perfusion pressure, this effect being inhibited by concurrent infusion of 15-HPETE. The vasodilation induced by arachidonic acid was likewise reduced by 15-HPETE, and abolished by indomethacin infusion. The arachidonate lipoxygenase hydroperoxides were vasodilator in the gastric circulation, the rank order of potency being 12-HPETE > 11-HPETE > 5-HPETE > 15-HPETE in both rat and rabbit stomach. It is possible that such vasoactive lipoxygenase products, may play modulator roles in the gastric mucosa.     

Three-Dimensional Trabecular Alignment Model

The Shear-slip Mesh Update Method (SSMUM) is being used in flow simulations involving large but regular displacements of one or more boundaries of the computational domain. We follow up the earlier discussion of the method with notes on practical implementation aspects. In order to establish a benchmark problem for this class of flow problems, we define and report results from a two-dimensional viscous flow around a rotating stirrer in a square chamber. The application potential of the method is demonstrated in the context of biomedical design problem, as we perform an analysis of blood flow in a centrifugal left ventricular assist device, or blood pump, which involves a rotating impeller in a non-axisymmetric housing.