Type II antithrombin deficiency caused by a large in‐frame insertion: structural,functional and pathological relevance

Summary. Background: The metastable native conformation of serpins is required for their protease inhibition mechanism, but also renders them vulnerable to missense mutations that promote protein misfolding with pathological consequences. Objective: To characterize the first antithrombin deficiency caused by a large in‐frame insertion. Patients/Methods: Functional, biochemical and molecular analysis of the proband and relatives was performed. Recombinant antithrombin was expressed in HEK‐EBNA cells. Plasma and recombinant antithrombins were purified and sequenced by Edman degradation. The stability was evaluated by calorimetry. Reactive centre loop (RCL) exposure was determined by thrombin cleavage. Mutant antithrombin was crystallized as a dimer with latent plasma antithrombin. Results: The patient, with a spontaneous pulmonary embolism, belongs to a family with significant thrombotic history. We identified a complex heterozygous in‐frame insertion of 24 bp in SERPINC1, affecting strand 3 of β‐sheet A, a region highly conserved in serpins. Surprisingly, the insertion resulted in a type II antithrombin deficiency with heparin binding defect. The mutant antithrombin, with a molecular weight of 59 kDa, had a proteolytic cleavage at W49 but maintained the N‐terminal disulphide bonds, and was conformationally sensitive. The variant was non‐inhibitory. Analysis of the crystal structure of the hyperstable recombinant protein showed that the inserted sequence annealed into β‐sheet A as the fourth strand, and maintained a native RCL. Conclusions: This is the first case of a large in frame‐insertion that allows correct folding, glycosylation, and secretion of a serpin, resulting in a conformationally sensitive non‐inhibitory variant, which acquires a hyperstable conformation with a native RCL.     

Acute surgical unit safely reduces unnecessary after-hours cholecystectomy

Introduction

The acute surgical model has been trialled in several institutions with mixed results. The aim of this study was to determine whether the acute surgical model provides better outcomes for patients with acute biliary presentation, compared with the traditional emergency surgery model of care.

Methods

A retrospective review was carried out of patients who were admitted for management of acute biliary presentation, before and after the establishment of an acute surgical unit (ASU). Outcomes measured were time to operation, operating time, after-hours operation (6pm – 8am), length of stay and surgical complications.

Results

A total of 342 patients presented with acute biliary symptoms and were managed operatively. The median time to operation was significantly reduced in the ASU group (32.4 vs 25.4 hours, p=0.047), as were the proportion of operations performed after hours (19.5% vs 2.5%, p<0.001) and the median length of stay (4 vs 3 days, p<0.001). The median operating time, rate of conversion to open cholecystectomy and wound infection rates remained similar.

Conclusions

Implementation of an ASU can lead to objective differences in outcomes for patients who present with acute cholecystitis. In our study, the ASU significantly reduced time to operation, the number of operations performed after hours and length of stay.     

Role of presynaptic purinoceptors and cyclic AMP on the noradrenaline release in cat cerebral arteries

Field electrical stimulation (ES), K+ (50 mM) or ionophore X-537A (0.01 mM) induced tritium release from cat cerebral arteries preincubated with [3H]noradrenaline (NA). Adenosine and AMP (0.5 mM) did not modify tritium release caused by ionophore X-537A, but these agents and ATP (0.5 mM) significantly reduced that elicited by ES and K+; this reduction was antagonized by 1-methyl-3-isobutylxanthine (MIX; 0.05 mM). Inosine (0.5 mM) and the agonist of purinergic A2-receptors, 5'N-ethyl-carboxamide adenosine (NECA; 0.5 mM) had no effect, but the agonist of purinergic A2-receptors L-N6-phenylisopropyl adenosine (L-PIA; 0.1 mM) diminished tritium efflux caused by ES and K+. The adenosine inhibition of ES-induced radioactivity release was not affected by indomethacin (0.05 mM). MIX (0.05 mM) increased tritium release evoked by ES and K+. Agents that increase intracellular cyclic (c)AMP levels, such as dibutyryl cAMP (0.5 mM), the phosphodiesterase inhibitor Ro 20-1724 (0.1 mM), and the activators of adenylate cyclase, forskolin (0.005 mM) and NaF (2 mM) reduced tritium secretion elicited by ES and K+. However, the intracellular increase of cyclic GMP (cGMP) caused by 8-Br-cGMP did not affect this secretion. Dipyridamole (0.05 mM) and the adenosine deaminase inhibitor erythro-9-2-hydroxy-3 nonyl adenosine (EHNA; 0.1 mM) also produced inhibition of tritium secretion elicited by ES and K+. Dipyridamole reduced both the uptake of [3H]NA and [3H]adenosine.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparative double-blind study of terbinafine (Lamisil) and griseofulvin in tinea corporis and tinea cruris

In a double-blind randomized study, 92 patients with culturally proven tinea corporis and/or tinea cruris were treated orally with either terbinafine (Lamisil) (125 mg b.i.d.) or griseofulvin (500 mg b.i.d.) for up to 6 weeks. The two groups of patients and distribution of the target lesions were similar, but the analysis of the clinical scores showed that the terbinafine group had slightly higher mean scores at baseline (P = 0.186). At the end of therapy the proportion of patients with negative microscopy and culture was 78% in the terbinafine group and 83% in the griseofulvin-treated group. At the assessment 8 weeks after the end of therapy the percentages of terbinafine- and griseofulvin-treated patients with negative mycology were 93 and 95%, respectively. There were three relapses after mycological cure in the griseofulvin group (8%) and two in the terbinafine group (4%). Griseofulvin-treated patients were treated for shorter periods than terbinafine-treated patients (i.e. 58% compared to 26% received only 2-4 weeks of therapy). In terms of overall effectiveness, there were no significant differences between the two treatments. Thirty-seven terbinafine patients (77%) compared to 36 griseofulvin patients (82%) had overall effective therapy. Eight terbinafine patients (16%) compared to 10 griseofulvin patients (20%) experienced at least one adverse event. Five patients in the terbinafine group and six in the griseofulvin group had to stop the treatment due to headaches or gastrointestinal disorders. One terbinafine patient had an elevation of liver function tests after 6 weeks of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)