The X-ray structure of the papillomavirus helicase in complex with its molecular matchmaker E2

DNA replication of the papillomaviruses is specified by cooperative binding of two proteins to the ori site: the enhancer E2 and the viral initiator E1, a distant member of the AAA+ family of proteins. Formation of this prereplication complex is an essential step toward the construction of a functional, multimeric E1 helicase and DNA melting. To understand how E2 interacts with E1 to regulate this process, we have solved the X-ray structure of a complex containing the HPV18 E2 activation domain bound to the helicase domain of E1. Modeling the monomers of E1 to a hexameric helicase shows that E2 blocks hexamerization of E1 by shielding a region of the E1 oligomerization surface and stabilizing a conformation of E1 that is incompatible with ATP binding. Further biochemical experiments and structural analysis show that ATP is an allosteric effector of the dissociation of E2 from E1. Our data provide the first molecular insights into how a protein can regulate the assembly of an oligomeric AAA+ complex and explain at a structural level why E2, after playing a matchmaker role by guiding E1 to the DNA, must dissociate for subsequent steps of initiation to occur. Building on previously proposed ideas, we discuss how our data advance current models for the conversion of E1 in the prereplication complex to a hexameric helicase assembly.     

Use of reboxetine in bulimia nervosa: a pilot study

The pharmacological approach to bulimia nervosa is mainly based (BN) on selective serotonin reuptake inhibitors, but many elements suggest the possible involvement of the noradrenergic system in this disorder. The aim of the study was to assess the efficacy of reboxetine--a selective norepinephrine uptake inhibitor--in a sample of bulimic outpatients, after 3 months of treatment. Twenty-eight of 77 consecutively admitted patients with a DSM-IV diagnosis of BN (without Axis I comorbidity) received reboxetine. All patients were assessed at baseline (T0), and after 1 month (T1) and 3 months (T3), respectively, of treatment with reboxetine 4 mg/day. The subjects were administered the following questionnaires: Hamilton Rating Scale for Anxiety (HAM-A) and for Depression (HAM-D), Global Assessment Functioning (GAF), Eating Disorder Inventory-2 (EDI-2) and Body Shape Questionnaire (BSQ). Sixty percent of the patients were responsive to treatment(evaluated as a 50% decrease of bulimic behaviours). After 3 months of treatment, a significant reduction emerged in the scores of various EDI-2 subscales (Bulimia, Drive for Thinness, Body Dissatisfaction, Social Insecurity, Interpersonal Distrust, etc.) and in the BSQ total score. Moreover, depressive symptoms (HAM-D) and Global Functioning (GAF) scores showed a significant improvement. These data support a fast and favourable effect of reboxetine in the treatment of BN, both on symptoms and psychopathological features. Moreover, the specific and strong action of reboxetine on improvement of social functioning is also supported in this disorder.     

Quality of life and personality disorders in heroin abusers

OBJECTIVE: The aim of this study is to describe the personality disorders (PD) and personality profile of heroin-abusers and their quality of life (QoL), and to investigate the correlation between the two. METHOD: One hundred and eighty heroin-abusers during their residential treatment participated in the study. The Structured Clinical Interview-II (SCID-II) allowed the identification of two subgroups of heroin-abusers on the basis of presence/absence of a PD. All patients filled in the Temperament and Character Inventory (TCI), the McGill QoL Questionnaire (MQOL) and an anamnestic sheet. A control group of 63 non-clinical subjects was recruited. RESULTS: Abusers with a PD differ in their personality profile from abusers without PD and score lower on the total MQOL. As regards TCI scales, novelty seeking (NS), reward dependence (RD) and self-directedness (SD) predict the age of onset of the abuse, while cooperativeness (C) is a predictor of the number of community admissions. DISCUSSION: Low scores on self-directedness and cooperativeness in abusers support the hypothesis of an immature character and relational difficulties. Novelty seeking is the only dimension which is altered both in abusers with and without a PD and is not strictly dependent on Axis II comorbidity. QoL is lower in abusers than in controls, according to their physical, psychological and existential suffering. Last, an interesting link emerged between personality and perceived QoL.     

Regulation of myoplasmic Ca(2+) in genetically obese (ob/ob) mouse single skeletal muscle fibres

The present study examined whether calcium handling in skeletal muscle fibres from ob/ob mice was abnormal compared to normal mice. Simultaneous measurements of free myoplasmic calcium and force were made in mouse single intact muscle fibres at rest, during repetitive stimulation and for 30 min afterwards. Fibres were subjected to two bouts of intermittent tetanic contractions 1 h apart. The first bout consisted of 50 tetani only, while during the second bout stimulation was continued until force fell to 40% of control. During a bout of 50 repeated contractions, muscle fibres from ob/ob mice were unable to maintain basal calcium and tetanic calcium transients. During a second series of contractions, muscle fibres from ob/ob mice showed a marked improvement in calcium handling compared to the first series but still fatigued more rapidly than control fibres. It is concluded that calcium handling in skeletal muscle fibres from ob/ob mice is abnormal compared to fibres from normal mice and this contributes to premature fatigue.     

Multidrug-resistant tuberculosis in HIV-negative patients,Buenos Aires,Argentina

Initial multidrug-resistant (MDR) tuberculosis (TB) in HIV-negative patients treated at a Buenos Aires referral hospital from 1991 to 2000 was examined by using molecular clustering of available isolates. Of 291 HIV-negative MDRTB patients, 79 were initially MDR. We observed an ascending trend of initial MDRTB during this decade (p=0.0033). The M strain, which was responsible for an institutional AIDS-associated outbreak that peaked in 1995 to 1997, caused 24 of the 49 initial MDRTB cases available for restriction fragment length polymorphism. Of those, 21 were diagnosed in 1997 or later. Hospital exposure increased the risk of acquiring M strain-associated MDRTB by approximately two and a half times. The emergence of initial MDRTB among HIV-negative patients after 1997 was apparently a sequel of the AIDS-related outbreak. Because the prevalence of M strain-associated disease in the study population did not level out by the end of the decade, further expansion of this disease is possible.     

Rituximab in idiopathic membranous nephropathy: a one-year prospective study

Currently available monoclonal antibodies against the B cell surface antigen CD20 have been employed to explore whether specific inhibition of B cells may help improve the outcome of idiopathic membranous nephropathy (IMN) and may avoid the side effects of steroids and immunosuppressants. This prospective, observational study evaluated the 1-yr outcome of eight IMN patients with persistent (>6 mo) urinary protein excretion > 3.5 g/24 h given four weekly infusions of the anti-CD20 antibody rituximab (375 mg/m(2)). At 3 and 12 mo, proteinuria significantly decreased from mean (+/- SD) 8.6 +/- 4.2 to 4.3 +/- 3.3 (-51%, P < 0.005) and 3.0 +/- 2.5 (-66%, P < 0.005) g/24 h, albumin fractional clearance from 2.3 +/- 2.1 to 1.2 +/- 1.7 (-47%, P < 0.05) and 0.5 +/- 0.6 (-76%, P < 0.003), and serum albumin concentration increased from 2.7 +/- 0.5 to 3.1 +/- 0.3 (+21%, P < 0.05) and 3.5 +/- 0.4 (+41%, P < 0.05) mg/dl. At 12 mo, proteinuria decreased to < or =0.5 g/24 h or < or =3.5 g/24 h in two and three patients, respectively. Proteinuria decreased in the remaining patients by 74%, 44%, and 41%, respectively. Body weight, diastolic BP, and serum cholesterol progressively decreased in parallel with an improvement of edema in all patients. Renal function stabilized (Delta1/creatinine: +0.002 +/- 0.007). CD20 B lymphocytes fell below normal ranges up to study-end. No patient had major drug-related events or major changes in other laboratory parameters. Rituximab thus promotes sustained disease remission in patients otherwise predicted to progress to ESRD, and it is safe. The long-term risk/benefit profile of this novel, disease-specific approach seems much more favorable to that of commonly employed immunosuppressive drugs.