The huntingtin interacting protein HIP1 is a clathrin and alpha-adaptin-binding protein involved in receptor-mediated endocytosis

The huntingtin interacting protein (HIP1) is enriched in membrane-containing cell fractions and has been implicated in vesicle trafficking. It is a multidomain protein containing an N-terminal ENTH domain, a central coiled-coil forming region and a C-terminal actin-binding domain. In the present study we have identified three HIP1 associated proteins, clathrin heavy chain and alpha-adaptin A and C. In vitro binding studies revealed that the central coiled-coil domain is required for the interaction of HIP1 with clathrin, whereas DPF-like motifs located upstream to this domain are important for the binding of HIP1 to the C-terminal 'appendage' domain of alpha-adaptin A and C. Expression of full length HIP1 in mammalian cells resulted in a punctate cytoplasmic immunostaining characteristic of clathrin-coated vesicles. In contrast, when a truncated HIP1 protein containing both the DPF-like motifs and the coiled-coil domain was overexpressed, large perinuclear vesicle-like structures containing HIP1, huntingtin, clathrin and endocytosed transferrin were observed, indicating that HIP1 is an endocytic protein, the structural integrity of which is crucial for maintenance of normal vesicle size in vivo.     

Clinical presentation of celiac disease and the diagnostic accuracy of serologic markers in children

There has been growing recognition of a changing clinical presentation of celiac disease (CD), with the manifestation of milder symptoms. Serologic testing is widely used to screen patients with suspected CD and populations at risk. The aim of this retrospective analysis was to evaluate the clinical presentation of CD in childhood, assess the diagnostic value of serologic tests, and investigate the impact of IgA deficiency on diagnostic accuracy. We evaluated 206 consecutive children with suspected CD on the basis of clinical symptoms and positive serology results. Ninety-four (46%) had biopsy-proven CD. The median age at diagnosis of CD was 6.8 years; 15% of the children were <2 years of age. There was a higher incidence of CD in girls (p = 0.003). Iron deficiency and intestinal complaints were more frequent in children with CD than those without CD (61% vs. 33%, p = 0.0001 and 71% vs. 55%, p = 0.02, respectively), while failure to thrive was less common (35% vs. 53%, p = 0.02). The sensitivity of IgA tissue transglutaminase (IgA-tTG) was 0.98 when including all children and 1.00 after excluding children with selective IgA deficiency. The specificity of IgA-tTG was 0.73 using the recommended cut-off value of 20 IU, and this improved to 0.94 when using a higher cut-off value of 100 IU. All children with CD and relative IgA deficiency (IgA levels that are measurable but below the age reference [n = 8]) had elevated IgA-tTG. In conclusion, CD is frequently diagnosed in school-age children with relatively mild symptoms. The absence of intestinal symptoms does not preclude the diagnosis of CD; many children with CD do not report intestinal symptoms. While the sensitivity of IgA-tTG is excellent, its specificity is insufficient for the diagnostic confirmation of a disease requiring life-long dietary restrictions. Children with negative IgA-tTG and decreased but measurable IgA values are unlikely to have CD.     

Isolation of a lysogenic bacteriophage carrying the stx(1(OX3)) gene, which is closely associated with Shiga toxin-producing Escherichia coli strains from sheep and humans.

A specific PCR for the detection of a variant of the gene encoding Shiga toxin 1 (stx(1)) called stx(1(OX3)) (GenBank accession no. Z36901) was developed. The PCR was used to investigate 148 Stx(1)-producing Escherichia coli strains from human patients (n = 72), cattle (n = 27), sheep (n = 48), and a goat (n = 1) for the presence of the stx(1(OX3)) gene. The stx(1(OX3)) gene was present in 38 Shiga toxin-producing E. coli (STEC) strains from sheep belonging to serogroups O5, O125, O128, O146, and OX3 but was absent from Stx(1)-positive ovine STEC O91 strains. The stx(1(OX3)) gene was also detected in 22 STEC strains from humans with nonbloody diarrhea and from asymptomatic excreters. Serotypes O146:H21 and O128:H2 were most frequently associated with stx(1(OX3))-carrying STEC from sheep and humans. In contrast, Stx(1)-producing STEC strains from cattle and goats and 50 STEC strains from humans were all negative for the stx(1(OX3)) gene. The stx(1(OX3))-negative strains belonged to 13 serotypes which were different from those of the stx(1(OX3))-positive STEC strains. Moreover, the stx(1(OX3)) gene was not associated with STEC belonging to enterohemorrhagic E. coli (EHEC) serogroups O26, O103, O111, O118, O145, and O157. A bacteriophage carrying the stx(1(OX3)) gene (phage 6220) was isolated from a human STEC O146:H21 strain. The phage was able to lysogenize laboratory E. coli K-12 strain C600. Phage 6220 shared a similar morphology and a high degree of DNA homology with Stx(2)-encoding phage 933W, which originates from EHEC O157. In contrast, few similarities were found between phage 6220 and Stx(1)-encoding bacteriophage H-19B from EHEC O26.     

Edge-to-Edge Mitral Valve Repair With Extended Clip Arms: Early Experience From a Multicenter Observational Study

ObjectivesThe aim of this study was to investigate the technical success and efficacy of mitral valve edge-to-edge repair using extended clip arms.BackgroundA new iteration of the MitraClip system, the MitraClip XTR, was introduced in 2018 with the aim of addressing technical limitations observed with previous versions.MethodsPatients having received at least 1 new implant for the treatment of symptomatic mitral regurgitation (MR) were eligible for this study.ResultsAmong the 107 patients (mean age 76 ± 9 years, 69% men) included in this study, the etiology of MR was balanced, with one-half (n = 53 [50%]) classified as secondary and the remaining 54 patients having either primary (n = 40 [37%]) or mixed (n = 14 [13%]) disease. The mean number of devices implanted was 1.5 ± 0.6. Multiple device implantation was required in 46 patients (43%). Single-leaflet device attachment occurred in 4 patients and leaflet injury in 2 additional patients, requiring surgical conversion in 4 patients. Among the 102 patients discharged alive without mitral valve surgery, 95 (93%) had MR ≤2+ and 79 (77%) had MR ≤1+. The mean transmitral gradient increased from 1.9 ± 1.0 mm Hg at baseline to 3.5 ± 1.8 mm Hg at discharge (p < 0.001).ConclusionsTechnical success with the new mitral valve repair system with extended clip arm was achieved in 93% of the patients. MR ≤2+ was obtained in 95 patients (93%) and MR ≤1+ in 79 (77%). The main reasons for procedural failure were acute single-leaflet device attachment associated with leaflet damage or isolated leaflet injury and often required surgical correction.     

Physiological and Clinical Consequences of Right Ventricular Volume Overload Reduction After Transcatheter Treatment for Tricuspid Regurgitation

ObjectivesThis study sought to examine the impact of chronic right ventricular (RV) volume overload and implications of tricuspid regurgitation (TR) reduction on biventricular function.BackgroundSevere TR is a major determinant of adverse outcomes in advanced heart failure patients. The understanding of TR pathophysiology and implications of correction is still limited. Transcatheter tricuspid edge-to-edge repair (TTVR) is a new treatment option in patients at high surgical risk and provides a unique pathophysiological model without confounding effects of cardiac surgery.MethodsTwenty-nine patients (78 ± 4 years of age) with severe isolated TR and high surgical risk underwent TTVR using the MitraClip system, and of these 18 underwent repeated cardiac magnetic resonance. Clinical follow-up was realized at 1 and 6 months after the intervention.ResultsTR fraction was reduced from 41% to 21% (p < 0.01) without increase in RV afterload (p = 0.52) and RV end-diastolic volume (p < 0.01), and RV stroke volume decreased (p = 0.03), whereas RV effective forward flow increased (p = 0.03). Left ventricular (LV) filling improved with an increase in LV end-diastolic volume (p = 0.01) and LV stroke volume (p = 0.02), leading to an augmentation of cardiac indices (2.2 ± 0.6 l/min/m² vs. 2.7 ± 0.6 l/min/m²; p < 0.01) with similar results at 6 months follow-up. After TTVR, New York Heart Association functional class significantly improved (p < 0.01), peripheral edema decreased (p = 0.01), and 6-min walk distance increased by 20% and 22% after 1 and 6 months, respectively (p < 0.01).ConclusionsTTVR reduces chronic RV volume overload without increase in RV afterload, improves RV performance and LV filling, and enhances cardiac output. These changes translate into symptomatic and functional improvement. These implications for biventricular physiology and clinical status are maintained at 6 months follow-up.