Analysis of the Lack of Follow-Up of Bariatric Surgery Patients: Experience of a Reference Center.

Few studies have evaluated the association between non-clinical and clinical determinants in terms of discontinuing follow-up after bariatric surgery. This cohort study aims to assess these associations. Data were collected from a prospectively maintained database of patients who underwent laparoscopic bariatric surgery from January 2012 to December 2019. The Cox model was used to assess the influence of preoperative determinants on follow-up interruptions for more than one year. Multilevel logistic regression was used to evaluate the association between clinical factors and post-operative weight loss with the regularity of follow-up. During the study period, 9607 consultations were performed on 1549 patients. The factors associated with a follow-up interruption from more than 365 days included male gender (HR = 1.323; CI = 1.146−1.527; p = 0.001) and more recent years of intervention (HR = 1.043; CI = 1.012−1.076; p = 0.0068). Revisional bariatric surgery was associated with a lower risk of follow-up interruption (HR = 0.753; CI = 0.619−0.916; p = 0.0045). Independent risk factors of an irregular follow up were higher age (HR = 1.01; CI = 1.002−1.017; p = 0.0086); male gender (OR = 1.272; CI = 1.047−1.545; p = 0.0153); and higher %TWL (Total Weight Loss) (OR = 1.040 CI = 1.033−1.048 p < 0.0001). A higher preoperative BMI (OR = 0.985; CI = 0.972−0.998; p = 0.0263) and revisional surgery (OR = 0.707; CI = 0.543−0.922; p = 0.0106) were protective factors of irregularity. This study suggests that the male gender and most recent dates of surgery are the two independent risk factors for follow-up interruption. Older age, male gender, and higher weight loss were all independent risk factors of an irregular follow-up. Revision bariatric surgery is a protective factor against interruption and irregular follow-up with a higher preoperative BMI. Further studies are needed to obtain long-term results in these patients with discontinued follow-ups.

Evidence for adaptation from standing genetic variation on an antimicrobial peptide gene in the mussel Mytilus edulis.

Genome scans of population differentiation identify candidate loci for adaptation but provide little information on how selection has influenced the genetic structure of these loci. Following a genome scan, we investigated the nature of the selection responsible for the outlying differentiation observed between populations of the marine mussel Mytilus edulis at a leucine/arginine polymorphism (L31R) in the antimicrobial peptide MGD2. We analysed DNA sequence polymorphisms, allele frequencies and population differentiation of polymorphisms closely linked to L31R, and pairwise and third-order linkage disequilibria. An outlying level of population differentiation was observed at L31R only, while no departure from panmixia was observed at linked loci surrounding L31R, as in most of the genome. Selection therefore seems to affect L31R directly. Three hypotheses can explain the lack of differentiation in the chromosomal region close to L31R: (i) hitchhiking has occurred but migration and recombination subsequently erased the signal, (ii) selection was weak enough and recombination strong enough to limit the hitchhiking effect to a very small chromosomal region or (iii) selection acted on a pre-existing polymorphism (i.e. standing variation) at linkage equilibrium with its background. Linkage equilibrium was observed between L31R and linked polymorphisms in every population analysed, as expected under the three hypotheses. However, linkage disequilibrium was observed in some populations between pairs of loci located upstream and downstream to L31R, generating a complex pattern of third-order linkage disequilibria which is best explained by the hypothesis of selection on a pre-existing polymorphism. We hypothesise that selection could be either balanced, maintaining alleles at different frequencies depending on the pathogen community encountered locally by mussels, or intermittent, resulting in sporadic fluctuations in allele frequency.

Crystal structure of the coiled-coil dimerization motif of geminin: structural and functional insights on DNA replication regulation.

We have determined the crystal structure of the coiled-coil domain of human geminin, a DNA synthesis inhibitor in higher eukaryotes. We show that a peptide encompassing the five heptad repeats of the geminin leucine zipper (LZ) domain is a dimeric parallel coiled coil characterized by a unique pattern of internal polar residues and a negatively charged surface that may target the basic domain of interacting partners. We show that the LZ domain itself is not sufficient to inhibit DNA synthesis but upstream and downstream residues are required. Analysis of a functional form of geminin by density sedimentation indicates an oligomeric structure. X-ray solution scattering experiments performed on a non-functional form of geminin having upstream basic residues and the LZ domain show a tetramer structure. Altogether, these results give a consistent identification and mapping of geminin interacting regions onto structurally important domains. They also suggest that oligomerization properties of geminin may be implicated in its inhibitory activity of DNA synthesis.

Great saphenous vein leiomyosarcoma: a rare malignant tumor of the extremity--two case reports.

Peripheral vascular leiomyosarcomas are rare. Two cases of intramural leiomyosarcomas of the great saphenous vein are described. The first case is considered a high-grade sarcoma, based on the high mitotic index on histologic study. The second case presents only infrequent mitoses on light microscopy. Immunohistochemical analysis for factor VIII helped to establish the diagnosis. Characteristics of the tumor and differential diagnosis are discussed. Treatment consisted of wide local excision. Radiotherapy and chemotherapy were given to the patient with high-grade tumor.

The H-NS dimerization domain defines a new fold contributing to DNA recognition.

H-NS, a protein found in Gram-negative bacteria, is involved in structuring the bacterial chromosome and acts as a global regulator for the expression of a wide variety of genes. These functions are correlated with both its DNA-binding and oligomerization properties. We have identified the minimal dimerization domain of H-NS, a 46 amino acid-long N-terminal fragment, and determined its structure using heteronuclear NMR spectroscopy. The highly intertwined structure of the dimer, reminiscent of a handshake, defines a new structural fold, which may offer a possibility for discriminating prokaryotic from eukaryotic proteins in drug design. Using mutational analysis, we also show that this N-terminal domain actively contributes to DNA binding, conversely to the current paradigm. Together, our data allows us to propose a model for the action of full length H-NS.