Panobinostat (LBH589)-induced acetylation of tubulin impairs megakaryocyte maturation and platelet formation

Drug-induced thrombocytopenia often results from dysregulation of normal megakaryocytopoiesis. In this study, we investigated the mechanisms responsible for thrombocytopenia associated with the use of Panobinostat (LBH589), a histone deacetylase inhibitor with promising anti-cancer activities. The effects of LBH589 were tested on the cellular and molecular aspects of megakaryocytopoiesis by utilizing an ex vivo system in which mature megakaryocytes (MK) and platelets were generated from human primary CD34(+) cells. We demonstrated that LBH589 did not affect MK proliferation or lineage commitment but inhibited MK maturation and platelet formation. Although LBH589 treatment of primary MK resulted in hyperacetylation of histones, it did not interfere with the expression of genes that play important roles during megakaryocytopoiesis. Instead, we found that LBH589 induced post-translational modifications of tubulin, a nonhistone protein that is the major component of the microtubule cytoskeleton. We then demonstrated that LBH589 treatment induced hyperacetylation of tubulin and alteration of microtubule dynamics and organization required for proper MK maturation and platelet formation. This study provides new insights into the mechanisms underlying LBH589-induced thrombocytopenia and provides a rationale for using tubulin as a target for selective histone deacetylase inhibitor therapies to treat thrombocytosis in patients with myeloproliferative neoplasms.     

Validation of a Weight History Questionnaire to Identify Adolescent Obesity

Background

Past body weight may be a more informative factor than current weight for risk of chronic disease development. Often, investigators must rely on subject recall to gauge past body weights. The Cincinnati Weight History Questionnaire (CWHQ) was developed to aid in the retrospective identification of adults who were obese during adolescence.

Methods

To assess validity, the CWHQ was administered to a subset of National Heart, Lung, and Blood Growth and Health Study (NGHS) participants, a group of young adult females for whom historical measured anthropometrics were available. One hundred ninety-eight NGHS participants were contacted, of whom 191 (97 %) responded (age 26–29). Participants were asked to recall height and weight from ages 13 and 18, which were compared to previously measured values. Multiple indices of validity (Bland–Altman plots, sensitivity, and specificity) were calculated.

Results

The CWHQ was moderately sensitive (range, 19–66 %), but highly specific (range, 89–100 %). Recalled height and weight values used to determine body mass index (BMI) underestimated BMI based on recorded height and weight at ages 13 and 18. Differences in calculated BMI based on recalled and measured height and weight were found to increase with BMI calculated using measured values.

Conclusions

The CWHQ proved to be a moderately sensitive, but highly specific instrument for detecting adolescent obesity in a cohort of young adult females. Epidemiologic research seeking to discriminate between adults with adult-onset vs. adolescent-onset obesity may find the CWHQ useful.     

Laparoscopic Colorectal Surgery for Obese Patients: Decreased Conversions with the Hand-Assisted Technique

Background

Laparoscopic surgery benefits obese patients but technical difficulties associated with suboptimal exposure and access in these subjects may prompt conversion to open surgery. Hand-assisted laparoscopic surgery (HALS) confers advantages over standard laparoscopy (LAP) by facilitating tactile feedback, assisted dissection, and retraction. These benefits could be particularly valuable in obese patients, allowing completion of difficult laparoscopic procedures in this subgroup. Our aim was to compare intra-operative and post-operative outcomes of HALS and LAP approaches in obese patients undergoing colorectal resection at our institution.

Methods

A retrospective study of a prospectively maintained laparoscopic colorectal surgery database was performed. HALS and LAP cases performed in obese patients (body mass index (BMI)?>30) were identified and compared for the following outcomes: operative time, intra-operative complications, rate of conversion to open, blood loss, length of stay, post-operative morbidity, and mortality. Outcomes for the converted patients were included on an intention-to-treat basis for all primary analyses. A secondary analysis of nonconverted and converted cases was also performed.

Results

Over a 5-year period, 496 obese patients underwent laparoscopic colorectal resection; 86 HALS and 410 LAP cases. The two groups were comparable in terms of age, gender, BMI, and indications for surgery. Conversion to open surgery was less often necessary in HALS compared to LAP cases (3.5 % vs. 12.7 %, p?=?0.014). The LAP group had a significantly smaller incision length for specimen extraction (HALS (7.0?±?1.3 cm) vs. LAP (5.7?±?2.1 cm), p?<?0.001). Length of stay, operative time, morbidity, and mortality rates were comparable between the two groups.

Conclusion

In obese patients who require colectomy, the HALS approach increases the likelihood of a successful minimally invasive operation. At the cost of a clinically negligible increase in incision length, HALS may save a high-risk group conversion to formal laparotomy and the adverse outcomes related to this.     

Hepatic Hemodynamic Changes Following Stepwise Liver Resection

Aim

Extended liver resection has increased during the last decades. However, hepatic hemodynamic changes after resection and the consequent complications like post hepatectomy liver failure are still a challenging issue. The aim of this study was to systematically evaluate the role of stepwise liver resection on hepatic hemodynamic changes.

Methods

To evaluate this effect we performed 25, 50, and 75 % sequential liver resections in 10 pigs. Before and after each resection, the hepatic artery flow and portal vein flow in relation to the remnant liver volume (RLV) as well as hepatic vascular pressures were measured and compared between the groups.

Results

Following sequential liver resection, the hepatic artery flow /100 g decreases and the portal vein flow increases up to 17 and 167 % following extended liver resection (75 %), respectively. Also, during stepwise liver resection, the portal vein pressure increases gradually up to 33 % following extended hepatectomy (75 %).

Conclusion

Sequential decrease in the RLV decreases the hepatic artery flow /100 g and increases the portal vein flow /100 g and portal vein pressure. As the consequence, the liver goes under more poor-oxygenated blood supply and higher pressure. This may be one of the most important mechanisms of the post hepatectomy liver failure in case of extended liver resection.

     

Application of salivary noncoding microRNAs for the diagnosis of oral cancers

Oral cancer is on the rise globally and survival rates, despite improvements in clinical care, have not significantly improved. Early detection followed by immediate intervention is key to improving patient outcomes. The use of biomarkers has changed the diagnostic landscape for many cancers. For oral cancers, visual inspection followed by a tissue biopsy is standard practice. The discovery of microRNAs as potential biomarkers has attracted clinical interest but several challenges remain. These microRNAs can be found in bodily fluids such as blood and saliva which have been investigated as potential sources of biomarker discovery. As oral cancer is localized within the oral cavity, saliva may contain clinically relevant molecular markers for disease detection. Our review provides an outline of the current advances for the application of salivary microRNAs in oral cancer. We also provide a technical guide for the processing of salivary RNAs to ensure accurate clinical measurement and validation.