Altered synaptic connectivity and brain function in mice lacking microglial adapter protein Iba1.

Growing evidence indicates that microglia impact brain function by regulating synaptic pruning and formation as well as synaptic transmission and plasticity. Iba1 (ionized Ca+2-binding adapter protein 1), encoded by the Allograft inflammatory factor 1 (Aif1) gene, is an actin-interacting protein in microglia. Although Iba1 has long been used as a cellular marker for microglia, its functional role remains unknown. Here, we used global, Iba1-deficient (Aif1-/-) mice to characterize microglial activity, synaptic function, and behavior. Microglial imaging in acute hippocampal slices and fixed tissues from juvenile mice revealed that Aif1-/- microglia display reductions in ATP-induced motility and ramification, respectively. Biochemical assays further demonstrated that Aif1-/- brain tissues exhibit an altered expression of microglial-enriched proteins associated with synaptic pruning. Consistent with these changes, juvenile Aif1-/- mice displayed deficits in the excitatory synapse number and synaptic drive assessed by neuronal labeling and whole-cell patch-clamp recording in acute hippocampal slices. Unexpectedly, microglial synaptic engulfment capacity was diminished in juvenile Aif1-/- mice. During early postnatal development, when synapse formation is a predominant event in the hippocampus, the excitatory synapse number was still reduced in Aif1-/- mice. Together, these findings support an overall role of Iba1 in excitatory synaptic growth in juvenile mice. Lastly, postnatal synaptic deficits persisted in adulthood and correlated with significant behavioral changes in adult Aif1-/- mice, which exhibited impairments in object recognition memory and social interaction. These results suggest that Iba1 critically contributes to microglial activity underlying essential neuroglia developmental processes that may deeply influence behavior.

Machine learning approaches based on fibroblast morphometry do not predict ALS.

Amyotrophic lateral sclerosis (ALS) is a devastating neuromuscular disease with limited therapeutic options. Biomarkers are needed for early disease detection, clinical trial design, and personalized medicine. Early evidence suggests that specific morphometric features in ALS primary skin fibroblasts may be used as biomarkers; however, this hypothesis has not been rigorously tested in conclusively large fibroblast populations. Here, we imaged ALS-relevant organelles (mitochondria, endoplasmic reticulum, lysosomes) and proteins (TAR DNA-binding protein 43, Ras GTPase-activating protein-binding protein 1, heat-shock protein 60) at baseline and under stress perturbations and tested their predictive power on a total set of 443 human fibroblast lines from ALS and healthy individuals. Machine learning approaches were able to confidently predict stress perturbation states (ROC-AUC ∼0.99) but not disease groups or clinical features (ROC-AUC 0.58-0.64). Our findings indicate that multivariate models using patient-derived fibroblast morphometry can accurately predict different stressors but are insufficient to develop viable ALS biomarkers.

Germline breast cancer susceptibility genes, tumor characteristics, and survival.

BACKGROUND: Mutations in certain genes are known to increase breast cancer risk. We study the relevance of rare protein-truncating variants (PTVs) that may result in loss-of-function in breast cancer susceptibility genes on tumor characteristics and survival in 8852 breast cancer patients of Asian descent. METHODS: Gene panel sequencing was performed for 34 known or suspected breast cancer predisposition genes, of which nine genes (ATM, BRCA1, BRCA2, CHEK2, PALB2, BARD1, RAD51C, RAD51D, and TP53) were associated with breast cancer risk. Associations between PTV carriership in one or more genes and tumor characteristics were examined using multinomial logistic regression. Ten-year overall survival was estimated using Cox regression models in 6477 breast cancer patients after excluding older patients (≥75years) and stage 0 and IV disease. RESULTS: PTV9genes carriership (n = 690) was significantly associated (p < 0.001) with more aggressive tumor characteristics including high grade (poorly vs well-differentiated, odds ratio [95% confidence interval] 3.48 [2.35-5.17], moderately vs well-differentiated 2.33 [1.56-3.49]), as well as luminal B [HER-] and triple-negative subtypes (vs luminal A 2.15 [1.58-2.92] and 2.85 [2.17-3.73], respectively), adjusted for age at diagnosis, study, and ethnicity. Associations with grade and luminal B [HER2-] subtype remained significant after excluding BRCA1/2 carriers. PTV25genes carriership (n = 289, excluding carriers of the nine genes associated with breast cancer) was not associated with tumor characteristics. However, PTV25genes carriership, but not PTV9genes carriership, was suggested to be associated with worse 10-year overall survival (hazard ratio [CI] 1.63 [1.16-2.28]). CONCLUSIONS: PTV9genes carriership is associated with more aggressive tumors. Variants in other genes might be associated with the survival of breast cancer patients. The finding that PTV carriership is not just associated with higher breast cancer risk, but also more severe and fatal forms of the disease, suggests that genetic testing has the potential to provide additional health information and help healthy individuals make screening decisions.

Cohort profile: The Singapore Breast Cancer Cohort (SGBCC), a multi-center breast cancer cohort for evaluation of phenotypic risk factors and genetic markers.

This article aims to provide a detailed description of the Singapore Breast Cancer Cohort (SGBCC), an ongoing multi-ethnic cohort established with the overarching goal to identify genetic markers for breast cancer risk, prognosis and treatment response, as well as to understand the ethnic differences in disease risk and outcome in an Asian setting. The cohort comprises of breast cancer patients aged 21 years and above from six public hospitals which diagnose and treat nearly 76% breast cancer cases in Singapore. Self-reported data on sociodemographic and lifestyle, reproductive risk factors, medical history and family history of breast or ovarian cancer is collected using a structured questionnaire. Clinical data on tumour characteristics, and treatment modalities are obtained through medical record. Bio-specimens (blood or saliva) is collected at recruitment. Follow-up on survival information is done through routine linkage with the Registry of Births and Deaths. As of 31 December 2016, 7,768 subjects have been recruited to the study with 76% subjects contributed bio-specimens. The SGBCC provides a valuable platform which offers a unique, large and rich resource for new research ideas on breast cancer related phenotypic risk factors and genetic markers.

Treatment of recalcitrant air leaks: the combined latissimus dorsi-serratus anterior flap.

Pleural space problems after lung resection and persistent air leaks are among the commonest challenges posed to thoracic surgeons. Surgical repair of air leaks are indicated when conventional tube thoracostomy has failed to solve the problem. We would like to propose the novel application of the combined latissimus dorsi-serratus anterior transposition flap for selected cases of air leaks that are recalcitrant to conventional treatment. We discuss its indications and the surgical technique. Five patients underwent the procedure between 2004 and 2007. They were male patients aged between 32 and 70 years. Four patients had alveolar-pleural fistulas resulting in persistent air leaks while the fifth patient had, in addition, a space problem following lung volume reduction surgery. All patients had prolonged treatment with chest drains without success. With the patient in a lateral decubitus position, a lazy-S incision was used to expose the entire latissimus dorsi and the proximal slips of the serratus anterior muscles. They were raised as pedicled flaps and transferred in tandem. The latissimus dorsi was introduced into the pleural cavity via a thoracic window and used to reinforce the fistula repair. The serratus anterior muscle closed the rib window. In all cases, the lungs reexpanded and chest drains were removed within 5 days post surgery. There were no recurrent air leaks at 1-year follow-up with all patients. Conservative treatment in all our patients was unsuccessful. The dual flap technique has the advantage of allowing normal ventilation while providing a seal over the alveolar-pleural fistula. The muscle bulk of the latissimus dorsi fills the pleural dead space and the serratus anterior muscle seals the axilla preventing subcutaneous emphysema. There was minimal morbidity associated with the use of this dual muscle flap technique. This technique is an effective treatment option for recalcitrant air leaks.

From skin allograft coverage to allograft-micrograft sandwich method: A retrospective review of severe burn patients who received conjunctive application of cultured epithelial autografts.

A 12-year retrospective review of severe burn patients who received cultured epithelial autografts (CEA) at the Singapore General Hospital Burns Centre from January 2005 to December 2016 was carried out. During this period, two different surgical modalities were employed to manage these burn injuries. In the earlier period, following early excision of the burn wounds, exposed surfaces were covered with a combination of split thickness skin autografts (STSG) and allografts. Surfaces covered with skin allografts were subsequently debrided of the allo-epidermis in about 3 weeks later, exposing the allodermis with granulating tissues for grafting of CEA; a technique known as the Cuono's method. In the later period, allograft-autologous micrograft sandwich technique was used to graft on the early excised burns with subsequent CEA grafting. The former and latter groups represented by STSG/C (n=10) and M/CEA (n=14) respectively, were compared in terms of clinical profiles, outcomes, allograft/CEA usage and total graft cost. No significant differences were found based on mean age and presence of inhalation burns between the two treatment methods However, percentage total body surface area (TBSA) and Revised Baux Score were significantly higher (p<0.05) in the M/CEA group compared to the STSG/C group. Differences in clinical outcomes of mortality and length of hospital stay between the 2 groups were statistically insignificant. The average area amount of skin allografts used per patient in the M/CEA group was significantly lower compared to the STSG/C method group which contributed to lower total average cost of grafts used per % TBSA in the M/CEA method group. This might be attributed to the presence of micrografts which seemed to improve stabilization of the wound bed resulting in less operating procedures and improving CEA take. To conclude, the M/CEA method introduced was able to treat more severe burn patients at lower graft costs without compromising critical clinical outcomes significantly.

Outcome after neoadjuvant chemotherapy in Asian breast cancer patients.

We aim to identify clinicopathologic predictors for response to neoadjuvant chemotherapy and to evaluate the prognostic value of pathologic complete response (pCR) on survival in Asia. This study included 915 breast cancer patients who underwent neoadjuvant chemotherapy at five public hospitals in Singapore and Malaysia. pCR following neoadjuvant chemotherapy was defined as 1) no residual invasive tumor cells in the breast (ypT0/is) and 2) no residual invasive tumor cells in the breast and axillary lymph nodes (ypT0/is ypN0). Association between pCR and clinicopathologic characteristics and treatment were evaluated using chi-square test and multivariable logistic regression. Kaplan-Meier analysis and log-rank test, stratified by other prognostic factors, were conducted to compare overall survival between patients who achieved pCR and patients who did not. Overall, 4.4% of nonmetastatic patients received neoadjuvant chemotherapy. The median age of preoperatively treated patients was 50 years. pCR rates were 18.1% (pCR ypT0/is) and 14.4% (pCR ypT0/is ypN0), respectively. pCR rate was the highest among women who had higher grade, smaller size, estrogen receptor negative, human epidermal growth factor receptor 2-positive disease or receiving taxane-based neoadjuvant chemotherapy. Patients who achieved pCR had better overall survival than those who did not. In subgroup analysis, the survival advantage was only significant among women with estrogen receptor-negative tumors. Patients with poor prognostic profile are more likely to achieve pCR and particularly when receiving taxane-containing chemotherapy. pCR is a significant prognostic factor for overall survival especially in estrogen receptor-negative breast cancers.

Local hypocretin-1 modulates terminal dopamine concentration in the nucleus accumbens shell.

Hypocretins (hcrt), also known as orexins, play a critical role in reward-seeking behavior for natural rewards and drugs of abuse. The mesolimbic dopamine pathway that projects from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) is critically involved in the neural mechanisms underlying reward-seeking and motivation. Hcrt immunopositive fibers densely project to the shell of the nucleus accumbens (NAcSh), suggesting that the NAcSh might be a site for the interaction between hcrt and dopaminergic modulation of reward-seeking behavior. While it is known that hcrt action in the VTA can increase dopamine in the NAc, it has not been determined if hcrt released locally at dopaminergic terminals in the NAcSh can modulate dopamine concentration. Here, we use fast scan cyclic voltammetry (FSCV) in forebrain slices containing the NAcSh to determine whether hcrt can alter evoked dopamine concentration. We found bath application of hcrt-1 increases phasically evoked dopamine release, without altering reuptake at dopamine terminals in the NAcSh. Hcrt-1-induced potentiation of dopamine concentration was inhibited by SB334867, a hcrt receptor 1 antagonist, as well as ionotropic glutamate receptor antagonists, AP-5, CNQX and DNQX. Taken together, these results suggest that local hcrt-1 can modulate dopamine in the NAcSh and may play a role in reward-seeking and appetitive behaviors.

Use of the extended V-Y latissimus dorsi myocutaneous flap for chest wall reconstruction in locally advanced breast cancer.

The extended V-Y latissimus dorsi myocutaneous flap described by Micali and Carramaschi provides an innovative method of closing large anterior chest defects after resection of breast cancer. The technique provides robust chest wall coverage that is able to withstand immediate postoperative radiotherapy. The aim of this article is to confirm the usefulness of the flap's design and describe modifications to the technique. The modifications to technique include: a curvilinear design that recruited more skin for closure in patients with wounds extending laterally or superiorly, routine transposition of latissimus dorsi insertion inferio-medially onto the chest wall to maximize pedicle reach, and the use of small split skin grafts or delayed primary closure if there was tension in closing. Twelve patients who underwent resection of locally advanced breast cancer had immediate chest wall reconstruction with the extended V-Y latissimus dorsi musculocutaneous flap. The V to Y design of the flap's cutaneous island allowed primary closure of chest wound and donor defect. There were no instances of chest wound dehiscence. The chest wounds healed, allowing patients to undergo adjuvant radiotherapy in a mean time interval of 6 weeks after surgery.