Ribbon Synapses and Retinal Disease: Review.

Synaptic ribbons are presynaptic protein complexes that are believed to be important for the transmission of sensory information in the visual system. Ribbons are selectively associated with those synapses where graded changes in membrane potential drive continuous neurotransmitter release. Defective synaptic transmission can arise as a result of the mutagenesis of a single ribbon component. Visual diseases that stem from malfunctions in the presynaptic molecular machinery of ribbon synapses in the retina are rare. In this review, we provide an overview of synaptopathies that give rise to retinal malfunction and our present understanding of the mechanisms that underlie their pathogenesis and discuss muscular dystrophies that exhibit ribbon synapse involvement in the pathology.

Single-arm, neoadjuvant, phase II trial of pertuzumab and trastuzumab administered concomitantly with weekly paclitaxel followed by 5-fluoruracil, epirubicin, and cyclophosphamide (FEC) for stage I-III HER2-positive breast cancer.

PURPOSE: The purpose of this two-cohort Phase II trial was to estimate the pathologic complete response (pCR: ypT0/is ypN0) rate when trastuzumab plus pertuzumab are administered concurrently during both the taxane and anthracycline phases of paclitaxel and 5-fluorouracil/epirubicin/cyclophosphamide (FEC) neoadjuvant chemotherapy. METHODS: The pCR rates were assessed separately in hormone receptor (HR) positive and negative cases following Simon's two-stage design, aiming to detect a 20% absolute improvement in pCR rates from 50 to 70 and 70 to 90% in the HR-positive and HR-`negative cohorts, respectively. RESULTS: The HR-negative cohort completed full accrual of 26 patients; pCR rate was 80% (95% CI 60-91%). The HR+ cohort was closed early after 24 patients due to lower than expected pCR rate of 26% (95% CI 13-46%) at interim analysis. Overall, 44% of patients (n = 22/50) experienced grade 3/4 adverse events. The most common were neutropenia (n = 10) and diarrhea (n = 7). There was no symptomatic heart failure, but 28% (n = 14) had ≥ 10% asymptomatic decrease in LVEF; in one patient, LVEF decreased to < 50%. Cardiac functions returned to baseline by the next assessment in 57% (8/14) of cases. CONCLUSIONS: Eighty percent of HR-negative, HER2-positive breast cancers achieve pCR with paclitaxel/FEC neoadjuvant chemotherapy administered concomitantly with pertuzumab and trastuzumab. These results are similar to pCR rates seen in trials using HER2-targeted therapy during the taxane phase only of sequential taxane-anthracycline regimens and suggest that we have reached a therapeutic plateau with HER2-targeted therapies combined with chemotherapy in the neoadjuvant setting.

The Effects of Aging on Rod Bipolar Cell Ribbon Synapses.

The global health concern posed by age-related visual impairment highlights the need for further research focused on the visual changes that occur during the process of aging. To date, multiple sensory alterations related to aging have been identified, including morphological and functional changes in inner hair cochlear cells, photoreceptors, and retinal ganglion cells. While some age-related morphological changes are known to occur in rod bipolar cells in the retina, their effects on these cells and on their connection to other cells via ribbon synapses remain elusive. To investigate the effects of aging on rod bipolar cells and their ribbon synapses, we compared synaptic calcium currents, calcium dynamics, and exocytosis in zebrafish (Danio rerio) that were middle-aged (MA,18 months) or old-aged (OA, 36 months). The bipolar cell terminal in OA zebrafish exhibited a two-fold reduction in number of synaptic ribbons, an increased ribbon length, and a decrease in local Ca2+ signals at the tested ribbon location, with little change in the overall magnitude of the calcium current or exocytosis in response to brief pulses. Staining of the synaptic ribbons with antibodies specific for PKCa revealed shortening of the inner nuclear and plexiform layers (INL and IPL). These findings shed light on age-related changes in the retina that are related to synaptic ribbons and calcium signals.

The Effect of Black Cohosh on Ki67 expression and Tumor Volume: A Pilot Study of Ductal Carcinoma in Situ Patients.

BACKGROUND: Black cohosh (BC) (Cimicifuga racemosa) may prevent and treat breast cancer through anti-proliferative, pro-apoptotic, anti-estrogenic, and anti-inflammatory effects. This study sought to evaluate the effect of BC on tumor cellular proliferation, measured by Ki67 expression, in a pre-operative window trial of ductal carcinoma in situ (DCIS) patients. METHODS: Patients were treated pre-operatively for 2 to 6 weeks with BC extract. Eligible subjects were those who had DCIS on core biopsy. Ki67 was measured using automated quantitative immunofluorescence (AQUA) pre/post-operatively. Ki67, tumor volume, and hormone changes were assessed with 2-sided Wilcoxon signed-rank tests, α = .05. RESULTS: Thirty-one patients were treated for an average of 24.5 days (median 25; range 15-36). Ki67 decreased non-significantly (n = 26; P = .20; median pre-treatment 1280, post-treatment 859; range pre-treatment 175-7438, post-treatment 162-3370). Tumor volume, estradiol, and FSH did not change significantly. No grade 3 or 4 adverse events were reported. CONCLUSIONS: BC use showed no significant impact on cellular proliferation, tumor volume, or invasive disease upgrade rates in DCIS patients. It was well-tolerated, with no observed significant toxicities. Further study is needed to elucidate BC's role in breast cancer treatment and prevention.ClinicalTrials.gov Identifier: NCT01628536https://clinicaltrials.gov/ct2/show/NCT01628536.

Neoadjuvant durvalumab plus weekly nab-paclitaxel and dose-dense doxorubicin/cyclophosphamide in triple-negative breast cancer.

The goal of this Phase I/II trial is to assess the safety and efficacy of administering durvalumab concurrent with weekly nab-paclitaxel and dose-dense doxorubicin/cyclophosphamide (ddAC) neoadjuvant therapy for stages I-III triple-negative breast cancer. The primary endpoint is pathologic complete response (pCR:ypT0/is, ypN0). The response was correlated with PDL1 expression and stromal tumor-infiltrating lymphocytes (sTILs). Two dose levels of durvalumab (3 and 10 mg/kg) were assessed. PD-L1 was assessed using the SP263 antibody; ≥1% immune and tumor cell staining was considered positive; sTILs were calculated as the area occupied by mononuclear inflammatory cells over the total intratumoral stromal area. 59 patients were evaluable for toxicity and 55 for efficacy in the Phase II study (10 mg/kg dose). No dose-limiting toxicities were observed in Phase I. In Phase II, pCR rate was 44% (95% CI: 30-57%); 18 patients (31%) experienced grade 3/4 treatment-related adverse events (AE), most frequently neutropenia (n = 4) and anemia (n = 4). Immune-related grade 3/4 AEs included Guillain-Barre syndrome (n = 1), colitis (n = 2), and hyperglycemia (n = 2). Of the 50 evaluable patients for PD-L1, 31 (62%) were PD-L1 positive. pCR rates were 55% (95% CI: 0.38-0.71) and 32% (95% CI: 0.12-0.56) in the PD-L1 positive and negative groups (p = 0.15), respectively. sTIL counts were available on 52 patients and were significantly higher in the pCR group (p = 0.0167). Concomitant administration of durvalumab with sequential weekly nab-paclitaxel and ddAC neoadjuvant chemotherapy resulted in a pCR rate of 44%; pCR rates were higher in sTIL-high cancers.

Synaptic Ribbons Require Ribeye for Electron Density, Proper Synaptic Localization, and Recruitment of Calcium Channels.

Synaptic ribbons are structures made largely of the protein Ribeye that hold synaptic vesicles near release sites in non-spiking cells in some sensory systems. Here, we introduce frameshift mutations in the two zebrafish genes encoding for Ribeye and thus remove Ribeye protein from neuromast hair cells. Despite Ribeye depletion, vesicles collect around ribbon-like structures that lack electron density, which we term "ghost ribbons." Ghost ribbons are smaller in size but possess a similar number of smaller vesicles and are poorly localized to synapses and calcium channels. These hair cells exhibit enhanced exocytosis, as measured by capacitance, and recordings from afferent neurons post-synaptic to hair cells show no significant difference in spike rates. Our results suggest that Ribeye makes up most of the synaptic ribbon density in neuromast hair cells and is necessary for proper localization of calcium channels and synaptic ribbons.

Melanopsin ganglion cells use a membrane-associated rhabdomeric phototransduction cascade.

Intrinsically photosensitive retinal ganglion cells (ipRGCs) are photoreceptors of the mammalian eye that drive pupillary responses, synchronization of circadian rhythms, and other reflexive responses to daylight. Melanopsin is the ipRGC photopigment, but the signaling cascade through which this invertebrate-like opsin triggers the photocurrent in these cells is unknown. Here, using patch-clamp recordings from dissociated ipRGCs in culture, we show that a membrane-associated phosphoinositide cascade lies at the heart of the ipRGC phototransduction mechanism, similar to the cascade in rhabdomeric photoreceptors of invertebrate eyes. When ipRGCs were illuminated, melanopsin activated a G protein of the G(q/11) class, stimulating the effector enzyme phospholipase C. The presence of these signaling components in ipRGCs was confirmed by single-cell RT-PCR and immunofluorescence. The photoresponse was fully functional in excised inside-out patches of ipRGC membrane, indicating that all core signaling components are within or tightly coupled to the plasma membrane. The striking similarity of phototransduction in ipRGCs and invertebrate rhabdomeric photoreceptors reinforces the emerging view that these cells have a common evolutionary origin.