398 research outputs found
VDAC1 (voltage-dependent anion channel 1)
Review on VDAC1 (voltage-dependent anion channel 1), with data on DNA, on the protein encoded, and where the gene is implicated
Involvement of protein phosphorylation in activation of Ca2+ efflux from sarcoplasmic reticulum
Characterization of Ca2+-dependent endogenous phosphorylation of 160,000- and 150,000-Dalton proteins of sarcoplasmic reticulum
Characterization of high-affinity ryanodine-binding sites of rat liver endoplasmic reticulum. Differences between liver and skeletal muscle
The Use of Anti-VDAC2 Antibody for the Combined Assessment of Human Sperm Acrosome Integrity and Ionophore A23187-Induced Acrosome Reaction
Voltage-dependent anion channel (VDAC) is mainly located in the mitochondrial outer membrane and participates in many biological processes. In mammals, three VDAC subtypes (VDAC1, 2 and 3) have been identified. Although VDAC has been extensively studied in various tissues and cells, there is little knowledge about the distribution and function of VDAC in male mammalian reproductive system. Several studies have demonstrated that VDAC exists in mammalian spermatozoa and is implicated in spermatogenesis, sperm maturation, motility and fertilization. However, there is no knowledge about the respective localization and function of three VDAC subtypes in human spermatozoa. In this study, we focused on the presence of VDAC2 in human spermatozoa and its possible role in the acrosomal integrity and acrosome reaction using specific anti-VDAC2 monoclonal antibody for the first time. The results exhibited that native VDAC2 existed in the membrane components of human spermatozoa. The co-incubation of spermatozoa with anti-VDAC2 antibody did not affect the acrosomal integrity and acrosome reaction, but inhibited ionophore A23187-induced intracellular Ca2+ increase. Our study suggested that VDAC2 was located in the acrosomal membrane or plasma membrane of human spermatozoa, and played putative roles in sperm functions through mediating Ca2+ transmembrane transport
International consensus on (ICON) anaphylaxis
ICON: Anaphylaxis provides a unique perspective on the principal evidence-based anaphylaxis guidelines developed and published independently from 2010 through 2014 by four allergy/immunology organizations. These guidelines concur with regard to the clinical features that indicate a likely diagnosis of anaphylaxis -- a life-threatening generalized or systemic allergic or hypersensitivity reaction. They also concur about prompt initial treatment with intramuscular injection of epinephrine (adrenaline) in the mid-outer thigh, positioning the patient supine (semi-reclining if dyspneic or vomiting), calling for help, and when indicated, providing supplemental oxygen, intravenous fluid resuscitation and cardiopulmonary resuscitation, along with concomitant monitoring of vital signs and oxygenation. Additionally, they concur that H1-antihistamines, H2-antihistamines, and glucocorticoids are not initial medications of choice. For self-management of patients at risk of anaphylaxis in community settings, they recommend carrying epinephrine auto-injectors and personalized emergency action plans, as well as follow-up with a physician (ideally an allergy/immunology specialist) to help prevent anaphylaxis recurrences. ICON: Anaphylaxis describes unmet needs in anaphylaxis, noting that although epinephrine in 1 mg/mL ampules is available worldwide, other essentials, including supplemental oxygen, intravenous fluid resuscitation, and epinephrine auto-injectors are not universally available. ICON: Anaphylaxis proposes a comprehensive international research agenda that calls for additional prospective studies of anaphylaxis epidemiology, patient risk factors and co-factors, triggers, clinical criteria for diagnosis, randomized controlled trials of therapeutic interventions, and measures to prevent anaphylaxis recurrences. It also calls for facilitation of global collaborations in anaphylaxis research. In addition to confirming the alignment of major anaphylaxis guidelines, ICON: Anaphylaxis adds value by including summary tables and citing 130 key references. It is published as an information resource about anaphylaxis for worldwide use by healthcare professionals, academics, policy-makers, patients, caregivers, and the public
Cisplatin and Oxaliplatin Toxicity: Importance of Cochlear Kinetics as a Determinant for Ototoxicity
Background
Cisplatin is a commonly used platinum anti-cancer drug. Regrettably cisplatin
has dose-limiting ototoxic side effects, e.g. the drug can induce an irreversible
hearing loss. The ototoxic mechanisms of cisplatin have not been
elucidated in the human ear and no clinically useful oto-protectors are yet
available. Cisplatin is a necessary part of many treatment regimes. Its beneficial
therapeutic effects might be reduced if cisplatin was excluded from the
treatment in order to protect the hearing function. In this work the ototoxic
effects of cisplatin are studied with the aim to better understand the mechanisms
behind the irreversible hearing loss induced by this drug. Oxaliplatin is
a second generation platinum-derivative anti-cancer drug, free from ototoxic
side effects in clinical practice. The effects of oxaliplatin on the inner ear have
been studied in this work and the results are compared with cisplatin treatment.
The two drugs differ regarding both anti-cancer effects and side effects,
which could be attributed to differences in pharmacokinetic factors, cellular
uptake and apoptotic mechanisms. The thioredoxin redox system with the
enzyme thioredoxin reductase (TrxR) was studied in cochleae due to a suggested
DNA-independent apoptotic mechanism of the hair cells. The cochlear
pharmacokinetics of cisplatin was assessed and the transport protein organic
cation transporter 2 (OCT2) was studied in relation to the ototoxic effect of
cisplatin.
Material and methods
Cultured human colon carcinoma cells and cell cultures of rat organ of Corti
were used for apoptosis studies in vitro following exposure to cisplatin and
oxaliplatin. Cisplatin and oxaliplatin were administered i.v. to guinea pigs,
followed by in vivo sampling of blood, cerebrospinal fluid (CSF) and scala
tympani (ST) perilymph. Liquid chromatography with post-column derivatization
was used to determine the concentration of parent drug in the samples.
Electrophysiological hearing thresholds and the loss of hair cells were assessed
to evaluate their ototoxic effects. Phenformin, a potential blocker of
OCT2 was administered and the ototoxic side effect of cisplatin was evaluated.
For immunohistochemical studies, cochlea from rat, guinea pig and pig
were used, where TrxR and OCT2 were evaluated in the cochlea. TrxR-assays
were used to measure the TrxR activity in cochlear tissue, both in vivo and in
vitro.
Results
The results from the in vitro studies showed that addition of either cisplatin
or oxaliplatin to the culture medium in organ of Corti cell cultures caused a
similar amount of outer hair cell loss and inhibition of TrxR activity. Cisplatin
exposure to cultured human colon carcinoma cells also reduced the activity
of TrxR. The results from the in vivo studies showed that a considerable concentration
of cisplatin was present in ST perilymph as compared with weak
concentrations of oxaliplatin after high dose oxaliplatin i.v. Ten minutes after
cisplatin administration, its concentration in ST perilymph was 4-fold higher
in the basal turn of the cochlea as compared to the apex. Cisplatin could be
analysed in ST perilymph for up to 120 min. Phenformin i.v. did not reduce
the ototoxic side-effect of cisplatin. Positive immunoreactivity to TrxR was
evident in both hair cells and spiral ganglion cells. Futhermore, OCT2 was
expressed in the supporting cells of organ of Corti and in the spiral ganglion
cells.
Conclusion
The transport of cisplatin to the vulnerable cells of hearing seems to be of major
importance for the ototoxic effects. An early high concentration of cisplatin
in the base of the cochlea and delayed elimination of cisplatin from ST perilymph
may be related to the cisplatin-induced loss of outer hair cells in the
basal turn of the cochlea. Cisplatin and oxaliplatin both cause similar ototoxic
effects when the organ of Corti is directly exposed in vitro. The thioredoxin
redox system with the TrxR enzyme may well play a critical role in cisplatininduced
ototoxicity. The presence of OCT2 in the supporting cells indicates
that this transport protein is primarily not involved in the uptake of cisplatin
from the systemic circulation but rather from the deeper compartments of
the cochlea. The knowledge elicited in this work will hopefully suggest objectives
for further studies in order to develop oto-protective treatments to
preserve the hearing of cisplatin treated patients
MAP4 Mechanism that Stabilizes Mitochondrial Permeability Transition in Hypoxia: Microtubule Enhancement and DYNLT1 Interaction with VDAC1
Mitochondrial membrane permeability has received considerable attention recently because of its key role in apoptosis and necrosis induced by physiological events such as hypoxia. The manner in which mitochondria interact with other molecules to regulate mitochondrial permeability and cell destiny remains elusive. Previously we verified that hypoxia-induced phosphorylation of microtubule-associated protein 4 (MAP4) could lead to microtubules (MTs) disruption. In this study, we established the hypoxic (1% O2) cell models of rat cardiomyocytes, H9c2 and HeLa cells to further test MAP4 function. We demonstrated that increase in the pool of MAP4 could promote the stabilization of MT networks by increasing the synthesis and polymerization of tubulin in hypoxia. Results showed MAP4 overexpression could enhance cell viability and ATP content under hypoxic conditions. Subsequently we employed a yeast two-hybrid system to tag a protein interacting with mitochondria, dynein light chain Tctex-type 1 (DYNLT1), by hVDAC1 bait. We confirmed that DYNLT1 had protein-protein interactions with voltage-dependent anion channel 1 (VDAC1) using co-immunoprecipitation; and immunofluorescence technique showed that DYNLT1 was closely associated with MTs and VDAC1. Furthermore, DYNLT1 interactions with MAP4 were explored using a knockdown technique. We thus propose two possible mechanisms triggered by MAP4: (1) stabilization of MT networks, (2) DYNLT1 modulation, which is connected with VDAC1, and inhibition of hypoxia-induced mitochondrial permeabilization
Mitochondria Express α7 Nicotinic Acetylcholine Receptors to Regulate Ca2+ Accumulation and Cytochrome c Release: Study on Isolated Mitochondria
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that mediate synaptic transmission in the muscle and autonomic ganglia and regulate transmitter release in the brain. The nAChRs composed of α7 subunits are also expressed in non-excitable cells to regulate cell survival and proliferation. Up to now, functional α7 nAChRs were found exclusively on the cell plasma membrane. Here we show that they are expressed in mitochondria and regulate early pro-apoptotic events like cytochrome c release. The binding of α7-specific antibody with mouse liver mitochondria was revealed by electron microscopy. Outer membranes of mitochondria from the wild-type and β2−/− but not α7−/− mice bound α7 nAChR-specific antibody and toxins: FITC-labeled α-cobratoxin or Alexa 555-labeled α-bungarotoxin. α7 nAChR agonists (1 µM acetylcholine, 10 µM choline or 30 nM PNU-282987) impaired intramitochondrial Ca2+ accumulation and significantly decreased cytochrome c release stimulated with either 90 µM CaCl2 or 0.5 mM H2O2. α7-specific antagonist methyllicaconitine (50 nM) did not affect Ca2+ accumulation in mitochondria but attenuated the effects of agonists on cytochrome c release. Inhibitor of voltage-dependent anion channel (VDAC) 4,4′-diisothio-cyano-2,2′-stilbene disulfonic acid (0.5 µM) decreased cytochrome c release stimulated with apoptogens similarly to α7 nAChR agonists, and VDAC was co-captured with the α7 nAChR from mitochondria outer membrane preparation in both direct and reverse sandwich ELISA. It is concluded that α7 nAChRs are expressed in mitochondria outer membrane to regulate the VDAC-mediated Ca2+ transport and mitochondrial permeability transition
Serum S100B levels after meningioma surgery: A comparison of two laboratory assays
<p>Abstract</p> <p>Background</p> <p>S100B protein is a potential biomarker of central nervous system insult. This study quantitatively compared two methods for assessing serum concentration of S100B.</p> <p>Methods</p> <p>A prospective, observational study performed in a single tertiary medical center. Included were fifty two consecutive adult patients undergoing surgery for meningioma that provided blood samples for determination of S100B concentrations. Eighty samples (40 pre-operative and 40 postoperative) were randomly selected for batch testing. Each sample was divided into two aliquots. These were analyzed by ELISA (Sangtec) and a commercial kit (Roche Elecsys<sup>®</sup>) for S100B concentrations. Statistical analysis included regression modelling and Bland-Altman analysis.</p> <p>Results</p> <p>A parsimonious linear model best described the prediction of commercial kit values by those determined by ELISA (y = 0.045 + 0.277*x, x = ELISA value, R<sup>2 </sup>= 0.732). ELISA measurements tended to be higher than commercial kit measurements. This discrepancy increased linearly with increasing S100B concentrations. At concentrations above 0.7 μg/L the paired measurements were consistently outside the limits of agreement in the Bland-Altman display. Similar to other studies that used alternative measurement methods, sex and age related differences in serum S100B levels were not detected using the Elecsys<sup>® </sup>(p = 0.643 and 0.728 respectively).</p> <p>Conclusion</p> <p>Although a generally linear relationship exists between serum S100B concentrations measured by ELISA and a commercially available kit, ELISA values tended to be higher than commercial kit measurements particularly at concentrations over 0.7 μg/L, which are suggestive of brain injury. International standardization of commercial kits is required before the predictive validity of S100B for brain damage can be effectively assessed in clinical practice.</p
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