Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l−1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe3O4-functionalized CNTs were prepared and studied using energy-filter mapping of Fe3O4. CNTs bearing Fe3O4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up.
plants; carbon nanotubes; nanotube uptake; nanotube phytotoxicity; Raman mapping; electron microscopy
One reason for the lack of progress in the treatment of acute graft versus host disease (GVHD) is the lack of reliable biomarkers. GVHD of the gastrointestinal (GI) tract is closely associated with non-relapse mortality (NRM) following hematopoietic cell transplantation (HCT). Using an unbiased, large-scale, quantitative proteomic discovery approach, we identified candidate biomarkers that were increased in plasma from HCT patients with GI GVHD. We then validated the lead candidate, REG3α, by ELISA in samples from more than 1,000 HCT patients from three transplant centers. Plasma REG3α concentrations were 3-fold higher in patients at GI GVHD onset than in all other patients. REG3α concentrations correlated most closely with lower GI GVHD at GVHD onset and predicted response to therapy at 4 weeks, 1-year NRM, and 1-year survival (P≤0.001). Multivariate analysis showed that advanced clinical stage, severe histologic damage, and high REG3α concentrations at the diagnosis of GVHD independently predicted 1-year NRM, which progressively increased with higher numbers of onset risk factors present. We conclude that REG3α is a plasma biomarker of GI GVHD that can be combined with clinical stage and histologic grade to improve risk stratification of patients, perhaps providing a platform for advances in the treatment of high-risk GVHD.
biomarker; gastrointestinal (GI); graft versus host disease (GVHD); hematopoietic cell transplantation (HCT); REG3α
Animal models of tobacco addiction rely on administration of nicotine alone or nicotine combined with isolated constituents. Models using tobacco extracts derived from tobacco products and containing a range of tobacco constituents might more accurately simulate tobacco exposure in humans.
To compare the effects of nicotine alone and an aqueous smokeless tobacco extract in several addiction-related animal behavioral models.
Nicotine alone and nicotine dose-equivalent concentrations of extract were compared in terms of their acute effects on intracranial self-stimulation (ICSS) thresholds, discriminative stimulus effects, and effects on locomotor activity.
Similar levels of nicotine and minor alkaloids were achieved using either artificial saliva or saline for extraction, supporting the clinical relevance of the saline extracts used in these studies. Extract produced reinforcement-enhancing (ICSS threshold-decreasing) effects similar to those of nicotine alone at low to moderate nicotine doses, but reduced reinforcement-attenuating (ICSS threshold-increasing) effects at a high nicotine dose. In rats trained to discriminate nicotine alone from saline, intermediate extract doses did not substitute for the training dose as well as nicotine alone. Locomotor stimulant effects and nicotine distribution to brain were similar following administration of extract or nicotine alone.
The reinforcement-attenuating and discriminative stimulus effects of nicotine delivered in an extract of a commercial smokeless tobacco product differed from those of nicotine alone. Extracts of tobacco products may be useful for evaluating the abuse liability of those products and understanding the role of non-nicotine constituents in tobacco addiction.
Nicotine; smokeless tobacco; non-nicotine tobacco constituents; extract; intracranial self-stimulation; nicotine discrimination; locomotor sensitization
The ability of tobacco harm reduction strategies to produce significant reductions in toxin exposure is limited by compensatory increases in smoking behavior. Characterizing factors contributing to the marked individual variability in compensation may be useful for understanding this phenomenon and assessing the feasibility of harm reduction interventions.
To use an animal model of human compensatory smoking that involves a decrease in unit dose supporting nicotine self-administration (NSA) to examine potential contributors to individual differences in compensation.
Rats were trained for NSA during daily 23 hr sessions at a unit dose of 0.06 mg/kg/inf until responding was stable. The unit dose was then reduced to 0.03 mg/kg/inf for at least 10 sessions. Following reacquisition of NSA at the training dose and extinction, single-dose nicotine pharmacokinetic parameters were determined.
Decreases in nicotine intake following dose reduction were proportionally less than the decrease in unit dose, indicating partial compensation. Compensatory increases in infusion rates were observed across the course of the 23 hr sessions. The magnitude of compensation differed considerably between rats. Rats exhibiting the highest baseline infusion rates exhibited the lowest levels of compensation. Nicotine pharmacokinetic parameters were not significantly correlated with compensation. Infusion rates immediately returned to pre-reduction levels when baseline conditions were restored.
These findings provide initial insights into correlates of individual differences in compensation following a reduction in nicotine unit dose. The present assay may be useful for characterizing mechanisms and potential consequences of the marked individual differences in compensatory smoking observed in humans.
Nicotine; Self-administration; Rat; Harm Reduction; Compensation
Compensatory smoking may represent an adverse consequence of smoking reduction or the use of reduced nicotine tobacco products. Factors contributing to individual variability in compensation are poorly understood.
To examine whether severity of nicotine withdrawal as measured by elevated intracranial self-stimulation (ICSS) thresholds is related to individual differences in compensatory nicotine self-administration (NSA) following unit dose reduction.
Rats were trained for ICSS and NSA (0.06 mg/kg/inf). After stabilization, effects of reducing the nicotine unit dose to 0.03 mg/kg/inf were examined. Following reacquisition of NSA (0.06 mg/kg/inf), effects of antagonist-precipitated withdrawal and saline extinction (spontaneous withdrawal) were examined.
Reducing the NSA unit dose produced partial compensation as indicated by increased infusion rates but a 35% mean decrease in daily nicotine intake. Magnitude of compensation varied considerably among rats. Dose reduction did not elicit withdrawal in rats as a group, although there were substantial increases in ICSS thresholds in some animals. Intracranial self-stimulation thresholds were consistently elevated during precipitated and spontaneous withdrawal, confirming that rats were nicotine-dependent. Individual differences in compensation were not correlated with changes in ICSS thresholds during dose reduction, precipitated withdrawal, or spontaneous withdrawal. In a secondary analysis, greater precipitated withdrawal severity predicted greater initial nicotine-seeking during extinction.
Severity of nicotine withdrawal was not related to the degree of compensation in this protocol. These data do not support a role for nicotine withdrawal in individual differences in compensation during reduced nicotine exposure, but do suggest that withdrawal may contribute to nicotine-seeking during early abstinence.
Nicotine; Self-administration; Intracranial self-stimulation; Withdrawal; Tobacco harm reduction; Compensation
Actinomyosin activity is an important driver of cell locomotion and has been shown to promote collective cell migration of epithelial sheets as well as single cell migration and tumor cell invasion. However, the molecular mechanisms underlying activation of cortical myosin to stimulate single cell movement, and the relationship between the mechanisms that drive single cell locomotion and those that mediate collective cell migration of epithelial sheets are incompletely understood. Here, we demonstrate that p114RhoGEF, an activator of RhoA that associates with non-muscle myosin IIA, regulates collective cell migration of epithelial sheets and tumor cell invasion. Depletion of p114RhoGEF resulted in specific spatial inhibition of myosin activation at cell-cell contacts in migrating epithelial sheets and the cortex of migrating single cells, but only affected double and not single phosphorylation of myosin light chain. In agreement, overall elasticity and contractility of the cells, processes that rely on persistent and more constant forces, were not affected, suggesting that p114RhoGEF mediates process-specific myosin activation. Locomotion was p114RhoGEF-dependent on Matrigel, which favors more roundish cells and amoeboid-like actinomyosin-driven movement, but not on fibronectin, which stimulates flatter cells and lamellipodia-driven, mesenchymal-like migration. Accordingly, depletion of p114RhoGEF led to reduced RhoA, but increased Rac activity. Invasion of 3D matrices was p114RhoGEF-dependent under conditions that do not require metalloproteinase activity, supporting a role of p114RhoGEF in myosin-dependent, amoeboid-like locomotion. Our data demonstrate that p114RhoGEF drives cortical myosin activation by stimulating myosin light chain double phosphorylation and, thereby, collective cell migration of epithelial sheets and amoeboid-like motility of tumor cells.
In multicellular organisms, intercellular communication is essential for homeostatic functions and has a major role in tissue responses to stress. Here, we describe the effects of expression of different connexins, which form gap junction channels with different permeabilities, on the responses of human cells to ionizing radiation. Exposure of confluent HeLa cell cultures to 137Cs γ rays, 3.7 MeV α particles, 1000 MeV protons or 1000 MeV/u iron ions resulted in distinct effects when the cells expressed gap junction channels composed of either connexin26 (Cx26) or connexin32 (Cx32). Irradiated HeLa cells expressing Cx26 generally showed decreased clonogenic survival and reduced metabolic activity relative to parental cells lacking gap junction communication. In contrast, irradiated HeLa cells expressing Cx32 generally showed enhanced survival and greater metabolic activity relative to the control cells. The effects on clonogenic survival correlated more strongly with effects on metabolic activity than with DNA damage as assessed by micronucleus formation. The data also showed that the ability of a connexin to affect clonogenic survival following ionizing radiation can depend on the specific type of radiation. Together, these findings show that specific types of connexin channels are targets that may be exploited to enhance radiotherapeutic efficacy and to formulate countermeasures to the harmful effects of specific types of ionizing radiation.
gap junction permeability; cohort effects; radiotherapy; stress response; linear energy transfer/radiation quality
Nicotine vaccines have shown preliminary evidence of efficacy for enhancing smoking cessation rates, but the serum nicotine-specific antibody (NicAb) concentrations produced are highly variable and many subjects do not develop effective levels. As an alternative to vaccination, passive immunization with nicotine-specific monoclonal antibodies could produce more uniform serum NicAb concentrations, but its use is limited by their high cost and shorter elimination half-life. This study investigated supplementing vaccination with monoclonal antibodies in a targeted fashion to increase vaccine efficacy while minimizing the required monoclonal antibody dose. Rats were vaccinated and then given individualized supplemental doses of the nicotine-specific monoclonal antibody Nic311 to achieve a target total serum NicAb concentration known to be effective for blocking locomotor sensitization (LMS) to nicotine. Rats received vaccine, Nic311, both, or neither, followed by 0.3 mg/kg nicotine s.c. for 10 days to produce LMS. Combination immunotherapy completely blocked the development of LMS, while monotherapy with vaccine or Nic311 alone were only minimally effective. Lower brain nicotine levels were associated with reduced locomotor activity averaged over days 7-10. Despite its greater efficacy, combination immunotherapy did not reduce the variability in the resulting total serum NicAb concentrations. Variability in total serum NicAb concentrations was contributed to by both vaccine-generated antibody and by Nic311. These data show that combination immunotherapy, using a Nic311 dose that is by itself only minimally effective, can substantially enhance nicotine vaccine efficacy. However, variability in serum NicAb levels with combination immunotherapy may make translation of this approach challenging.
nicotine; immunotherapy; locomotor sensitization; vaccine; monoclonal antibody; pharmacokinetics
Unbiased discovery proteomics strategies have the potential to identify large numbers of novel biomarkers that can improve diagnostic and prognostic testing in a clinical setting and may help guide therapeutic interventions. When large numbers of candidate proteins are identified, it may be difficult to validate candidate biomarkers in a timely and efficient fashion from patient plasma samples that are event-driven, of finite volume and irreplaceable, such as at the onset of acute graft-versus-host disease (GVHD), a potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT).
Here we describe the process of performing commercially available ELISAs for six validated GVHD proteins: IL-2Rα5, TNFR16, HGF7, IL-88, elafin2, and REG3α3 (also known as PAP1) in a sequential fashion to minimize freeze-thaw cycles, thawed plasma time and plasma usage. For this procedure we perform the ELISAs in sequential order as determined by sample dilution factor as established in our laboratory using manufacturer ELISA kits and protocols with minor adjustments to facilitate optimal sequential ELISA performance. The resulting plasma biomarker concentrations can then be compiled and analyzed for significant findings within a patient cohort. While these biomarkers are currently for research purposes only, their incorporation into clinical care is currently being investigated in clinical trials.
This technique can be applied to perform ELISAs for multiple proteins/cytokines of interest on the same sample(s) provided the samples do not need to be mixed with other reagents. If ELISA kits do not come with pre-coated plates, 96-well half-well plates or 384-well plates can be used to further minimize use of samples/reagents.
Medicine; Issue 68; ELISA; Sequential ELISA; Cytokine; Blood plasma; biomarkers; proteomics; graft-versus-host disease; Small sample; Quantification
We investigated the roles of gap junction communication and oxidative stress in modulating potentially lethal damage repair in human fibroblast cultures exposed to doses of α particles or γ rays that targeted all cells in the cultures. As expected, α particles were more effective than γ rays at inducing cell killing; further, holding γ-irradiated cells in the confluent state for several hours after irradiation promoted increased survival and decreased chromosomal damage. However, maintaining α-particle-irradiated cells in the confluent state for various times prior to subculture resulted in increased rather than decreased lethality and was associated with persistent DNA damage and increased protein oxidation and lipid peroxidation. Inhibiting gap junction communication with 18-α-glycyrrhetinic acid or by knockdown of connexin43, a constitutive protein of junctional channels in these cells, protected against the toxic effects in α-particle-irradiated cell cultures during confluent holding. Upregulation of antioxidant defense by ectopic overexpression of glutathione peroxidase protected against cell killing by α particles when cells were analyzed shortly after exposure. However, it did not attenuate the decrease in survival during confluent holding. Together, these findings indicate that the damaging effect of α particles results in oxidative stress, and the toxic effects in the hours after irradiation are amplified by intercellular communication, but the communicated molecule(s) is unlikely to be a substrate of glutathione peroxidase.
The recently published crystal structure of the Cx26 gap junction channel provides a unique opportunity for elucidation of the structure of the conductive connexin pore and the molecular determinants of its ion permeation properties (conductance, current–voltage [I-V] relations, and charge selectivity). However, the crystal structure was incomplete, most notably lacking the coordinates of the N-terminal methionine residue, which resides within the pore, and also lacking two cytosolic domains. To allow computational studies for comparison with the known channel properties, we completed the structure. Grand canonical Monte Carlo Brownian dynamics (GCMC/BD) simulations of the completed and the published Cx26 hemichannel crystal structure indicate that the pore is too narrow to permit significant ion flux. The GCMC/BD simulations predict marked inward current rectification and almost perfect anion selectivity, both inconsistent with known channel properties. The completed structure was refined by all-atom molecular dynamics (MD) simulations (220 ns total) in an explicit solvent and POPC membrane system. These MD simulations produced an equilibrated structure with a larger minimal pore diameter, which decreased the height of the permeation barrier formed by the N terminus. GCMC/BD simulations of the MD-equilibrated structure yielded more appropriate single-channel conductance and less anion/cation selectivity. However, the simulations much more closely matched experimentally determined I-V relations when the charge effects of specific co- and posttranslational modifications of Cx26 previously identified by mass spectrometry were incorporated. We conclude that the average equilibrated structure obtained after MD simulations more closely represents the open Cx26 hemichannel structure than does the crystal structure, and that co- and posttranslational modifications of Cx26 hemichannels are likely to play an important physiological role by defining the conductance and ion selectivity of Cx26 channels. Furthermore, the simulations and data suggest that experimentally observed heterogeneity in Cx26 I-V relations can be accounted for by variation in co- and posttranslational modifications.
Glycation of horse heart metmyoglobin with D-ribose 5-phosphate (R5P), D-2-deoxyribose 5-phosphate (dR5P), and D-ribose with inorganic phosphate at 37 °C generates an altered protein (Myo-X) with increased SDS PAGE mobility. The novel protein product has been observed only for reactions with the protein myoglobin and it is not evident with other common sugars reacted over a one week period. Myo-X is first observed at 1-2 days at 37 °C along with a second form that is consistent in mass with that of myoglobin attached to several sugars. MALDI mass spectrometry and other techniques show no evidence of the cleavage of a peptide from the myoglobin chain. Apomyoglobin in reaction with R5P also exhibited this protein form suggesting its occurrence was not heme-related. While significant amounts of O2− and H2O2 are generated during the R5P glycation reaction, they do not appear to play roles in the formation of the new form. The modification is likely due to an internal cross-link formed during a glycation reaction involving the N-terminus and an internal amine group; most likely the neighboring Lys133. The study shows the unique nature of these common pentose sugars in spontaneous glycation reactions with proteins.
Glycation; ribose 5-phosphate; cross-linking; protein modification; heme degradation
The mechanisms of action of endogenous modulatory ligands of connexin channels are largely unknown. Previous work showed that protonated aminosulfonates (AS), notably taurine, directly and reversibly inhibit homomeric and heteromeric channels that contain Cx26, a widely distributed connexin, but not homomeric Cx32 channels. The present study investigated the molecular mechanisms of connexin channel modulation by taurine, using hemichannels and junctional channels composed of Cx26 (homomeric) and Cx26/Cx32 (heteromeric). The addition of a 28–amino acid “tag” to the carboxyl-terminal domain (CT) of Cx26 (Cx26T) eliminated taurine sensitivity of homomeric and heteromeric hemichannels in cells and liposomes. Cleavage of all but four residues of the tag (Cx26Tc) resulted in taurine-induced pore narrowing in homomeric hemichannels, and restored taurine inhibition of heteromeric hemichannels (Cx26Tc/Cx32). Taurine actions on junctional channels were fully consistent with those on hemichannels. Taurine-induced inhibition of Cx26/Cx32T and nontagged Cx26 junctional channels was blocked by extracellular HEPES, a blocker of the taurine transporter, confirming that the taurine-sensitive site of Cx26 is cytoplasmic. Nuclear magnetic resonance of peptides corresponding to Cx26 cytoplasmic domains showed that taurine binds to the cytoplasmic loop (CL) and not the CT, and that the CT and CL directly interact. ELISA showed that taurine disrupts a pH-dependent interaction between the CT and the CT-proximal half of the CL. These studies reveal that AS disrupt a pH-driven cytoplasmic interdomain interaction in Cx26-containing channels, causing closure, and that the Cx26CT has a modulatory role in Cx26 function.
Animal models of tobacco dependence typically rely on parenteral administration of pure nicotine. Models using cigarette smoke inhalation might more accurately simulate nicotine exposure in smokers. The primary goal of this study was to validate methods for administering cigarette smoke to rats using exposure conditions that were clinically relevant and also produced brain nicotine levels similar to those produced by behaviorally active doses of pure nicotine. A secondary goal was to begin examining the behavioral effects of smoke. Nose-only exposure (NOE) to smoke for 10–45 min or whole-body exposure (WBE) to smoke for 1–4 hr produced serum nicotine concentrations similar to those in smokers (14–55 ng/ml), without excessive carbon monoxide exposure. Daily nicotine (0.1 mg/kg, s.c.) induced locomotor sensitization whereas 45-min NOE producing brain nicotine levels within the same range did not. Nicotine 0.125 mg/kg s.c. reversed withdrawal from a chronic nicotine infusion as measured by elevations in intracranial self-stimulation thresholds whereas 4-hr WBE producing similar brain nicotine levels did not. These data demonstrate the feasibility of delivering cigarette smoke to rats at clinically relevant doses, and provide preliminary evidence that the behavioral effects of nicotine delivered in smoke may differ from those of pure nicotine.
Cigarette smoke; nicotine; pharmacokinetics; locomotor sensitization; intracranial self-stimulation; withdrawal; rat
Lava flows comprise three-phase mixtures of melt, crystals, and bubbles. While existing one-phase treatments allow melt phase viscosity to be assessed on the basis of composition, water content, and/or temperature, two-phase treatments constrain the effects of crystallinity or vesicularity on mixture viscosity. However, three-phase treatments, allowing for the effects of coexisting crystallinity and vesicularity, are not well understood. We investigate existing one- and two-phase treatments using lava flow case studies from Mauna Loa (Hawaii) and Mount Etna (Italy) and compare these with a three-phase treatment that has not been applied previously to basaltic mixtures. At Etna, melt viscosities of 425 ± 30 Pa s are expected for well-degassed (0.1 w. % H2O), and 135 ± 10 Pa s for less well-degassed (0.4 wt % H2O), melt at 1080°C. Application of a three-phase model yields mixture viscosities (45% crystals, 25–35% vesicles) in the range 5600–12,500 Pa s. This compares with a measured value for Etnean lava of 9400 ± 1500 Pa s. At Mauna Loa, the three-phase treatment provides a fit with the full range of field measured viscosities, giving three-phase mixture viscosities, upon eruption, of 110–140 Pa s (5% crystals, no bubble effect due to sheared vesicles) to 850–1400 Pa s (25–30% crystals, 40–60% spherical vesicles). The ability of the three-phase treatment to characterize the full range of melt-crystal-bubble mixture viscosities in both settings indicates the potential of this method in characterizing basaltic lava mixture viscosity.
This cross-sectional study examines the association between total prescription medication use and potentially inappropriate medication use (PIRx) among community-dwelling elderly patients with and without dementia. Data (9/2005-9/2007) were from the NIA-funded National Alzheimer's Coordinating Center Uniform Data Set (UDS). The study analyzed the UDS initial visits of 4,518 community-dwelling subjects aged 65+ with and without dementia (2,665 and 1,853, respectively). PIRx was defined using a partial list of the 2003 Beers criteria. Generalized linear mixed models were applied to estimate the association between PIRx and polypharmacy. In both groups (with and without dementia), subjects who received PIRx on average took more medications than those taking no PIRx. As the total number of medications used increased, the odds of having PIRx also increased, controlling for dementia diagnosis and other subject characteristics. Our key findings were consistent after considering two definitions of PIRx (with or without oral estrogens) and accounting for missing data. In summary, the total number of medications used is associated with PIRx among ADC's community-dwelling elderly patients with and without dementia, with polypharmacy increasing the risk of PIRx. Ensuring appropriate medication use in this population is clinically important because of the significant risks for institutionalization.
prescription drugs; Beers criteria; Alzheimer's disease
The title compound, [RuCl2(C10H14)(C6H6FN)], a pseudo-octahedral d
6 complex, has the expected piano-stool geometry around the Ru(II) atom. The fluoroaniline ring forms a dihedral angle of 19.3 (2)° with the p-cymene ring. In the crystal, two molecules form an inversion dimer via a pair of N—H⋯Cl hydrogen bonds. Weak intermolecular C—H⋯Cl interactions involving the p-cymene ring consolidate the crystal packing.
Objective To determine if senior doctors’ parking habits and skills are associated with clinical specialty and, if so, whether observation of junior doctors’ parking could provide guidance in choice of specialty.
Design Covert observational study.
Setting Pass-card controlled consultants’ car park (parking lot), December 2009.
Participants 103 consultants entering the car park on three consecutive mornings.
Main outcome measures The outcomes were specialty and sex of the consultants, manner of approaching the barrier (pass-card ready or not), and time taken to park, exit the vehicle, and walk to a designated point.
Results Approaches to the barrier and parking were recorded for 103 consultants (79 men, 24 women): 28 anaesthetists (22 men, six women), 29 physicians (internists, 18 men, 11 women), 14 radiologists (nine men, five women), and 32 surgeons (30 men, two women). The manner of approaching the barrier (card ready) differed by specialty but not by sex. The total time taken to park (seconds) differed significantly between specialties: surgery (median 68, interquartile range 61-71 seconds), anaesthesia (82, 76-91), radiology (86, 70-103), and general medicine (112, 96-136). The time taken to park was overall longer among women, but this was explained by their specialty (men and women matched by specialty did not differ).
Conclusions The total time taken to park and manner of approaching the barrier to gain entry to the car park differed across specialties. Surgical consultants were fastest, followed by consultant anaesthetists and consultant radiologists, with physicians slowest. Sex was not an influencing factor. If reproducible in studies of a similar nature the “barrier method” could allow for a low cost means of guiding junior doctors in career selection.
In recent years there has been much interest in the use of optical diagnostics in cancer detection. Early diagnosis of cancer affords early intervention and greatest chance of cure. Raman spectroscopy is based on the interaction of photons with the target material producing a highly detailed biochemical 'fingerprint' of the sample. It can be appreciated that such a sensitive biochemical detection system could confer diagnostic benefit in a clinical setting. Raman has been used successfully in key health areas such as cardiovascular diseases, and dental care but there is a paucity of literature on Raman spectroscopy in Head and Neck cancer. Following the introduction of health care targets for cancer, and with an ever-aging population the need for rapid cancer detection has never been greater. Raman spectroscopy could confer great patient benefit with early, rapid and accurate diagnosis. This technique is almost labour free without the need for sample preparation. It could reduce the need for whole pathological specimen examination, in theatre it could help to determine margin status, and finally peripheral blood diagnosis may be an achievable target.
Previous studies documented that human bladder cancer cells are sensitive to the apoptotic effects of quinazoline-derived α1-adrenoreceptor antagonists and bladder tumors exhibit reduced tissue vascularity in response to terazosin. More recent evidence suggests that exposure to quinazoline α1-adrenorecptor antagonists leads to a significant reduction in prostate cancer incidence. This retrospective observational cohort study was conducted to determine whether male patients treated with quinazoline α1-adrenoceptor antagonists for either benign prostate hyperplasia (BPH) or hypertension have a decreased risk of developing bladder cancer. Review of the medical records of all male patients enrolled at the Lexington Veterans Administration (VA) Medical Center identified men exposed to quinazoline-based α1-adrenoceptor antagonists (Jan 1, 1998-Dec 31, 2002) for either hypertension and/or benign prostate obstructive symptoms. The whole group of 27,138 male patients was linked to the Markey Cancer Center’s Kentucky Cancer Registry (KCR), part of the NCI’s Surveillance, Epidemiology, and End Results (SEER) Program, to identify all incident bladder cancer cases diagnosed in this population. Measures of disease incidence, relative risk, and attributable risk were calculated to compare the risk of developing bladder cancer for α1-blocker-exposed versus unexposed men. A two-by-two contingency table of α1-antagonist exposure versus bladder cancer diagnoses was constructed and the relative risk was calculated. Our analysis revealed a cumulative bladder cancer incidence of 0.24% among the α1-blocker-exposed men compared to 0.42% in the unexposed group. Thus, there was a risk difference of −0.0018, which indicates that 1.8 fewer bladder cancer cases developed per 1000 exposed men. Alternatively stated, 556 men would need to be treated with quinazoline α1-blockers to prevent one case of bladder cancer. Exposure to quinazoline α1-blockers thus may have prevented 7 to 8 bladder cancer cases among the 4173 treated men during the study period. The data yield an unadjusted risk ratio of 0.57 (95% CI: 0.30, 1.08) and therefore, men treated with α1-adrenoreceptor antagonists have a 43% lower relative risk of developing bladder cancer than unexposed men (p=0.083). Our inability to determine person-years at risk of developing bladder cancer for each unexposed control patient, was a limitation for calculating an incidence ratio and rate difference. These results offer an initial indication that exposure to doxazosin and terazosin decreases the incidence of bladder cancer. This is the first epidemiological evidence that the anti-tumor action of quinazoline-based α1-antagonists may potentially translate into a protective effect from bladder cancer development.
Bladder Cancer; Prevention; α1-adrenoceptor Antagonists; Apoptosis
Vaccination against nicotine is under investigation as a treatment for tobacco dependence. Passive immunization with nicotine-specific antibodies represents a complementary strategy to vaccination. A potential adverse effect of passive immunization in nicotine-dependent individuals is that it may lead to a rapid reduction in brain nicotine levels and trigger withdrawal. The goal of this study was to determine if passive immunization with the nicotine-specific monoclonal antibody Nic311 precipitated withdrawal in nicotine-dependent rats as measured by increases in brain reward thresholds and somatic signs. Another cohort of rats was used to measure brain nicotine levels after Nic311 administration. Nic311 30, 80 or 240 mg/kg reduced brain nicotine concentrations by 45, 83 or 92% compared to controls. None of these Nic311 doses precipitated withdrawal measured at intervals up to 72 hours following antibody administration. Administration of the nicotinic antagonist mecamylamine precipitated a robust nicotine withdrawal syndrome. Therefore, a substantial, but not complete, acute reduction in brain nicotine levels following passive immunization was not sufficient to precipitate nicotine withdrawal in nicotine-dependent rats. The Nic311 doses used have been shown to attenuate the behavioral effects of nicotine, suggesting that the use of passive immunization to treat nicotine addiction is not likely to precipitate withdrawal.
Nicotine; passive immunization; monoclonal antibody; withdrawal; mecamylamine
Gap junction channels connect the cytoplasms of adjacent cells through the end-to-end docking of single-membrane structures called connexons, formed by a ring of six connexin monomers. Each monomer contains 4 transmembrane α-helices, for a total of 24 α-helices in a connexon. The fundamental structure of the connexon pore is probably similar in unpaired connexons and junctional channels, and for channels formed by different connexin isoforms. Nevertheless, variability in results from structurally-focused mutagenesis and electrophysiological studies raise uncertainty about the specific assignments of the transmembrane helices. Mapping of human mutations onto a suggested Cα model predicts that mutations that disrupt helix-helix packing impair channel function. An experimentally determined structure at atomic resolution will be essential to confirm and resolve these concepts.
gap junction channel; connexon; intercellular communication; electron microscopy; mutagenesis; computational modeling