Increased Nectin-4 levels in chronic ketamine abusers and the relationship with lower urinary tract symptoms

Persistent ketamine use causes susceptibility to addiction and bladder toxicity. We examined the association of lower urinary tract symptoms and levels of Nectin-4, a member of the cell adhesion molecules that is essential for maintaining the urothelium barrier in chronic ketamine abusers. We measured the plasma levels of Nectin-4 in 88 patients with ketamine dependence and 69 controls. Patients with ketamine dependence were assessed for ketamine use variables, psychological symptoms, and lower urinary tract symptoms. We found Nectin-4 levels were increased in ketamine-dependent patients compared to the controls (p < 0.0001). Patients with urinary tract symptoms exhibited lower Nectin-4 levels than those without (p = 0.021). Our results suggest an up-regulation of Nectin-4 following chronic and heavy ketamine use. Patients with ketamine dependence with a compromised upregulation of Nectin-4 are likely to have more severe urinary tract symptoms. The mechanisms underlying the involvement of Nectin-4 in ketamine addiction and bladder toxicity warrant future investigation.

Genetic variants in NECTIN4 encoding an adhesion molecule are associated with continued opioid use

Methadone is a synthetic opioid used as maintenance treatment for patients addicted to heroin. Skin irritation is one of the adverse events caused by opioid use. 344 methadone maintenance treatment (MMT) patients were recruited with records and measurements on methadone dose, plasma methadone concentrations, and treatment emergent symptom scales (TESS). 15 patients reported with skin irritation. Five SNPs located within the NECTIN4 genetic region were genotyped. The NECTIN4 gene within the adherens junction interaction pathway was associated with methadone dose in pathway-based genome wide association analyses (P = 0.0008). Three highly-linked SNPs, rs11265549, rs3820097, and rs4656978, were significantly associated with methadone dose (P = 0.0003), plasma concentrations of R,S-methadone (P = 0.0004) and TNF-α (P = 0.010) in all 344 MMT patients, and with self-report skin irritation symptom scores (P = 0.010) in the 15 MMT patients who reported with skin irritation. To identify the possible roles of plasma level of Nectin-4 in the responses to MMT and opioid use, additional age- and gender-matched 51 controls and 83 methadone-free abstinent former heroin users were recruited. Plasma level of Nectin-4 was the highest in MMT patients among the three groups. The results suggest involvement of genetic variants on NECTIN4 in methadone dose. Plasma Nectin-4 level is likely an indicator for continued use of opioids.

Adhesion Molecules as Potential Novel Biomarkers for Opioid Dependence

BACKGROUND

Cell-cell adhesion is essential in maintaining the structure and function of an organ. Several adhesion molecules have recently been identified as associated with heroin dependence in both genetic and peripheral plasma studies.

METHODS AND RESULTS

We reviewed literature concerning studies on adhesion molecules in opioid addictions in rodents and human, including human genetic associations in different ethnic groups, and treatment responses to methadone maintenance treatment in heroin-dependent patients.

CONCLUSION

Some important and novel findings were summarized and discussed. Adhesion molecules in the peripheral plasma, e.g., cadherin-2 (CDH2), may be biomarkers for both methadone treatment outcome and nectin 4 may be an indicator for continued opioid use. Neural cell adhesion molecule (NCAM) in the central nervous system may regulate opioid withdrawal and analgesic responses. Future studies to uncover the mechanisms underlying the involvement of adhesion molecules in the pathological process of addictions will be an important research direction in the field.

A Post-hoc Study of D-Amino Acid Oxidase in Blood as an Indicator of Post-stroke Dementia

Stroke is an important risk factor for dementia. Epidemiological studies have indicated a high incidence of dementia in stroke patients. There is currently no effective biomarker for the diagnosis of post-stroke dementia (PSD). D-amino acid oxidase (DAO) is a flavin-dependent enzyme widely distributed in the central nervous system. DAO oxidizes D-amino acids, a process which generates neurotoxic hydrogen peroxide and leads to neurodegeneration. This study aimed to examine post-stroke plasma DAO levels as a biomarker for PSD. In total, 53 patients with PSD, 20 post-stroke patients without dementia (PSNoD), and 71 age- and gender-matched normal controls were recruited. Cognitive function was evaluated at more than 30 days post-stroke. Plasma DAO was measured using the enzyme-linked immunosorbent assay. White matter hyperintensity (WMH), a neuroimaging biomarker of cerebral small vessel diseases, was determined by magnetic resonance imaging. We found that plasma DAO levels were independently higher in PSD subjects than in PSNoD subjects or the controls and were correlated with the WMH load in stroke patients. Using an area under the curve (AUC)/receiver operating characteristic analysis, plasma DAO levels were significantly reliable for the diagnosis of PSD. The sensitivity and specificity of the optimal cut-off value of 321 ng/ml of plasma DAO for the diagnosis of PSD were 75 and 88.7%, respectively. In conclusion, our data support that plasma DAO levels were increased in PSD patients and correlated with brain WMH, independent of age, gender, hypertension, and renal function. Plasma DAO levels may therefore aid in PSD diagnosis.

GRK5 Is Associated with the Regulation of Methadone Dosage in Heroin Dependence

Background

There is no countable biomarker for opioid dependence treatment responses thus far. In this study, we recruited Taiwanese methadone maintenance treatment patients to search for genes involving the regulatory mechanisms of methadone dose by genome-wide association analyses.

Methods

A total of 344 Taiwanese methadone maintenance treatment patients were included in a genome-wide association study. The involvement of GRK5 in opioid dependence was then further confirmed by gene expression study on lymphoblastoid cell lines derived from 3 independent age- and gender-matched groups: methadone maintenance treatment patients, medication-free former heroin abusers, and normal controls.

Results

The results indicated that GRK5, the gene encoding an enzyme related to μ-opioid receptor desensitization, is associated with methadone dose by additive model of gene-based association analysis (P=6.76×10-5). We found that 6 of the 55 single nucleotide polymorphisms from the genome-wide genotype platform and 2 single nucleotide polymorphisms from the 29 additionally selected single nucleotide polymorphisms were significantly associated with methadone maintenance dose in both genotype and allele type (P ≤ .006), especially in patients who tested negative in the urine morphine test. The levels of GRK5 gene expression were similar between methadone maintenance treatment patients and medication-free former heroin abusers. However, the normal controls showed a significantly lower level of GRK5 gene expression than the other groups (P=.019).

Conclusions

The results suggested an important role for GRK5 in the regulatory mechanisms of methadone dose and course of heroin dependence.

APBB2 is associated with amphetamine use and plasma beta-amyloids in patients receiving methadone maintenance treatment

APBB2, amyloid beta (A4) precursor protein-binding family B member 2, has been reported to be associated with opioid dependence. In this study, we reported the first time that the genetic variants in the APBB2 gene were associated with use of amphetamine in opioid dependent patients undergoing methadone maintenance treatment (MMT). 344 heroin-dependent patients undergoing MMT were recruited and assessed for use of amphetamine and opioids by urine toxicology, withdrawal severity, and side effects. DNAs were genome-widely genotyped for all patients. Single nucleotide polymorphisms (SNPs) in APBB2 were selected for association analyses for methadone treatment responses. Gene expression levels of APBB2 were measured by real-time polymerase chain reaction (PCR) in the EBV-transformed lymphoblastoids from patients. MMT patients who used amphetamine showed a significantly higher percentage of positive results in the urine morphine test (P=0.005), and insomnia (P=0.018). In single locus association analyses, SNPs rs3935357 and rs4861075 located at intron 6 were significantly associated with amphetamine use in both genotype and allele type (general linear model (GLM), P=0.0003, and 0.0002 for genotype, and 0.0003, and 0.002 for allele type, respectively). The major allele type carriers had twice risk of amphetamine use compared to the minor allele type carriers. Subjects with the TT genotype of rs4861075 showed significantly higher levels of APBB2 gene expression in both total (P=0.02) and long-form (P=0.037) than those with CC genotype. Detailed mechanisms underlying the association of APBB2 with amphetamine use and level of plasma amyloid beta in MMT patients require further investigation.

Inflammatory chemokine eotaxin-1 is correlated with age in heroin dependent patients under methadone maintenance therapy

BACKGROUND

Degeneration of central neurons and fibers has been observed in postmortem brains of heroin dependent patients. However, there are no biomarkers to predict the severity of neurodegeneration related to heroin dependence. A correlation has been reported between inflammatory C-C motif chemokine ligand 11 (CCL11, or eotaxin-1) and neurodegeneration in Alzheimer's disease.

METHODS

Three-hundred-forty-four heroin dependent, Taiwanese patients under methadone maintenance treatment (MMT) were included with clinical assessment and genomics information. Eighty-seven normal control subjects were also recruited for comparison.

RESULTS

Using receiver operating characteristics curve analyses, CCL11 showed the strongest sensitivity and specificity in correlation with age by a cut-off at 45 years (AUC = 0.69, P < 0.0001) in MMT patients, but not normal controls. Patients 45 years of age or older had significantly higher plasma levels of CCL11, fibroblast growth factor 2 (FGF-2), nicotine metabolite cotinine, and a longer duration of addiction. Plasma level of CCL11 was correlated with that of FGF-2 (partial r² = 0.24, P < 0.0001). Carriers with the mutant allele of rs1129844, a functional single nucleotide polymorphism (Ala23Thr) in the CCL11 gene, showed a higher plasma level of Aß42, ratio of Aß42/Aß40, and insomnia side effect symptom score than the GG genotype carriers among MMT responders with morphine-negative urine results.

CONCLUSIONS

The results suggest possible novel mechanisms mediated through CCL11 involving neurotoxicity in heroin dependent patients.

Missense mutation at CLDN8 associated with a high plasma interferon gamma-inducible protein 10 level in methadone-maintained patients with urine test positive for morphine

We previously reported a high plasma chemokine interferon gamma-inducible protein 10 (IP-10) level and prolonged electrocardiography QT-interval in methadone maintenance treatment (MMT) patients with HIV or HCV infection. The purpose of this study was to evaluate the genetic association of high plasma IP-10 level in the MMT patients. The gene-based and pathway-based association analyses were conducted using a genome-wide association study dataset in 344 MMT patients for identifying genes and pathways associated with plasma IP-10 level. We found that plasma IP-10 level was significantly associated with a pathway in the tight junction (P = 1.01x10-5), where the claudin 8 (CLDN8) gene had the most significant association (P = 6.8x10-5). A functional single nucleotide polymorphism (SNP) rs686364 at exon 1 of CLDN8 showed strong association with plasma IP-10 levels, in the MMT subjects with positive urine test for morphine (dominant model, P = 0.00004). The minor allele type carriers had higher plasma IP-10 levels than the major allele type carriers. Our data support that the tight junction protein claudin 8 exon 1 is a predictor for the plasma levels of IP-10 in MMT patients with urine test positive for morphine.

Diversity-Oriented Synthesis of Coumarin-Linked Benzimidazoles via a One-Pot, Three-Step, Intramolecular Knoevenagel Cyclization

Diversity-oriented synthesis of coumarin-linked benzimidazoles from N-(2-aminophenyl)-2-cyanoacetamide was achieved via a one-pot, three-step sequential reaction in excellent yields. In situ intramolecular cyclization of the cyanoacetamide afforded benzimidazoles which subsequently underwent a Knoevenagel condensation of the 2-cyanomethylbenzimidazoles with salicylaldehydes promoted by triethylamine to reach the target compounds. An important intermediate, 2-(2-imino-2H-chromen-3-yl)-1H-benzimidazole was characterized by X-ray analysis and further hydrolyzed to 2-(coumarin-3-yl)benzimidazole in acidic condition. Among the synthesized compounds, some were found to be promising inhibitors of porcine kidney d-amino acid oxidase (pkDAO).

Haplotypes of the D-Amino Acid Oxidase Gene Are Significantly Associated with Schizophrenia and Its Neurocognitive Deficits

D-amino acid oxidase (DAO) has been reported to be associated with schizophrenia. This study aimed to search for genetic variants associated with this gene. The genomic regions of all exons, highly conserved regions of introns, and promoters of this gene were sequenced. Potentially meaningful single-nucleotide polymorphisms (SNPs) obtained from direct sequencing were selected for genotyping in 600 controls and 912 patients with schizophrenia and in a replicated sample consisting of 388 patients with schizophrenia. Genetic associations were examined using single-locus and haplotype association analyses. In single-locus analyses, the frequency of the C allele of a novel SNP rs55944529 located at intron 8 was found to be significantly higher in the original large patient sample (p = 0.016). This allele was associated with a higher level of DAO mRNA expression in the Epstein-Barr virus-transformed lymphocytes. The haplotype distribution of a haplotype block composed of rs11114083-rs2070586-rs2070587-rs55944529 across intron 1 and intron 8 was significantly different between the patients and controls and the haplotype frequencies of AAGC were significantly higher in patients, in both the original (corrected p < 0.0001) and replicated samples (corrected p = 0.0003). The CGTC haplotype was specifically associated with the subgroup with deficits in sustained attention and executive function and the AAGC haplotype was associated with the subgroup without such deficits. The DAO gene was a susceptibility gene for schizophrenia and the genomic region between intron 1 and intron 8 may harbor functional genetic variants, which may influence the mRNA expression of DAO and neurocognitive functions in schizophrenia.

Design, synthesis and diversification of natural product-inspired hydantoin-fused tetrahydroazepino indoles

A facile and efficient synthesis of novel oxo, thio and seleno hydantoin fused tetrahydroazepino [4,5-b]indoles was reported.

UGT2B7 genetic polymorphisms are associated with the withdrawal symptoms in methadone maintenance patients

AIM

To test whether the genetic polymorphisms within the gene encoding the UGT2B7 gene may have an impact on methadone treatment.

MATERIALS & METHODS

Twelve SNPs in UGT2B7 were selected. 366 methadone maintenance treatment patients in Taiwan were recruited and genotyped.

RESULTS

In a genotype recessive model, rs6600879, rs6600880, rs4554144, rs11940316, rs7438135, rs7662029, rs7668258, rs7439366, rs4292394 and rs6600893 showed significant associations with severity of withdrawal symptoms (permutation p < 0.002), pupil size (permutation p < 0.048) and tremor (permutation p < 0.008). Haplotypes of GATCAGCCGC and CTCTGATTCT were significantly associated with pupil size score and tremor score (p < 0.034).

CONCLUSION

These results suggest that SNPs of the UGT2B7 gene may play important roles in opiate withdrawal symptoms.

A centrifugal particle concentrator for use in inhalation toxicology

Epidemiologic studies have provided strong evidence that episodic exposure to ambient particulate matter is associated with increases in morbidity and mortality. These adverse effects have been demonstrated at concentrations far below the National Ambient Air Quality Standard (NAAQS), and thus, the biological plausibility of these effects has been questioned. For the purpose of exposing test animals to relevant and reproducible exposure concentrations of ambient particulate matter (PM), we have developed a simple and inexpensive concentrator system that can concentrate ambient particles 10-fold. A high-volume blower is used to deliver ambient air to the inlet manifold of a centrifugal concentrator and the entrained particles travel along a concentric annulus formed by a stationary solid outer cylinder and a porous inner cylinder rotating at high speed (up to 12,500 rpm). Suction applied at one end of the porous shaft causes the dispersion medium (air) to pass through the porous cylinder and into the shaft. Since the rotational velocity of airborne particles is comparable to that of the rotating cylinder near its surface, the particles move radially outward due to the centrifugal force, in addition to their motion laterally along the cylinder and inward due to the suction of air into the rotating porous cylinder. The particles reach their highest concentration near the outlet manifold, where they enter the exposure chamber under positive pressure ( approximately 0.4 cm H2O). Except for coarse particle loss due to impaction and diffusional loss of ultrafine particles in the concentrator, the increase in particle concentration is the ratio of the flow rates for the inlet air and the air delivered to the exposure chamber. We have used the centrifugal concentrator to deliver concentrated ambient urban PM to a nose-only exposure chamber and examined the concentrating effect across ambient particle sizes.

Deposition of charged particles on lung airways

The effect of a single electric charge on the efficiency with which ultrafine particles deposit in human airways has been investigated. When inhaled short-lived radon progeny are attached to electrically neutral particles their deposition efficiency is controlled by diffusion. But most ambient particles carry one, or a few, charges. We measured and compared the deposition (DE) of singly charged, charge-neutralized, and zero-charge 20-nm and 125-nm particles in hollow-cast models of human airways. These particle sizes were selected because they are about where modal peaks occur for the activity of the short-lived radon progeny in indoor air. For singly charged 20-nm particles deposition (+/- standard error) in the casts was 3.4 +/- 0.3 times that for charge neutralized aerosols and 5.3 +/- 0.3 times the amount deposited for zero-charged particles. Corresponding ratios for the 125-nm particles were 2.3 +/- 0.3 and 6.2 +/- 0.7. Since most ambient particles are charged this effect must be considered when models are used to predict dose from inhaled ultrafine particles.

Generation of stable test atmospheres of cocaine base and its pyrolyzate, methylecgonidine, and demonstration of their biological activity

Generating controlled test atmospheres of known chemical identity and airborne concentration upon demand is a significant technical obstacle that limits the scope and repeatability of studies of inhaled substances. We addressed this problem as applied to the generation of atmospheres that result from heating crack cocaine, which include both cocaine and its pyrolyzate methylecgonidine (MEG). A condensation aerosol generator was used to generate atmospheres comprised of monodisperse particles of cocaine, MEG, or mixtures of both that are of submicron size suitable for deposition in the alveolar region of primates. Compressed air seeded with nanometer-size sodium chloride particles was passed through a constant depth of molten cocaine or MEG in a bead bed, reheated, and condensed to an aerosol within an annulus of cold air. To achieve control of a mixture of both compounds, MEG was condensed onto cocaine particles in a separate coating step. On-line analytical instruments provided verification of airborne concentration, estimates of particle size, and dispersion as well as chemical identity. Specific airway conductance (SGaw), heart rate, and rectal and skin temperatures were measured in squirrel monkeys breathing atmospheres containing condensation aerosols of cocaine or MEG free base. SGaw was reduced after inhalation of either base, and both induced temperature and cardiovascular changes, demonstrating that the aerosols so generated had biological activity.

Methylecgonidine coats the crack particle

Crack is a form of cocaine base self-administered by smoking. When heated, it volatilizes and may partially pyrolyze to methylecgonidine (MEG). Upon cooling, a condensation aerosol forms. Heating cocaine base in model crack pipes produced particles of about 1 micron in diameter, regardless of the amount heated; however, MEG concentration increased from < or = 2% at 10 mg per heating to as much as 5% at 30 mg per heating. Methylecgonidine was < or = 1% of the recovered material when cocaine was vaporized off a heated wire coil, but the particles were larger (2-5 microns), and the distribution disperse. The vapor pressure of MEG was higher [log P(mm Hg) = 9.994 - 3530/T] than cocaine base, consistent with MEG coating the droplet during condensation, and with evaporation during aging or dilution. Disappearance of MEG from a chamber filled with crack smoke was a two-component process, one proceeding at the rate of cocaine particle removal, and the other at the desorption rate from other surfaces. Particle diameter influences the deposition site in the respiratory tract; thus, the likely different patterns of deposition in the respiratory tract of humans and animals of crack aerosols produced by different techniques warrant consideration, as they may influence our understanding of immediate and delayed sequelae of the inhalation of cocaine and its pyrolysis product, MEG.

Effect of flow rate on aerosol bolus penetration in a hollow canine lung airway cast

A cast of dog tracheobronchial airways, which is complete to airways of 1 mm in diameter, was used for experimental studies of the effect of flow rate on aerosol bolus penetration during a tidal breath. Aerosol boli of 35 cm3 were injected during a 1-L inhalation of air. The recoveries of aerosol particles in expired air were measured after various breathholding times. The results show that the penetration depth of an aerosol bolus increases with decreasing flow rate, especially for flow in transition from a flat profile to a parabolic profile.

Dispersion of aerosol particles in an airway cast of a dog

Aerosol bolus dispersion was measured in the first branching generations of a replicate hollow cast. The cast was made from a solid cast of a beagle-dog tracheobronchial tree. The dispersion was measured after penetration of boluses into different volumetric depths, with different particle sizes and flow rates into the cast. An enhanced flow rate led to a decreasing dispersion in the cast. Particle size up to about 4 microns has no significant effect on dispersion.

Effect of lung airway branching pattern and gas composition on particle deposition in bronchial airways: III. Experimental studies with radioactively tagged aerosol in human and canine lungs

Particle penetration into lung airways during normal respiration is affected by the exchange of inspired air and residual gas. In this study, particle penetration during the inspiratory phase was investigated using gamma-tagged monodisperse particles (0.70, 0.90, 0.96, and 1.44 microns) suspended in various carrier gases having a wide range of kinematic viscosity. A 40-mL bolus of tagged aerosol was drawn into excised human and dog lungs at the end of a tidal breath, followed by a long breathhold to allow for complete particle deposition by sedimentation. The lungs were then fixed, sectioned, and autoradiographed to determine tidal front locations. In human lungs, particles suspended in He-O2 penetrated deeper than particles suspended in air; particles penetrated least in SF6-O2. Dog lungs, which have more asymmetrical airway branching patterns than human lungs, had no significant particle penetration differences associated with carrier gas composition. It is concluded that particle penetration during the inspiratory phase is dependent on factors that determine flow profile development, such as branching pattern and the Reynolds number of the carrier gas. The bolus front at the end of an air inspiration extended into about 10% of human lung airways of 1 mm diameter, and into about 0.1% of 0.5-mm airways. It is concluded that rapid particle penetration to 1-mm airways during high-frequency oscillatory ventilation of lung casts is due to cumulative axial core transport during multiple breathing cycles. Similarly, the dispersion of an aerosol bolus from large airways to small airways during in vivo breathholding studies appears to be due to oscillatory flow created by the heartbeat.

A novel system for the in vitro exposure of pulmonary cells to acid sulfate aerosols

While ambient acid aerosols are considered a potential respiratory health hazard, the mechanism by which they induce responses in the lungs is not known. Attempts to ascertain these mechanisms using inhalation exposures are complicated by a number of technical difficulties, chief among which are neutralization of inhaled acids by endogenous ammonia and variations in deposition with inhaled particle size. To control for these variables, a novel in vitro exposure system allowing experimental evaluation of factors which influence biologic responses to acid sulfate particles was developed. The system consists of two subunits, a generation/delivery component and a cell exposure component. Sulfuric acid aerosols are generated by nebulizing dilute acid solutions. Particles larger than a specified size of interest (based upon the specific exposure conditions desired) are removed, and particles at the desired size and mass concentration are uniformly delivered onto a target cell monolayer. The system is capable of delivering acid particles larger than 0.7 micron (mass median diameter), yet at constant particle mass concentrations. This paper describes the design of the exposure system and its performance characteristics and presents initial results of some biological responses obtained using it. In conjunction with inhalation studies, this exposure system may provide additional insights into mechanisms by which acid aerosols adversely affect the respiratory tract and into the physical characteristics of acid particles which modulate toxicity.

Aerosol tracer study of gas convective transport to 0.1-cm airways by high-frequency ventilation in a human lung airway cast

A cast of human tracheobronchial airways, which is complete to airways less than 0.1 cm in diameter, was employed for experimental studies of gas convective transport by high-frequency ventilation (HFV). The cast was ventilated with gases of different kinematic viscosity (He, air, and SF6) and tidal volumes of 10-60 mL. The convective transport through the cast was followed by labeling the tidal volume with 0.5-micron aerosol particles. Such particles undergo little diffusion and have a short relaxation time and, therefore, can serve as tracers of stream flow. The time of arrival of particles transported to isolated peripheral segments of the cast during HFV was measured with an optical particle counter at various oscillatory tidal volumes and frequencies. Distally directed particle transport was found to be substantial in He and air, but weak in SF6. The extent of transport increased with increasing tidal volume. These results provide evidence for a distally directed axial flow during quasi-steady-state tidal breathing of lung airways over a wide range of frequency. This superimposed distal flow along the axial core is consistent with (1) the demonstrated efficacy of O2-CO2 exchange during HFV, and (2) concentrations of particles deposited on bifurcations of alveolar ducts as observed during normal breathing in small animal inhalation studies.