Development of the Handy Bio-Strand and its application to genotyping of OPRM1 (A118G)

Genetic susceptibility to postherniotomy pain. The influence of polymorphisms in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes

BACKGROUND AND AIMS

Despite improvements in surgical technique, 5%-8% of patients undergoing herniorrhaphy still suffer from clinically relevant persistent postherniotomy pain. This is a problem at both individual and society levels. The aim of this study was to determine whether or not a single nucleotide polymorphism in a specific gene contributes to the development of persistent pain after surgery.

METHODS

One hundred individuals with persistent postherniotomy pain, along with 100 without pain matched for age, gender and type of surgery were identified in a previous cohort study on patients operated for groin hernia. All patients underwent a thorough sensory examination and blood samples were collected. DNA was extracted and analysed for single nucleotide polymorphism in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes.

RESULTS

Patients with neuropathic pain were found to have a homozygous single nucleotide polymorph in the TNF-α gene significantly more often than pain-free patients (P=0.036, one-tailed test).

CONCLUSIONS

SNP in the TNF-α gene has a significant impact on the risk for developing PPSP.

IMPLICATIONS

The result suggests the involvement of genetic variance in the development of pain and this requires further investigation.

Depressed mood, anxiety, and the use of labor analgesia

Relatively little is known about mental health and labor pain. The aim of this study was to assess if self-rated antenatal depressed mood and anxiety are associated with pain-related behaviors and self-reported labor pain. We also wanted to replicate our previous finding of altered labor pain behavior in carriers of a specific guanosine triphosphate cyclohydrolase 1 gene (GCH1) haplotype. Ninety-nine women in gestational weeks 37 to 40 filled out questionnaires on depression and anxiety symptoms and later rated their labor pain by use of visual analog scales. Each subject was also genotyped for GCH1. Following adjustment for relevant confounders, women who arrived early to the delivery unit (cervical dilation <5 cm) had a significantly higher antenatal Montgomery-Åsberg Depression Rating Scale (MADRS-S) score, p < 0.05, than late arrivers (cervical dilation >5 cm). Women with increased Spielberger State-Trait Anxiety Inventory (STAI-T) scores reported higher self-rated pain prior to labor analgesia, p < 0.05, than women with low STAI-T scores. No association between the GCH1 pain-protective haplotype and cervical dilation was found, but a previously demonstrated association with increased use of second-line analgesia was confirmed. Depressed mood during pregnancy is associated with early arrival to the delivery department, whereas antenatal anxiety is associated with increased self-rated pain prior to labor analgesia.

Combined analysis of circulating β-endorphin with gene polymorphisms in OPRM1, CACNAD2 and ABCB1 reveals correlation with pain, opioid sensitivity and opioid-related side effects

Background

Opioids are associated with wide inter-individual variability in the analgesic response and a narrow therapeutic index. This may be partly explained by the presence of single nucleotide polymorphisms (SNPs) in genes encoding molecular entities involved in opioid metabolism and receptor activation. This paper describes the investigation of SNPs in three genes that have a functional impact on the opioid response: OPRM1, which codes for the μ-opioid receptor; ABCB1 for the ATP-binding cassette B1 transporter enzyme; and the calcium channel complex subunit CACNA2D2. The genotyping was combined with an analysis of plasma levels of the opioid peptide β-endorphin in 80 well-defined patients with chronic low back pain scheduled for spinal fusion surgery, and with differential sensitivity to the opioid analgesic remifentanil. This patient group was compared with 56 healthy controls.

Results

The plasma β-endorphin levels were significantly higher in controls than in pain patients.

A higher incidence of opioid-related side effects and sex differences was found in patients with the minor allele of the ABCB1 gene. Further, a correlation between increased opioid sensitivity and the major CACNA2D2 allele was confirmed. A tendency of a relationship between opioid sensitivity and the minor allele of OPRM1 was also found.

Conclusions

Although the sample cohort in this study was limited to 80 patients it appears that it was possible to observe significant correlations between polymorphism in relevant genes and various items related to pain sensitivity and opioid response. Of particular interest is the new finding of a correlation between increased opioid sensitivity and the major CACNA2D2 allele. These observations may open for improved strategies in the clinical treatment of chronic pain with opioids.

Different SNP combinations in the GCH1 gene and use of labor analgesia

Background

The aim of this study was to investigate if there is an association between different SNP combinations in the guanosine triphosphate cyclohydrolase (GCH1) gene and a number of pain behavior related outcomes during labor. A population-based sample of pregnant women (n = 814) was recruited at gestational week 18. A plasma sample was collected from each subject. Genotyping was performed and three single nucleotide polymorphisms (SNP) previously defined as a pain-protective SNP combination of GCH1 were used.

Results

Homozygous carriers of the pain-protective SNP combination of GCH1 arrived to the delivery ward with a more advanced stage of cervical dilation compared to heterozygous carriers and non-carriers. However, homozygous carriers more often used second line labor analgesia compared to the others.

Conclusion

The pain-protective SNP combination of GCH1 may be of importance in the limited number of homozygous carriers during the initial dilation of cervix but upon arrival at the delivery unit these women are more inclined to use second line labor analgesia.

Semi-quantitative discrimination of HBV mutants using allele-specific oligonucleotide hybridization with Handy Bio-Strand

The analysis of hepatitis B virus (HBV) mutations is important for understanding HBV progression and for deciding on appropriate clinical treatments. However, it is difficult to determine the quantitative abundance of various mutants in heterogeneous mixtures by conventional methods such as direct sequencing or the TaqMan assay. In this study, we investigated the possibility of using both allele-specific oligonucleotide hybridization (ASOH) and allele-specific oligonucleotide competitive hybridization (ASOCH) with the Handy Bio-Strand system for the quantitative identification of three well-defined HBV variants: the basal core promoter (BCP) mutations (nt1762 and nt1764), the pre-core (PC) mutation (nt1896), and variance at nt1858. Using standardized mixtures of wild-type and mutant DNA, optimal hybridization conditions for ASOH and ASOCH were determined. Next, the performance of these methods was evaluated using actual serum DNAs from HBV patients. Excellent reproducibility was obtained both in the analysis of internal positive controls and in the semi-quantitative categorization of heterogeneous viral mixtures into five abundance groups (0%, 25%, 50%, 75%, and 100% mutant virus). Combined with real-time PCR to determine the HBV viral load, this hybridization method offers a new tool with applications both in HBV clinical research and treatment.

Endogenous opiates and behavior: 2007

This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.