***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: UNLABELLED There are reports suggesting that sensitivity to and tolerance of both clinical and experimental pain differ among ethnic groups . We examined  self-rated pain score and morphine usage in 1034 women who underwent elective lower cesarian section ( LSCS ) for their deliveries . Data on pain scores and amount of total morphine use according to patient-controlled analgesia were collected every 4 hours . Overall , lowest pain scores were recorded 12 hours after surgery and highest at 24 hours .  Morphine consumption was highest within the first 4 hours and lowest between 12 and 16 hours . There were statistically significant ethnic group differences in pain scores ( P = 1.7 x 10(-7 ) ) and  morphine usage ( P = 2.8 x 10(-15 ) ) between ethnic groups , with Indians having the highest mean pain score and using the highest amount of morphine . The ethnic differences in pain score and morphine self-administration persisted after controlling for age , body mass index , and duration of operation . PERSPECTIVE Our findings of highly significant ethnic group difference in self-reported pain level and the amount of analgesia self-administered may have implication s on optimal management of acute postoperative pain . Inadequate management of pain after cesarian deliveries might affect the emotional well-being and physical recovery of patients and affect mother-child bonding BACKGROUND : Previous studies have generated controversial results regarding the influence of the genetic variations of & mgr;-opioid receptors on morphine analgesia and opioid-related side effects in the postoperative period . Few studies have been conducted attempting to assess the combined effects of variation within ≥2 genes in relation to morphine response . In this study , we investigated whether combined catechol-O-methyltransferase and & mgr;-opioid receptor polymorphisms contribute to the morphine response in postoperative analgesia . METHODS : One hundred two surgical patients were enrolled in this prospect i ve , observational study . All patients received general anesthesia  and were screened for & mgr;-opioid receptor polymorphism A118 G ( Asn40Asp ) and catechol-O-methyltransferase G1947A ( Val158Met ) polymorphism using a blood sample of DNA . Patient-controlled analgesia was provided postoperatively and morphine consumption was observed . Any pain at rest or side effects were measured with rating scales . RESULTS : The heterozygous patients with & mgr;-opioid receptor A118 G and catechol-O-methyltransferase G1947A mutation consumed significantly less morphine in the postanesthetic recovery room and 48 hours after surgery compared with homozygous patients of the A118 variant . Nausea and sedation scores were also significantly lower during all observed postoperative periods for heterozygous patients and only 2 patients ( 18 % ) from this group received antinausea treatment . CONCLUSION : This study has demonstrated the importance of the gene-gene approach in underst and ing the morphine response in patients after lower abdominal surgery . More studies are needed to characterize the combined effects of multiple genes and demographic as well as clinical variables in predicting the correct morphine dosage and corresponding opioid-related side effects In this prospect i ve , observational study we explored whether A118 G single nucleotide polymorphism in the human & mgr;-opioid receptor ( MOR ) gene could explain the inter-individual differences in opioid analgesic requirements in patients with acute postoperative pain and chronic pain . The frequency of the wild-type A118 MOR ( major ) and variant G118 MOR ( minor ) alleles in the subjects with chronic , noncancer pain ( n = 121 ) and opioid-naïve subjects with acute postoperative pain ( n = 101 ) , serving as the control group , were examined . The relationships among the A118 G MOR genotype , opioid requirements , and the numerical pain score were analyzed in both groups . The frequency of the minor allele was significantly lower in the subjects with chronic pain when compared with the group with acute postoperative pain ( 0.079 versus 0.158 ; P = 0.009 by & khgr;2 test ) . No statistically significant association was observed between the presence of A118 G MOR polymorphism and the average postoperative pain score or the doses of morphine used in the immediate postoperative period . In the high-quartile , opioid utilization , chronic pain patients , the homozygotic carriers of the major allele required significantly higher opioid dose than did the carriers of the minor allele . The results indicate that although the presence of the minor allele does not appear to affect  opioid analgesic use in acute postoperative pain , the minor allele is less common in chronic pain patients , especially in those requiring higher doses of opioid analgesics Background Although intravenous morphine titration is widely used to obtain rapid and complete postoperative pain relief , the relationship between measurement of pain and morphine requirements varies , and the evolution of pain during titration is poorly understood . Methods Intravenous morphine titration was administered as a bolus of 2 ( body weight ≤ 60 kg ) or 3 mg ( body weight > 60 kg ) during the immediate postoperative period in the PACU . The interval between each bolus was 5 min . The visual analog scale ( VAS ) score threshold required to administer morphine was 30 , and pain relief was defined as a VAS score of 30 or less . Results Data from 3,045 patients were analyzed .  The mean initial VAS score was 73 ± 19 ( mean ± SD ) , and the mean morphine dose required to obtain pain relief was 0.17 ± 0.10 mg/kg , i.e. , a median of four boluses ( range , 1–20 ) . When patients were grouped according to several classes of initial VAS score ( 31–39 , 40–49 , 50–59 , 60–69 , 70–79 , 80–89 , 90–100 ) , it seemed that the relationship between VAS score and morphine requirements was a sigmoid curve . A VAS score of 70 or greater predicted the need for a high ( > 0.15 mg/kg ) morphine dose ( sensitivity , 0.77 ; specificity , 0.54 ) . During the pain relief process , the relationship between VAS score and time was depicted by a sigmoid curve . Conclusion A VAS score of 70 or greater should be considered indicative of severe pain . The relationship between the initial VAS score and morphine requirements is not linear , and the evolution of the VAS score during the pain relief process is described by a sigmoid curve Purpose To investigate interindividual variability in response to pain treatment , we characterized postoperative patients for morphine metabolism and for COMT , OPRM1 and UGT2B7 polymorphisms . Methods A total of 109 patients treated with morphine  were genotyped by DNA sequencing for 12 DNA polymorphisms of the COMT , OPRM1 and UGT2B7 genes . The plasma concentration of morphine and of M3G/M6 G metabolites were evaluated by means of reversed phase high-performance liquid chromatography coupled with mass spectrometry . Results An association between average morphine consumption during the first 24 postoperative hours by patient-controlled analgesia ( PCA ) and COMT haplotypes was found . Specifically , patients with the diplotype for average pain intensity ( APS/APS ) required the lowest  morphine doses compared to the other subjects ( p = 0.011 ) . The APS haplotype contains an adenine corresponding to methionine , instead of valine , at position 158 of the COMT protein . Met/Met homozygous patients consumed significantly lower morphine doses than other subjects ( p = 0.014 ) ; accordingly , Val158Met genotyping alone might be used in the clinical setting to predict PCA morphine need . Considering both COMT Val158Met and OPRM1 A118 G polymorphisms , carriers of both the Met/Met and AA genotypes required less morphine than other subjects , although the difference was not significant . The analysis of UGT2B7 revealed the occurrence of two common haplotypes ( G_C_C_A_C and A_T_T_G_T ) that did not prove to be related with plasma morphine and M3G/M6 G concentration . Conclusions By considering COMT , OPRM1 , and UGT2B7 genotypes , as well as pharmacokinetic results , only COMT polymorphisms appear to be predictive of morphine need in postoperative pain therapy Abstract Visceral pain can be difficult to treat with classical & mgr;‐opioid agonists and it has been suggested to use opioids with distinct pharmacological profiles . In animal experiments , oxycodone has shown different effects compared to morphine , and clinical observations have shown that oxycodone may occasionally be superior to , e.g. , morphine in the treatment of visceral pain . In the current study , we r and omised 24 healthy subjects to treatment with either morphine ( 30 mg ) , oxycodone ( 15 mg ) or placebo in a crossover study . The experimental pain model involved multi‐modal ( mechanical , thermal and electrical ) pain tests in the skin , muscles and viscera . The pain tests were carried out at baseline and 30 , 60 and 90 min after oral administration of the drugs . The model showed effect of the two opioids compared to placebo on all stimulus modalities in all three types of tissues ( all P values < 0.001 ) . Both opioids attenuated the sensory response mainly to painful stimulations . Morphine and oxycodone were equipotent in pain modulation of the skin and muscles , but oxycodone had superior analgesic effect to both morphine and placebo on the mechanical ( P < 0.001 ) and thermal ( P < 0.001 ) stimulations of the oesophagus . In conclusion , the multi‐modal and tissue‐differentiated pain model could link findings from animal experiments to clinical findings . A different pharmacological profile of oxycodone compared to that of morphine was shown , and thus oxycodone may be a useful alternative to morphine in the treatment of visceral pain syndromes OBJECTIVE Fentanyl , a μ-opioid receptor agonist , is a substrate of P-glycoprotein . Its metabolism is catalyzed by CYP3A4 and CYP3A5 . The aim of this study was to investigate the association between postoperative fentanyl consumption and genetic polymorphisms of μ-opioid receptor ( OPRM1 ) , ABCB1 ( gene encoding P-glycoprotein ) , CYP3A4 and CYP3A5 in Korean patients . METHODS 196 female patients scheduled to undergo total abdominal hysterectomy or laparoscopic assisted vaginal hysterectomy under general anesthesia were enrolled in this study . Intravenous patient-controlled analgesia with fentanyl was provided postoperatively . Cumulative fentanyl consumption was measured during the first 48 hours postoperatively . The severity of pain at rest was assessed with the visual analogue scale . OPRM1 118A > G , ABCB1 2677G > A/T , ABCB1 3435C > T , CYP3A4 * 18 and CYP3A5 * 3 variant alleles were genotyped . The effects of genetic and non-genetic factors on fentanyl requirements were evaluated with multiple linear regression analysis . RESULTS The 24-hour cumulative fentanyl doses were significantly associated with pain core , weight and type of surgery ( p < 0.05 ) . The 48-hour cumulative fentanyl doses were significantly associated with pain score , type of surgery and history of PONV or motion sickness ( p < 0.05 ) . Genetic polymorphisms were not associated with fentanyl requirements . CONCLUSION In Korean gynecologic patients , no association was found between genetic factors and postoperative fentanyl consumption Background : Animal and human studies indicate that genetics may contribute to the variability of morphine efficacy . A recent report suggested that cancer patients homozygous for the 118 G allele caused by the single nucleotide polymorphism at nucleotide position 118 in the & mgr;-opioid receptor gene require higher doses of morphine to relieve pain . The purpose of the current study was to investigate whether this polymorphism contributes to the variability of morphine efficacy in women who undergo abdominal total hysterectomy . Methods : After informed consent was obtained , 80 female patients ( American Society of Anesthesiologist physical status I or II ) scheduled to undergo elective total hysterectomy surgery were enrolled in this study . All patients received general anesthesia  and were screened for A118 G polymorphism by blood sample . Intravenous morphine patient-controlled analgesia was provided postoperatively for satisfactory analgesia . The authors recorded the  morphine consumption doses and dem and times . Pain at rest and side effects were measured with rating scales . Results : Forty-three women were A118 homozygous , 19 were heterozygous , and 18 were G118 homozygous . Patients homozygous for G118 required more morphine doses ( 33 ± 10 mg ) to achieve adequate pain relief compared with patients homozygous for A118 ( 27 ± 10 mg ) in the first 24 h ( P = 0.02 ) . However , there was no statistically significant difference for morphine consumption at 48 h. Conclusion : Genetic variation of the & mgr;-opioid receptor may contribute to interindividual differences in postoperative morphine consumption . In the future , identifying single nucleotide polymorphisms of patients may provide information to modulate the analgesic dosage of opioid for better pain control 
    Output:
    
The OPRM1 A118 G polymorphism was associated with interindividual variability in postoperative response to opioids .
In a sub population , identifying OPRM1 A118 G polymorphism may provide valuable information regarding the individual analgesic doses that are required to achieve satisfactory pain control