Relationship between chlordane and its metabolites in blood of pest control operators and spraying conditions

Chlordane has been widely used to protect soil and house foundations against termite infestation. Pest control operators (PCOs) are occupationally exposed to chlordane. The relationship between chlordane and its metabolites in blood of PCOs and spraying conditions were investigated. Chlordane and its metabolites were detected in the blood of some chlordane-exposed PCOs, but not in that of the controls. Trans-nonachlor and the metabolites oxychlordane and heptachlor epoxide were detected in the blood of PCOs. Total concentration of chlordane and its metabolites in blood (trans-nonachlor + oxychlordane + heptachlor epoxide) was less than 5.6 ppb (mean: 0.89 ppb). The concentration of chlordane and its metabolites in blood of chlordane-exposed PCOs was significantly correlated with the number of spraying days and the amount of chlordane sprayed, particularly with a large correlation coefficient (r = 0.81, P less than 0.001) with the spraying days in the three months prior to the medical examination. The concentration of chlordane and its metabolites in blood is considered to be a useful indicator of biological monitoring for chlordane exposed workers (PCOs).

Association between averaged intraoperative nociceptive response index and postoperative complications after lung resection surgery

OBJECTIVES

Since postoperative complications, defined as Clavien-Dindo grade ≥II, correlate with long-term survival after lung resection surgery in patients with primary lung cancer, identification of intraoperative risk factors for postoperative complications is crucial for better perioperative management. In the present study, we investigated the possible association between intraoperative variables for use in anaesthetic management and Clavien-Dindo grade ≥II.

METHODS

In this multi-institutional observational study, consecutive adult patients undergoing video-assisted thoracic surgery for primary lung cancer under general anaesthesia from March 2019 to April 2021 were enrolled. All patients were divided into 2 groups with Clavien-Dindo grade <II and ≥II. Uni- and multivariable analyses were performed to identify intraoperative risk factors.

RESULTS

After univariable analysis between patients with Clavien-Dindo grade <II (n = 415) and ≥II (n = 121), multivariable analysis revealed higher averaged nociceptive response (NR) index during surgery (mean NR), male sex, lower body mass index, longer duration of surgery, higher blood loss and lower urine volume, as independent risk factors for postoperative complications. In sensitivity analysis, based on the cut-off value of mean NR for postoperative complications, all patients were divided into high and low mean NR groups. The incidence of postoperative complications was significantly higher in patients with high mean NR (n = 332) than in patients with low mean NR (n = 204; P < 0.001).

CONCLUSIONS

Higher mean NR, as intraoperative variables for use in anaesthetic management, is associated with the higher incidence of postoperative complications after primary lung cancer surgery.

[Lead exposure of workers in the ceramics industry and relevant factors]

To clarify lead exposure and factors relevant to it, an occupational health survey and air lead-concentration survey were conducted among 425 workers in the ceramics industry in the Seto region in Aichi Prefecture. As for biological monitoring, blood lead level was measured according to sex, job, product, factory size and duration of lead exposure. The following major findings were obtained in the present analysis. Workers making dolomite novelties showed higher blood lead levels than those making porcelain novelties, semi-porcelain novelties and tableware. The difference in blood lead level by job was statistically significant, but not that by factory size. In males, the highest blood lead level was found for spray painting work (28.7 micrograms/dl), followed by glazing work (28.0 micrograms/dl), kiln work (23.3 micrograms/dl) and painting work (22.3 micrograms/dl). In females, the blood lead level for painting work (13.5 micrograms/dl) was lower than those for glazing work (26.1 micrograms/dl) and kiln work (31.4 micrograms/dl). The blood lead level was significantly increased with the number of years of lead exposure in females (painting work). It was coincidentally clarified that the environmental lead concentration varied according to the job in which workers were engaged. As protective measures against lead exposure for workers in the ceramics industry, the development of nonlead paint and glaze and the introduction of more effective dust collectors at the workplace should be established.

The temporal expression of circulating microRNAs after acute experimental pain in humans

BACKGROUND

MicroRNAs (miRNAs) can modulate several biological systems, including the pain system. This study aimed to evaluate the temporal expression of circulating miRNAs in the plasma of healthy volunteers as a marker for epigenetic changes before and after an acute, experimental, pain provocation by intramuscular hypertonic saline injection.

METHODS

Twenty volunteers were randomly allocated into two groups and received either hypertonic (pain) or isotonic (control) saline injection in the first dorsal interosseous muscle of their dominant hand. Pain intensity was continuously recorded for 20 minutes after injection on a VAS scale from 0 to 100 (0 indicates no pain and 100 the worst imaginable pain). Blood samples were taken at baseline, 30 minutes, 3 hours, and 24 hours post-injection, and plasma was separated. MiRNA extracts were used for RNA sequencing with the Illumina NextSeq platform. MiRNA transcripts were compared between the pain and the no-pain, control group at every time point. Significant differences were considered when folds were >2 and the False Discovery Rate was p < 0.05.

RESULTS

After 30 minutes, 4 miRNAs were significantly altered in the pain group compared to controls, which increased to 24 after 3 hours and to 42 after 24 hours from baseline (p < 0.0001). Two miRNAs were consistently upregulated throughout the experiment. Enrichment analysis showed significant miRNAs involved in brain perception of pain, brain signalling and response to stimuli.

CONCLUSIONS

This exploratory study is the first to report on the temporal expression of circulating miRNAs after an acute, human experimental muscle pain model.

SIGNIFICANCE

This exploratory study evaluated the temporal profile of circulating miRNAs in the plasma of healthy subjects after acute experimental pain. Several miRNAs were altered in subjects at the times of follow-up after the acute pain model when compared to controls. MiRNAs previously associated with pain processes were altered in the pain group. Our results, by showing the fast and prolonged modifications of miRNA elicited by the acute experimental pain model, add new perspectives to the topic of epigenetics and pain.

Effects of Simulation Study of High Neuraxial Block During Epidural Analgesia for Labor Pain on Pre/Posttest Evaluation in Junior Clinical Trainees

Background

Since a high neuraxial block is one of the serious complications in obstetric anesthesia, simulation training is required for the education of rapid diagnosis and treatment of this complication.

Objectives

This study aimed to evaluate the effects of a simulation study of the high neuraxial block during epidural analgesia for labor pain on pre- and post-simulation tests in junior clinical trainees, who had graduated a medical school within one or two years and being under a two-month program for anesthesia during the Japanese Postgraduate Medical Education.

Methods

Twenty-two junior clinical trainees participated in this study from September 2016 to May 2017. Before the simulation training, the participants answered a pretest, providing written responses on “how to approach and treat the rapid spread of anesthesia (high neuraxial block) in painless epidural delivery” in a bullet-point form. The number of correct answers to 12 items was counted for each participant. These items were as follows: mask ventilation, preparation for tracheal intubation, oxygenation, supraglottic airway placement, checking the breathing, checking oxygen saturation using pulse oximetry, checking blood pressure, ephedrine injection, checking epidural tube, assessing the level of sensory block, assessing the level of consciousness, and left uterine displacement. After performing our original training, all participants were debriefed and written responses were obtained to a posttest containing the same content as the pretest.

Results

The percentage of correct answers significantly increased from 8.3 to 16.7% (P = 0.041) after training. The response rates for “mask ventilation” and “check epidural tube” significantly increased from 13.6 to 54.5% (P = 0.004) and from 4.5 to 27.3% (P = 0.039), respectively, after training.

Conclusions

Simulation training is likely an effective method for junior clinical trainees on studying diagnosis and treatment of high neuraxial block during epidural analgesia in parturient patients.

The Impact of Nociception Monitor-Guided Multimodal General Anesthesia on Postoperative Outcomes in Patients Undergoing Laparoscopic Bowel Surgery: A Randomized Controlled Trial

BACKGROUND

Excess surgical stress responses, caused by heightened nociception, can lead to elevated levels of postoperative inflammation, resulting in an increased incidence of complications after surgery. We hypothesized that utilizing nociception monitor-guided multimodal general anesthesia would exert effects on postoperative outcomes (e.g., serum concentrations of C-reactive protein (CRP) after surgery, postoperative complications).

METHODS

This single-center, double-blinded, randomized trial enrolled ASA class I/II adult patients with normal preoperative CRP levels, scheduled for laparoscopic bowel surgery. Patients were randomized to receive either standard care (control group) or nociception monitor-guided multimodal general anesthesia using the nociceptive response (NR) index (NR group), where NR index was kept below 0.85 as possible. The co-primary endpoint was serum concentrations of CRP after surgery or rates of 30-day postoperative complications (defined as Clavien-Dindo grades ≥ II).

MAIN RESULTS

One hundred and four patients (control group, n = 52; NR group, n = 52) were enrolled for analysis. The serum CRP level on postoperative day (POD) 1 was significantly lower in the NR group (2.70 mg·dL-1 [95% confidence interval (CI), 2.19-3.20]) than in the control group (3.66 mg·dL-1 [95% CI, 2.98-4.34], p = 0.024). The postoperative complication rate was also significantly lower in the NR group (11.5% [95% CI, 5.4-23.0]) than in the control group (38.5% [95% CI, 26.5-52.0], p = 0.002).

CONCLUSIONS

Nociception monitor-guided multimodal general anesthesia, which suppressed intraoperative nociception, mitigated serum concentrations of CRP level, and decreased postoperative complications after laparoscopic bowel surgery.

Painful myokymia after surgery in a patient with Isaacs' syndrome: a case report

Background

Isaacs’ syndrome is a peripheral nerve hyperexcitability syndrome and rare acquired channel disease. The symptoms (myokymia, neuromyotonia, and muscle spasm) emerge even during sleep. This report describes the anesthetic management, especially neuromuscular blocking drugs and postoperative pain, in a case of Isaacs’ syndrome.

Case presentation

A 63-year-old woman with Isaacs’ syndrome underwent elective laparoscopic distal gastrectomy under general anesthesia without epidural anesthesia. She received double filtration plasmapheresis four times to alleviate symptoms before surgery. To avoid a prolonged neuromuscular blockade, we performed total intravenous anesthesia and titrated muscle relaxant with neuromuscular monitoring. Anesthetic management was performed without any problems. However, pain management after surgery proved difficult as she experienced severe pain due to myokymia.

Conclusions

Despite attempts to minimize symptoms, severe postoperative pain associated with myokymia occurred. Continuous regional anesthesia should be considered to treat pain from abnormal discharge in the central nervous system in Isaacs’ syndrome.

Age-related changes in intraoperative mean values of nociceptive response in patients undergoing non-cardiac surgery under general anesthesia: A retrospective cohort study

Intraoperative nociception is affected by preoperative factors, surgical invasiveness, and anesthesia. Although age-related changes in nociception in conscious humans have been well examined, those in intraoperative nociception in unconscious patients under general anesthesia are unknown. To clarify associations between age and intraoperative nociception under general anesthesia, we performed a retrospective cohort study in consecutive patients of all ages undergoing non-cardiac surgery under general anesthesia from January 2019 to July 2023. The intraoperative nociception value in each surgery was assessed by the averaged value of nociceptive response (mean NR) index during surgery. Patient characteristics, including age, sex, body mass index (BMI), emergent surgery, preoperative serum C-reactive protein (CRP) level, and comorbidities were also collected. After excluding patients with missing data of CRP and mean NR index, 22,061 patients were enrolled, and were divided into low, intermediate, and high surgical risk groups. Multivariable regression analysis showed a significant association between age and mean NR index in all three surgical procedure risk groups. The preoperative variables of CRP levels, BMI, emergent surgery, atrial fibrillation, renal failure, and long-term steroid use also showed significant associations with mean NR index in all three groups. Sensitivity analysis showed that intraoperative mean NR index was higher in younger children than that in both older children and younger adults, and it gradually increased again in older adults to the same level as in younger children. In conclusion, there is likely an association between age and intraoperative mean NR index in patients under general anesthesia.

Association between thoracic epidural block and major complications after pleurectomy/decortication for malignant pleural mesothelioma under general anesthesia

Introduction

A curative-intent surgical procedure, pleurectomy/decortication, for malignant pleural mesothelioma is accompanied by a high incidence of major postoperative complications. Although epidural block, which suppresses nociception during and after surgery, reportedly has both benefits and disadvantages in terms of outcomes after thoracic surgery for other diseases, the effects of epidural block on major complications after pleurectomy/decortication have not been evaluated. The aim of this study was to evaluate the association between epidural block and major postoperative complications following pleurectomy/decortication.

Methods

In a single-institutional observational study, consecutive adult patients undergoing pleurectomy/decortication under general anesthesia were enrolled from March 2019 to December 2021. Multivariable logistic regression analysis was performed to determine the association between perioperative variables and major complications. Next, patients were divided into two groups: general anesthesia with and without epidural block. Incidences of major postoperative complications, defined as Clavien-Dindo grades≥III, were compared between groups.

Results

In all patients enrolled with American Society of Anesthesiologists (ASA) physical status II or III (n=99), general anesthesia without epidural block was identified as a sole risk factor for major complications among perioperative variables. The incidence of major complications was 32.3% (95% CI 19.1% to 49.2%) in patients with epidural block (n=34), which was significantly lower than 63.1% (95% CI 50.9% to 73.8%) in patients without epidural block (n=65). In sensitivity analysis in patients with ASA physical status II alone, the same results were obtained.

Conclusion

Epidural block is likely associated with reduction of the incidence of major complications after pleurectomy/decortication for malignant pleural mesothelioma under general anesthesia.

Asystole developed during total gastrectomy under general anesthesia combined with thoracic epidural anesthesia

We report a 73-year-old woman who developed sudden bradycardia and asystole due to vagal reflex during transabdominal total gastrectomy under general anesthesia with thoracic epidural analgesia. General anesthesia was induced with propofol, fentanyl and maintained with sevoflurane and epidural infusion of lidocaine. Severe bradycardia, followed by asystole was detected on electrocardiography 10 minutes after starting surgery, triggered by the retraction of the abdominal wall and intestines. Blood pressure and heart rate recovered in response to atropine, ephedrine and chest compressions in 10 seconds. Surgery was completed uneventfully and the patient was discharged without complications. For preventing life-threatening bradycardia and asystole by vagal reflex, we suggest the use of atropine prior to the operations in patients undergoing abdominal or ophthalmic surgery, where vagal reflex may occur.

Intraoperative nociception and postoperative inflammation associated with the suppression of major complications due to thoracic epidural block after pleurectomy/decortication for malignant pleural mesothelioma under general anesthesia: A retrospective observational study

A recent study showed that thoracic epidural block (TEB) suppressed the occurrence of major complications after pleurectomy/decortication (P/D) for malignant pleural mesothelioma (MPM) under general anesthesia. To investigate the mechanisms underlying the correlation, both acute inflammatory status and intraoperative nociception were evaluated in the present study. In a single-institutional observational study, consecutive adult patients undergoing P/D were enrolled from March 2019 to April 2022. Perioperative acute inflammatory status was evaluated using differential White blood cell (WBC) counts and serum concentration of C-reactive protein (CRP) both before and after the surgery on postoperative day (POD) 1. The averaged value of nociceptive response index during surgery (mean NR) was obtained to evaluate the level of intraoperative nociception. Multivariable logistic regression analysis was performed to determine the association between perioperative variables and major complications Postoperative major postoperative complication was defined as Clavien-Dindo grades ≥ III. We conducted this study with 97 patients. After logistic regression analysis showed that general anesthesia without TEB was a sole risk factor for major complications, patients were divided into 2 groups: general anesthesia with and without TEB. The incidence of major complications was significantly lower in patients with TEB (33.3%, n = 33) than in those without TEB (64.1%, n = 64, P < .01). Although there was no significant difference in the CRP level between 2 groups, the lymphocyte-to-monocyte ratio (LMR) on POD 1 in patients with TEB was significantly higher than that in patients without TEB (P = .04). The mean NR was significantly lower in patients with TEB than that in those without TEB (P = .02). Both lower mean NR during surgery and higher LMR on POD 1 are likely associated the suppression of major complications due to TEB after P/D under general anesthesia. Decreases in the postoperative acute inflammatory response, caused by the reduction of intraoperative nociception due to TEB, may help suppress major complications after P/D.

Mechanisms and treatment of opioid-induced pruritus: Peripheral and central pathways

BACKGROUND AND OBJECTIVE

Pruritus (also known as itch) is defined as an unpleasant and irritating sensation of the skin that provokes an urge to scratch or rub. It is well known that opioid administration can cause pruritus, which is paradoxical as itch and pain share overlapping sensory pathways. Because opioids inhibit pain but can cause itching. Significant progress has been made to improve our understanding of the fundamental neurobiology of itch; however, much remains unknown about the mechanisms of opioid-induced pruritus. The prevention and treatment of opioid-induced pruritus remains a challenge in the field of pain management. The objective of this narrative review is to present and discuss the current body of literature and summarize the current understanding of the mechanisms underlying opioid-induced pruritus, and its relationship to analgesia, and possible treatment options.

RESULTS

The incidence of opioid-induced pruritus differs with different opioids and routes of administration, and the various mechanisms can be broadly divided into peripheral and central. Especially central mechanisms are intricate, even at the level of the spinal dorsal horn. There is evidence that opioid receptor antagonists and mixed agonist and antagonists, especially μ-opioid antagonists and κ-opioid agonists, are effective in relieving opioid-induced pruritus. Various treatments have been used for opioid-induced pruritus; however, most of them are controversial and have conflicting results.

CONCLUSION

The use of a multimodal analgesic treatment regimen combined with a mixed antagonist and κ agonists, especially μ-opioid antagonists, and κ-opioid agonists, seems to be the current best treatment modality for the management of opioid-induced pruritus and pain.

SIGNIFICANCE

Opioids remain the gold standard for the treatment of moderate to severe acute pain as well as cancer pain. It is well known that opioid-induced pruritus often does not respond to regular antipruritic treatment, thereby posing a challenge to clinicians in the field of pain management. We believe that our review makes a significant contribution to the literature, as studies on the mechanisms of opioid-induced pruritus and effective management strategies are crucial for the management of these patients.

Associations between intraoperative nociceptive response index and early postoperative acute kidney injury in patients undergoing non-cardiac surgery under general anesthesia: a single-center retrospective cohort study

Both tissue hypoperfusion and elevated surgical stress during surgery are involved in the pathogenesis of postoperative acute kidney injury (AKI). Although intraoperative hypotension, which evokes renal hypoperfusion, has been reported to be associated with the development of postoperative AKI, there is no consensus on the association between surgical stress responses (e.g., hypertension and inflammation) and postoperative AKI. Given that intraoperative values of nociceptive response (NR) index are reportedly associated with surgical stress responses, the present study was performed to assess associations between intraoperative NR index and postoperative AKI in patients undergoing non-cardiac surgery. In this single-institutional retrospective cohort study, data of the highest and lowest values of NR index during surgery were obtained in consecutive adult patients undergoing non-cardiac surgery under general anesthesia from February 2022 to August 2023. Data on highest and lowest mean blood pressure (MBP) during surgery were also obtained. In 5,765 patients enrolled, multivariate regression analysis revealed that the development of early postoperative AKI was significantly associated with highest NR during surgery ≥ 0.920, lowest MBP during surgery < 54 mmHg, age ≥ 48 years, male sex, ASA-PS ≥ III, emergency, and duration of surgery ≥ 226 min. In addition to intraoperative hypotension, a higher level of intraoperative NR index is likely associated with higher incidence of early postoperative AKI in adult patients undergoing non-cardiac surgery under general anesthesia.

[Anesthetic Management of a Parturient with Eclampsia, Posterior Reversible Encephalopathy Syndrome and Pulmonary Edema due to Pregnancy-induced Hypertension]

A 27-year-old woman with mental retardation was admitted to a nearby hospital for an abrupt onset of seizure. Physical examination revealed remarkable hypertension and pregnancy with estimated gestational age of 28th week. Severe pulmonary edema and hypoxia led to a diagnosis of pregnancy-induced hypertension (PIH) accompanied by eclampsia. She was orotracheally intubated because of refractory seizure and hypoxemia, and transferred to our hospital for further treatment. Besides severe hypoxia and hypercapnea, an enhanced lesion was detected in the left posterior cerebrum by brain MRI. No abnormal findings were detected in the fetus, with heart rate of 150 beats x min. She was diagnosed with posterior reversible encephalopathy syndrome (PRES) caused by PIH and emergency cesarean section under general anesthesia was scheduled. A male newborn was delivered with Apgar score of 1/4 (1/5 min), followed by starting continuous infusion of nicardipine for controlling hypertension. Chest X-P on completion of surgery revealed remarkably alleviated pulmonary edema. She received intensive treatment and continued positive pressure ventilation for four days after delivery. She recovered with no neurological deficits and her child was well without any complications.

Postoperative Analgesia and Length of Hospital Stay After Surgery for Malignant Pleural Mesothelioma: A Retrospective Observational Study

Background

Pleurectomy/decortication (P/D), a surgical procedure for malignant pleural mesothelioma (MPM), is a highly invasive surgery requiring prolonged hospitalization. Previous studies have reported that postoperative analgesia using regional anesthesia contributes to shorter hospital stays after surgery under general anesthesia by reducing acute postoperative pain. However, the association between postoperative analgesia and the length of hospital stay (LOHS) following P/D has not been evaluated.

Objectives

To evaluate the association between postoperative analgesia and postoperative LOHS after P/D.

Methods

This single-institution observational study enrolled consecutive adult patients undergoing P/D under general anesthesia, who postoperatively received either intertransverse process block (ITPB) or continuous intravenous (IV) fentanyl infusion as postoperative analgesia between March 2022 and February 2023.

Results

Among all enrolled patients with ASA physical status II or III (n = 60), postoperative analgesia was administered using either continuous ITPB (n = 19) or continuous IV fentanyl infusion (n = 41). Multivariable logistic regression analysis revealed that postoperative analgesia with continuous ITPB (P = 0.007), a lower incidence of major complications after surgery (P = 0.034), and female sex (P = 0.033) were significantly associated with a shorter postoperative LOHS. In subgroup analysis, patients who received continuous ITPB had significantly lower postoperative LOHS, lower postoperative serum C-reactive protein levels on postoperative day (POD) 3, and reduced acute postoperative pain on POD3 compared to those who received continuous IV fentanyl infusion.

Conclusions

Postoperative analgesia using continuous ITPB appears to be associated with a reduction in LOHS following P/D for MPM under general anesthesia.

[Assessment of the exposure of pest control operators to organophosphorus pesticides. Organophosphorus pesticides in blood and alkyl phosphate metabolites in urine]

Pest control operators usually spray pesticides in small areas such as a kitchen in a restaurant and are exposed to various pesticides, especially those of the organophosphorus (OP) type. In order to evaluate their occupational exposure to OP pesticides during the work, OP pesticides in blood and alkyl phosphate metabolites in urine of these operators were analyzed and the relationship between pesticide exposure and analytical results were studied. OP pesticides in blood were analyzed by gas chromatography with flame photometric detector (FPD-GC) after separation of phospholipid in blood with silicagel column chromatography. OP pesticides were not detected in any blood samples (the limit of detection was 1 ng/ml). Dimethylphosphate (DMP) and dimethylthiophosphate (DMTP), being urinary metabolites of OP pesticides, were analyzed by FPD-GC after benzyl derivatization. This method eliminated interfering peaks in gas chromatograms. The ratio of two isomeric derivatives of DMTP was found to be constant. Both DMP and DMTP of the exposed group were significantly higher than those of the non-exposed group, DMP being higher than DMTP. The ratio of DMP to DMTP in the fenitrothion-dichlorvos-exposed group was significantly higher than that in the fenitrothion-exposed group. It was considered that the ratio might reflect a result of pesticide exposure. The urinary metabolites of OP pesticides tended to become lower with the lapse of time since the last exposure. However, small amounts were detected in a few samples even 5 days after the last exposure.

Imaging evaluation of continuous extrapleural intercostal nerve block for minimally invasive cardiac surgery: a case report

Background

Spinal nerve block is difficult with minimally invasive cardiac surgery (MICS), because of the risk of serious bleeding complications due to full heparinization. Continuous extrapleural intercostal nerve block (CEINB) is a postoperative pain treatment for intercostal thoracotomy, with fewer complications. Here, we report a case in which imaging evaluation of CEINB with contrast medium was conducted to anatomically confirm the spread of local anesthetics after MICS.

Case presentation

A 65-year-old woman with severe mitral regurgitation underwent mitral valve plasty under general anesthesia via right-sided mini-thoracotomy. A CEINB catheter was placed before the incision was closed, without creating a conventional extrapleural pocket. We conducted an imaging evaluation with a contrast medium via the inserted catheter and confirmed sufficient spread around the intercostal nerve area. In addition, postoperative pain was well controlled by the nerve block.

Conclusions

Imaging evaluation of CEINB with contrast medium could increase analgesic quality and decrease complications post-MICS.

Effects of oral morphine on experimentally evoked itch and pain: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

Pain and itch share similar neuronal networks; hence, it is difficult to explain why opioids can relieve pain but provoke itching. The present human volunteer study aimed to investigate the similarities and differences in responses to experimentally provoked pain and itching to explore the underlying fundamental mechanisms.

METHODS

Twenty-four healthy volunteers were enrolled in this single-center, randomized, double-blind, placebo-controlled, parallel-group trial. Three volar forearms and two mandibular areas were marked, and participants randomly received morphine (20 mg) or identical placebo tablets. Heat, cold, and pressure pain thresholds, and vasomotor responses were assessed at baseline and after oral morphine administration. Itch provocations were induced by intradermal application of 1 % histamine or a topical cowhage (non-histaminergic itch) to a marked area of the skin. The participants were subsequently asked to rate their itching and pain intensities. The assessments were repeated for all marked areas.

RESULTS

Morphine caused analgesia, as assessed by the significant modulation of cold and pressure pain thresholds (p<0.05). There were no significant differences in histaminergic or non-histaminergic itch or pain intensity between the morphine and placebo groups. Superficial blood perfusion (vasomotor response) following histamine provocation was significantly increased by morphine (p<0.05) in both areas. No correlation was found between the provoked itch intensity and analgesic efficacy in any area or group.

CONCLUSIONS

Oral administration of morphine caused analgesia without modulating itch intensities but increased neurogenic inflammation in response to histamine, suggesting that different opioid mechanisms in histaminergic and non-histaminergic neurons evoke neurogenic inflammation.

Comprehensive health evaluation of workers in the ceramics industry

A cross sectional study on ceramics workers in the Seto area of Japan was conducted to determine whether there are differences in the morbidity pattern and overall health among the working populations employed by different sized companies engaged in the ceramics industry. The study population consisted of 3324 male ceramics workers (age range 40-69) who participated in the Seto occupational health screening programme in 1990. The prevalences of pulmonary diseases (silicosis and tuberculosis) and findings of some nonpulmonary diseases were compared in terms of company size by categories of 1-19, 20-49, 50-99, and 100 or more employees. The values of various screening tests were subjected to principle component analysis to extract factors representing key indices of health state. The average factor scores stratified by company size were used to quantitatively evaluate the comprehensive health level. Both prevalence and multivariate analysis showed that the employees working for smaller companies had overall worse health. The smaller the company, the higher the prevalence and the lower the health scores for silicosis and pulmonary tuberculosis tended to be; significantly increased rates and lower health scores for hypertension, anaemia, and glucosuria among small companies were also found when compared with larger companies. The high morbidity of silicosis and pulmonary tuberculosis in smaller companies contributed most to the decline in the overall health level.

[Automated microdetermination of lead in capillary blood from earlobes by flameless atomic absorption spectrophotometry]

Recent development of flameless atomic absorption spectrophotometry has made possible more precise and sensitive determinations of metals including lead. This means that a sample size of microliter order of blood has come to give a sufficient analytic signal. Blood lead which has usually been determined using venous blood was determined in the present study using a small amount of capillary blood. The method developed is of lead determination in the capillary blood sample from earlobe by means of flameless atomic absorption spectrophotometry equipped with an automated microsampling system or autosampler. Thus, 70 microliters of heparinized whole blood sample from earlobe gave a satisfactory result in the lead analysis. The procedure is as follows. 1) Blood obtained from the earlobe is collected in a heparinized capillary tube. 2) The blood is diluted in the ratio of 1 : 9 with Triton 5000 X solution for complete hemolysis of erythrocytes, by which the matrix-bound lead is released and a better distribution of samples is made possible in the graphite tube. 3) Finally the sample is analyzed by a flameless atomic absorption spectrophotometer with an autosampler. Making sure the analytical method to be accurate and reliable for blood lead determination, the authors compared capillary blood lead levels (Pb-Bc) with venous ones (Pb-Bv) from the same subjects in the same sampling session. It was found that the correlation between Pb-Bc and Pb-Bv was highly significant (n = 144, r = +0.998, y = 0.97 x+0.32, p less than 0.001) and that they were almost of the same level. It was concluded that the method developed may be recommended for the routine clinical use.