[Associations of onset age, diabetes duration and glycated hemoglobin level with ischemic stroke risk in type 2 diabetes patients: a prospective cohort study]

Objective: To investigate the associations of onset age, diabetes duration, and glycated hemoglobin (HbA1c) levels with ischemic stroke risk in type 2 diabetes patients. Methods: The participants were from Comprehensive Research on the Prevention and Control of the Diabetes in Jiangsu Province. The study used data from baseline survey from December 2013 to January 2014 and follow-up until December 31, 2021. After excluding the participants who had been diagnosed with stroke at baseline survey and those with incomplete information on onset age, diabetes duration, and HbA1c level, a total of 17 576 type 2 diabetes patients were included. Cox proportional hazard model was used to calculate the hazard ratio (HR) and 95%CI of onset age, diabetes duration, and HbA1c level for ischemic stroke. Results: During the median follow-up time of 8.02 years, 2 622 ischemic stroke cases were registered. Multivariate Cox proportional risk regression model showed that a 5-year increase in type 2 diabetes onset age was significantly associated with a 5% decreased risk for ischemic stroke (HR=0.95, 95%CI: 0.92-0.99). A 5-year increase in diabetes duration was associated with a 5% increased risk for ischemic stroke (HR=1.05, 95%CI: 1.02-1.10). Higher HbA1c (per 1 standard deviation increase:HR=1.17, 95%CI: 1.13-1.21) was associated with an increased risk for ischemic stroke. Conclusion: The earlier onset age of diabetes, longer diabetes duration, and high levels of HbA1c are associated with an increased risk for ischemic stroke in type 2 diabetes patients.

A two-circuit strategy for intraoperative extracorporeal support during single lung transplantation in a patient bridged with venovenous extracorporeal membrane oxygenation

Venovenous extracorporeal membrane oxygenation is increasingly used as a bridging strategy in decompensating patients awaiting lung transplantation. Various approaches for continuing support intraoperatively have been previously described. A two-circuit strategy that uses the in situ venovenous extracorporeal membrane oxygenation circuit supplemented with peripheral cardiopulmonary bypass allows for diversion of native cardiac output away from the transplanted lung as well as seamless continuation of venovenous extracorporeal membrane oxygenation postoperatively.

Hyperventilation and Respiratory Alkalosis After Olanzapine for Insomnia: A Case Report

Olanzapine is increasingly used as a sleep aid in hospitalized patients. Although thought to have less extrapyramidal effects, known side effects include oversedation, arrythmias, and hypotension. We present the unusual case of hyperventilation with respiratory alkalosis after the administration of olanzapine for insomnia in an elderly postoperative patient. This led to a second admission to the intensive care unit with invasive interventions including mechanical ventilation and vasopressor support. Caution must be exercised in prescribing antipsychotics for off-label use, especially in a population whose baseline characteristics can affect the pharmacokinetics of second-generation antipsychotics.

Severe Abdominal Wall Infection After Subcostal Transversus Abdominis Plane Block: A Case Report

Transversus abdominis plane (TAP) blocks are increasingly used for perioperative analgesia in patients undergoing abdominal surgeries. TAP blocks are easy to perform, reliably effective, and have an excellent safety profile. Nevertheless, we report a patient who underwent an open cholecystectomy and right hemicolectomy where a subcostal TAP block possibly contributed to an unusual abdominal wall abscess that lead to a prolonged and complicated postoperative course.

Recombinant activated factor VII for hemostasis in patients undergoing complex ascending aortic surgery: A single-center, single-surgeon retrospective analysis

BACKGROUND

Use of recombinant activated factor VII (rFVIIa) to achieve hemostasis during cardiac surgery continues to be debated, as support for its efficacy and safety has not been consistent. We examined our experience with rFVIIa for achieving hemostasis in high-risk patients undergoing complex ascending aortic surgery.

METHODS

We reviewed patients who underwent complex ascending aortic surgery performed by a single surgeon (C. K. R.) from August 2014 to February 2019. Outcomes of patients who received rFVIIa were compared with those who did not.

RESULTS

Of 59 consecutive patients, 20 patients (33.9%) received rFVIIa, whereas 39 (66.1%) did not. Median dose was 45.4 mcg/kg. rFVIIa was administered intraoperatively to 95% of patients who received it. Most patients underwent combined aortic valve, ascending aorta, and aortic arch surgery (80.0% vs. 64.1%, p = .52). Patients receiving rFVIIa had longer mean cross clamp times (212 vs. 173 min, p = .03) and received a greater median number of intraoperative blood products (18.5 vs. 12.0, p < .001). The number of patients who needed postoperative products (75.0% vs. 60.5%, p = .39), the median number of blood products transfused postoperatively (2 vs. 2, p = .40), and chest tube output (1138 vs. 805 ml, p = .17) were similar between groups. In-hospital mortality was similar between groups (10.0% vs. 10.3%, p = 1.00). Incidences of postoperative stroke (10.0% vs. 13.5%, p = 1.00) and thromboembolic events (10.0% vs. 13.5%, p = 1.00) were similar.

CONCLUSIONS

Administration of rFVIIa intraoperatively for refractory bleeding during complex ascending aortic surgery provided hemostasis without greater in-hospital mortality or a higher risk of stroke and thromboembolic events.

[Progress in metabolomics epidemiology]

In recent years, with the rapid development of metabonomic technology and analytic methods, metabolomics epidemiology, as an important branch of systems epidemiology, attracts more attention. Metabolomics epidemiology can better describe the characteristics of exposure, reflect the interaction between environmental factors and genetics, uncover the "black box" of the mechanisms underlying exposure and disease, and identify new biomarkers. This article briefly introduces the definition, methods, and progress of metabolomics epidemiology.

Body shape trajectories and the incidence of hypertension in a Mediterranean cohort: The sun study

AIMS

Our aim was to assess the association between trajectories of body-shape across the first 40 years of life and subsequent development of hypertension in a Mediterranean cohort.

METHODS AND RESULTS

We used a group-based modeling approach to assess body shape trajectories from age 5 to 40 years, among 7514 participants included in the SUN study (1999-2016), and assessed the subsequent incidence of hypertension. To create the trajectories, we used a censored normal model as a polynomial function of age. Cox models were used to estimates hazard ratios (HR) for hypertension according to body shape trajectories. Identified trajectories were "childhood lean -mid-life increase", "childhood medium-mid-life stable", " childhood heavy -mid-life decrease", and "childhood heavy -mid-life increase" for women; and "childhood lean-mid-life increase", "childhood medium-mid-life stable", "childhood medium -mid-life increase" and "childhood heavy-mid-life stable" for men. After a follow-up of 63,068 person-years, 865 incident cases of hypertension were found. Among women, compared to those in the "childhood medium-mid-life stable" trajectory, those, in the "childhood heavy -mid-life increase" trajectory showed higher risk to develop hypertension [HR = 1.72 (1.17-2.53)]. In men, compared with those in the "childhood medium-mid-life stable" trajectory, those in the "childhood lean and childhood medium -mid-life increase" and the "childhood heavy- mid-life stable" trajectories showed higher subsequent incidence of hypertension [HR = 1.43 (1.11-1.85), HR = 1.52 (1.17-1.97) and HR = 1.56 (1.14-2.14), respectively] after adjusting for potential confounders (including age, lifestyles, dietary intake, personality traits, physical activity and sedentary behaviors).

CONCLUSIONS

Our results suggest that mid-life increases in body shape or maintaining a heavy body shape during early and middle life in men and childhood heavy-mid-life increase in women is associated with a higher subsequent risk of developing hypertension in this Mediterranean population.

Surgical treatment for hypertrophic cardiomyopathy: a historical perspective

Our understanding of hypertrophic cardiomyopathy (HCM) as a disease entity has increased dramatically over the last half century. There has been a concerted effort by several surgical groups to develop operative techniques to relieve left ventricular outflow tract (LVOT) obstruction and alleviate symptoms. This paper traces the development of transaortic septal myectomy, the current gold standard therapy for relief of LVOT obstruction, in symptomatic patients refractory to medical treatment. In addition, we introduce newer methods for myectomy that have expanded the role of surgery in patients with various forms of HCM.

Mucopolysaccharidoses Causing Valvular Heart Disease: Report and Review of Surgical Management

Mucopolysaccharidosis type I is a genetic disorder with impaired glycosaminoglycan degradation. Cardiac pathologic involvement in this subset of patients is predominantly valvular heart disease. Valvular heart disease seen in these patients will most likely require surgical intervention in their lifetime. Only a limited amount of reports are dedicated to the cardiac surgical management of mucopolysaccharidoses. We present the case of a 32-year-old female with Hurler-Scheie syndrome who required multiple valve replacements due to progression of valvular dysfunction and decline in the quality of life. Multidisciplinary evaluation and discussion early are crucial for quality of life optimization in this cohort of patients.

[Association between genetic variants in microRNA biosynthesis genes and the risk of head and neck squamous cell carcinoma]

OBJECTIVE

To investigate the association between genetic variants in microRNA biosynthesis genes and the risk of head and neck squamous cell carcinoma (HNSCC).

METHODS

A case-control study was conducted with 576 HNSCC patients and 1 552 healthy controls matched by factors as age-(±5 years) and sex. Eight potentially functional single nucleotide polymorphism loci in microRNA biosynthesis genes (DICER1, GEMIN3, and PIWIL1) were genotyped using the Illumina Infinium BeadChip platform. Univariate and multivariate logistic regression models were performed to assess the association between genotypes and HNSCC risk.

RESULTS

The allele frequencies of rs1106042 (G> A) in PIWIL1 were significantly different between the cases and controls (P=0.011). After controlling for factors as age, sex, smoking and alcohol intake, the A allele of rs1106042 showed a decreased risk of HNSCC (additive model: adjusted OR=0.73, 95% CI: 0.57-0.93, P=0.011). RESULTS from the stratification analysis by age, sex, smoking, alcohol intake and tumor sites showed that the effect of rs1106042 A allele on HNSCC risk was significant in older age groups (≥60), females, nonsmokers, non-alcohol drinkers, and subjects with oral cavity cancer (P<0.05).

CONCLUSION

Potentially, functional single nucleotide polymorphism in PIWIL1 might modify the risk of HNSCC in China.

Model for end-stage liver disease excluding international normalized ratio (MELD-XI) score predicts heart transplant outcomes: Evidence from the registry of the United Network for Organ Sharing

BACKGROUND

Hepato-renal function is a valuable predictor of success after left ventricular assist device therapy and heart transplantation. Hence, we analyzed the importance of the Model for End-stage Liver Disease excluding international normalized ratio (MELD-XI) score to outcomes after heart transplant.

METHODS

Adults undergoing heart transplant from the United Network for Organ Sharing (UNOS) database were identified (1994 to 2014). Individual MELD-XI scores were calculated; patients were stratified by MELD-XI quartiles (Q1 to Q4). Multivariate logistic regression and the Cox proportional hazard model were implemented to determine any association between MELD-XI scores, survival and other outcomes.

RESULTS

From 39,711 patients undergoing OHT during the study period, MELD-XI score [median 10.7 (interquartile range 7.0 to 14.4)] was calculated for 36,005 patients (76% male and 75% white, 34% Status 1A). Higher MELD-XI scores had higher rates of pre-transplant extracorporeal membrane oxygenation, intra-aortic balloon pump, inotrope use and mechanical ventilation (p < 0.001 for all). Adjusted long-term mortality (median follow-up 8.1 years) was associated with MELD-XI score (hazard ratio [HR] 1.021 [1.016 to 1.026], p < 0.001). The highest MELD-XI quartile was associated with an HR 1.364 [1.255 to 1.482] risk of mortality compared with Q1. MELD-XI score was also associated with increased post-transplant infections (adjusted HR Q4 vs Q1: 1.364 [1.153 to 1.614], p < 0.001), stroke (adjusted HR Q4 vs Q1: 1.410 [1.074 to 1.852], p = 0.013), dialysis (adjusted HR Q4 vs Q1: 3.982 [3.386 to 4.683], p < 0.001), rejection (adjusted HR Q4 vs Q1: 1.519 [1.286 to 1.795], p = 0.003) and prolonged hospitalization (adjusted HR Q4 vs Q1: 1.635 [1.429 to 1.871], p < 0.001).

CONCLUSION

Hepato-renal dysfunction, measured with MELD-XI score, predicts morbidity and mortality in patients undergoing orthotopic heart transplantation. Etiology of hepato-renal dysfunction should be sought and treated before heart transplantation.

Model for end-stage liver disease excluding international normalized ratio (MELD-XI) score predicts heart transplant outcomes: Evidence from the registry of the United Network for Organ Sharing

BACKGROUND

Hepato-renal function is a valuable predictor of success after left ventricular assist device therapy and heart transplantation. Hence, we analyzed the importance of the Model for End-stage Liver Disease excluding international normalized ratio (MELD-XI) score to outcomes after heart transplant.

METHODS

Adults undergoing heart transplant from the United Network for Organ Sharing (UNOS) database were identified (1994 to 2014). Individual MELD-XI scores were calculated; patients were stratified by MELD-XI quartiles (Q1 to Q4). Multivariate logistic regression and the Cox proportional hazard model were implemented to determine any association between MELD-XI scores, survival and other outcomes.

RESULTS

From 39,711 patients undergoing OHT during the study period, MELD-XI score [median 10.7 (interquartile range 7.0 to 14.4)] was calculated for 36,005 patients (76% male and 75% white, 34% Status 1A). Higher MELD-XI scores had higher rates of pre-transplant extracorporeal membrane oxygenation, intra-aortic balloon pump, inotrope use and mechanical ventilation (p < 0.001 for all). Adjusted long-term mortality (median follow-up 8.1 years) was associated with MELD-XI score (hazard ratio [HR] 1.021 [1.016 to 1.026], p < 0.001). The highest MELD-XI quartile was associated with an HR 1.364 [1.255 to 1.482] risk of mortality compared with Q1. MELD-XI score was also associated with increased post-transplant infections (adjusted HR Q4 vs Q1: 1.364 [1.153 to 1.614], p < 0.001), stroke (adjusted HR Q4 vs Q1: 1.410 [1.074 to 1.852], p = 0.013), dialysis (adjusted HR Q4 vs Q1: 3.982 [3.386 to 4.683], p < 0.001), rejection (adjusted HR Q4 vs Q1: 1.519 [1.286 to 1.795], p = 0.003) and prolonged hospitalization (adjusted HR Q4 vs Q1: 1.635 [1.429 to 1.871], p < 0.001).

CONCLUSION

Hepato-renal dysfunction, measured with MELD-XI score, predicts morbidity and mortality in patients undergoing orthotopic heart transplantation. Etiology of hepato-renal dysfunction should be sought and treated before heart transplantation.

Levosimendan Reduces Mortality in Adults with Left Ventricular Dysfunction Undergoing Cardiac Surgery: A Systematic Review and Meta-analysis

INTRODUCTION

Levosimendan is implemented in patients with low cardiac output after cardiac surgery. However, the strength of evidence is limited by randomized controlled trials enrolling a small number of patients. Hence we have conducted a systematic review to determine the role of levosimendan in adult cardiac surgery.

METHODS

PUBMED, WoS, Cochrane database, and SCOPUS were systematically queried to identify original English language peer-reviewed literature (inception-October 2014) comparing clinical results of adult cardiac surgery between levosimendan and control. Pooled odds ratio (OR) was calculated using the Peto method; p < 0.05 is significant; results are presented within 95% confidence intervals. Continuous data was compared using standardized mean difference/mean difference.

RESULTS

Fourteen studies were included in the analysis. Levosimendan reduced early mortality in patients with reduced ejection fraction (5.5% vs. 9.1%) (OR 0.48 [0.23-0.76]; p = 0.004). This result was confirmed using sensitivity analysis. Postoperative acute renal failure was lower with levosimendan therapy (7.4% vs. 11.5%). Intensive care unit stay was shorter in the levosimendan cohort comparable in both groups (standardized mean difference -0.31 [-0.53, -0.09]; p = 0.006; I(2)  = 33.6%). Levosimendan-treated patients stayed 1.01 (1.61-0.42) days shorter when compared to control (p = 0.001).

CONCLUSION

Our meta-analysis demonstrates that Levosimendan improves clinical outcomes in patients with left ventricular dysfunction undergoing cardiac surgery. Results of the ongoing multicenter randomized controlled trial are awaited to provide more conclusive evidence regarding the benefit of this drug.

Coronary Artery Bypass Grafting After Percutaneous Intervention Has Higher Early Mortality: A Meta-Analysis

BACKGROUND

We compared early adverse events and midterm survival between primary coronary artery bypass grafting (pCABG) and CABG in patients with percutaneous intervention (secondary CABG, sCABG) because data on this topic are very limited.

METHODS

A systematic review of published literature was done to obtain original studies fulfilling the search criteria. The end points studied were early mortality, stroke, renal failure, myocardial infarction, and the need for an intra-aortic balloon pump. A random-effect inverse variance weighted analysis was performed. The results are presented as risk ratios (RR) (95% confidence interval); p < 0.05 was considered statistically significant.

RESULTS

Fourteen studies (84,983 pCABG patients and 14,775 sCABG patients) were included in the systematic review. Early mortality was lower with primary CABG (RR 1.54 [1.19-2]; p = 0.007). The incidence of myocardial infarction was also less with pCABG than with sCABG. (RR 1.46 [1.04-2.06]; p = 0.06). Patients undergoing pCABG were 14% (0% to 55%; p = 0.04). Less likely to need an intra-aortic balloon pump. Although renal failure was lower with pCABG (RR 1.254 [1.047-1.502]; p = 0.014), the stroke rates were comparable in both cohorts (p = 0.95). Renal failure was favorable in the primary CABG cohort. Early stroke was comparable between the two cohorts (p = 0.95). The pooled hazard ratios demonstrated comparable survival at the end of 3 years (p = 0.36).

CONCLUSIONS

Patients undergoing CABG after prior percutaneous therapy have a higher incidence of myocardial infarction and mortality in the postoperative period. However, midterm survival is comparable in both cohorts.

Levosimendan Reduces Mortality in Adults with Left Ventricular Dysfunction Undergoing Cardiac Surgery: A Systematic Review and Meta-analysis

INTRODUCTION

Levosimendan is implemented in patients with low cardiac output after cardiac surgery. However, the strength of evidence is limited by randomized controlled trials enrolling a small number of patients. Hence we have conducted a systematic review to determine the role of levosimendan in adult cardiac surgery.

METHODS

PUBMED, WoS, Cochrane database, and SCOPUS were systematically queried to identify original English language peer-reviewed literature (inception-October 2014) comparing clinical results of adult cardiac surgery between levosimendan and control. Pooled odds ratio (OR) was calculated using the Peto method; p < 0.05 is significant; results are presented within 95% confidence intervals. Continuous data was compared using standardized mean difference/mean difference.

RESULTS

Fourteen studies were included in the analysis. Levosimendan reduced early mortality in patients with reduced ejection fraction (5.5% vs. 9.1%) (OR 0.48 [0.23-0.76]; p = 0.004). This result was confirmed using sensitivity analysis. Postoperative acute renal failure was lower with levosimendan therapy (7.4% vs. 11.5%). Intensive care unit stay was shorter in the levosimendan cohort comparable in both groups (standardized mean difference -0.31 [-0.53, -0.09]; p = 0.006; I(2)  = 33.6%). Levosimendan-treated patients stayed 1.01 (1.61-0.42) days shorter when compared to control (p = 0.001).

CONCLUSION

Our meta-analysis demonstrates that Levosimendan improves clinical outcomes in patients with left ventricular dysfunction undergoing cardiac surgery. Results of the ongoing multicenter randomized controlled trial are awaited to provide more conclusive evidence regarding the benefit of this drug.

Prognostic value of the stem cell markers CD133 and ABCG2 expression in esophageal squamous cell carcinoma

In the light of increasing evidence supporting cancer stem cells (CSCs) theory, the expression of two stem cell markers, CD133 and adenosine triphosphate-binding cassette superfamily G member 2 (ABCG2), in esophageal squamous cell carcinoma (ESCC) was investigated, and their prognostic values were evaluated. Paraffin-embedded tissue sections of 110 ESCC patients were investigated using Immunohistochemistry. The association of CD133 and ABCG2 expression with clinicopathologic characteristics was analyzed by χ(2) test. Survival analysis was carried out using Kaplan-Meier method and Cox proportional hazards model. CD133 and ABCG2 expression were detected in 27.3% and 15.5% of ESCC patients, respectively. The presence of CD133-positive cancer cells was associated with tumor cell differentiation (P= 0.008) but not significantly related to the survival of ESCC patients (P= 0.085). ABCG2 expression was not associated with clinicopathologic characteristics but was a significant prognostic factor for adverse overall survival of ESCC patients (P= 0.005). The median overall survival time for ESCC patients with and without ABCG2 expression were 21.8 and >49.3 months, respectively. A combined analysis of CD133 and ABCG2 expression did not show that ESCC patients with coexpression of these two markers had a worse prognosis than those with only ABCG2 expression (P= 0.934). Moreover, ABCG2 expression was revealed to be an independent prognostic factor along with tumor node metastasis stage in multivariate analysis (hazard ratio of ABCG2, 3.38; 95% confidence interval, 1.61∼7.09; P= 0.001). By survival analysis based on tumor node metastasis stage of ESCC, the association between ABCG2 expression and the patients' prognosis was found significant in the group of relatively early stage (P= 0.005) and marginally significant in the group of relatively late stage (P= 0.058). This is the first time to report the presence of CD133-positive cancer cells in ESCC but not supporting its prognostic value and validity as a CSC marker for ESCC. ABCG2 expression was found to correlate with the survival of ESCC patients, especially those at relatively early stage, suggesting that ABCG2-positive cancer cells may represent a pool of CSCs in ESCC, and relatively early-stage patients with ABCG2 expression may deserve more intensive or targeted therapy.

Quantitative test of knee laxity in Chinese

Anterior knee laxity of 100 Chinese male subjects who had no history of previous injuries to their knees was examined with an instrumented knee arthrometer (MEDmetric Knee Arthrometer, model KT-1000). Two measurements were used to evaluate the anterior laxity: 1) anterior displacement produced by anterior force of 89 newtons (20 lbs); and 2) anterior compliance index (ACI), the displacement difference between an anterior force of 89 newtons (20 lbs) and 67 newtons (15 lbs). All knees were examined at a flexion angle of 20 +/- 5 degrees and an external tibial rotation of 10 +/- 5 degrees with the use of thigh and foot supports. The mean anterior displacement for the right and left knee were 4.5 +/- 2.0 mm and 4.3 +/- 1.9 mm, respectively, while 84% of the study subjects had right and left differences (anterior displacement difference, ADD) of less than 2 mm. The anterior compliance index was 0.85 +/- 0.4 mm for the right knee and 0.78 +/- 0.33 mm for the left knee. The mean anterior compliance index difference (CID), that is the difference between the right and left ACI, was 0.25 +/- 0.3 mm. A total of 93% of the subjects had a difference in the right-left CID of less than 0.5 mm. Variation between the right and left knee does exist, but the difference is not statistically significant (p > 0.05). Therefore, comparison of the right-left ADD and CID can be a useful reference in the assessment of a ligamentous injury.

Effects of stress on morphine-elicited locomotor activity in hamsters

Two experiments were conducted to investigate the effects of stress on morphine-elicited locomotor activity in hamsters. In Experiment 1, half of the animals were habituated to handling and injection procedures (low-stress condition) and half were not (high-stress condition) prior to 6 days of testing with a low dose (2.5 mg/kg) of morphine. On the first test day, morphine elicited hyperactivity among habituated animals, whereas among nonhabituated animals morphine elicited hypoactivity. The effects of handling diminished across test days, so that on the last test day, morphine elicited hyperactivity in both habituated and nonhabituated animals. In Experiment 2, the effect of a noise stressor on activity elicited by three doses of morphine (2.5, 5.0, and 15 mg/kg) was investigated. Half of the animals were tested under conditions of low noise stress (70 dB), and half were tested under conditions of high noise stress (90 dB). Results indicated that the effects of each dose of morphine were potentiated in the high-stress relative to the low-stress condition. Both experiments demonstrated that environmental stressors can potentiate the response to exogenous opiate administration in hamsters. Moreover, the results are consistent with the hypothesis that stress induces the release of endogenous opioids which summate with exogenous opiates to determine the final effective dose.

Effects of stress on morphine-elicited locomotor activity in hamsters

Two experiments were conducted to investigate the effects of stress on morphine-elicited locomotor activity in hamsters. In Experiment 1, half of the animals were habituated to handling and injection procedures (low-stress condition) and half were not (high-stress condition) prior to 6 days of testing with a low dose (2.5 mg/kg) of morphine. On the first test day, morphine elicited hyperactivity among habituated animals, whereas among nonhabituated animals morphine elicited hypoactivity. The effects of handling diminished across test days, so that on the last test day, morphine elicited hyperactivity in both habituated and nonhabituated animals. In Experiment 2, the effect of a noise stressor on activity elicited by three doses of morphine (2.5, 5.0, and 15 mg/kg) was investigated. Half of the animals were tested under conditions of low noise stress (70 dB), and half were tested under conditions of high noise stress (90 dB). Results indicated that the effects of each dose of morphine were potentiated in the high-stress relative to the low-stress condition. Both experiments demonstrated that environmental stressors can potentiate the response to exogenous opiate administration in hamsters. Moreover, the results are consistent with the hypothesis that stress induces the release of endogenous opioids which summate with exogenous opiates to determine the final effective dose.

Naloxone reversal of morphine elicited hyperactivity

When naloxone is administered during morphine elicited hyperactivity, hyperactivity is reversed and hypoactivity occurs in its place. The present experiment tested the hypothesis that this effect is the result of morphine induced supersensitivity to naloxone. Two groups of hamsters received equivalent pretreatment with 15 mg/kg morphine (Groups M/M and M/S) for three days while a third group received saline (Group S/S). During subsequent testing one group received a morphine injection (Group M/M) while the others received saline (Groups M/S and S/S) before being placed in running wheels for a three hour session. Two hours later half the animals in each group received an injection of 0.4 mg/kg naloxone and half received saline. Naloxone produced hypoactivity in animals running under the influence of morphine (Group M/M), but neither in those with an equivalent history of morphine pre-treatment (Group M/S), nor in saline controls (Group S/S). These results are inconsistent with the hypothesis under test, but congruent with a modified dual-action hypothesis.

Activation of chicken liver fructose- 1,6-bisphosphatase by oxidized glutathione

Treatment of chicken liver fructose- 1,6-bisphosphatase with oxidized glutathione (GSSG) leads to an increase in activity. This activation is markedly enhanced if treatment is performed in the presence of AMP or Mn2+. The effects of AMP and Mn2+ appear to be synergistic. The maximal activation is over 13-fold and is accompanied by the disappearance of 4 sulfhydryl groups per molecule of enzyme. Both fructose 1,6-bisphosphate and fructose 2,6-bisphosphate can largely prevent this activation. Activation can be reversed by dithiothreitol or cysteine. It appears that GSSG activates this enzyme by thiol/disulfide exchanges with the enzyme's specific sulfhydryl groups.