Pain and aetiological risk factors determine quality of life in patients with chronic pancreatitis, but a brick in the puzzle is missing

BACKGROUND AND OBJECTIVES

Chronic pancreatitis (CP) is a debilitating fibro-inflammatory disease with a profound impact on patients' quality of life (QOL). We investigated determinants of QOL in a large cohort of CP patients.

METHODS

This was a multicentre study including 517 patients with CP. All patients fulfilled the EORTC QLQ-C30 questionnaire. Questionnaire responses were compared to results obtained from a general reference population (n = 11,343). Demographic characteristics, risk factors (smoking and alcohol consumption), pain symptoms, disease phenotype (complications) and treatments were recorded. A multivariable regression model was used to identify factors independently associated with QOL scores.

RESULTS

Included patients had a mean age of 56.3 ± 12.8 years, 355 (69%) were men and 309 (60%) had alcohol aetiology. Compared to the reference population, patients with CP had lower global health status (50.5 vs. 66.1; p < 0.001) as well as reduced scores for all functional scales (all p < 0.001). Additionally, CP patients reported a higher burden for all symptom items, with pain being the most prominent complaint (all p < 0.001). Constant pain (coefficient -11.3; p = 0.02), opioid based pain treatment (coefficient -19.7; p < 0.001) and alcoholic aetiology (coefficient -5.1; p = 0.03) were independently associated with lowered global health status. The final multivariable model explained 18% of the variance in global health status.

CONCLUSIONS

Patients with CP have significantly lower QOL compared to a population-based reference population. Factors independently associated with a lowered QOL are constant pain, opioid based pain treatment and alcohol aetiology. However, these factors only explain a fraction of QOL and additional factors need identification.

Association of multiple patient and disease characteristics with the presence and type of pain in chronic pancreatitis

BACKGROUND AND AIM

Pain is the primary symptom of chronic pancreatitis (CP) and associates with a number of patient and disease characteristics. However, the complex interrelations of these parameters are incompletely understood, and pain treatment remains unsatisfactory in a large proportion of patients. The aim of this study is to investigate multiple pain risk factors in a large population of CP patients, with a special emphasis on patients' patterns of smoking and alcohol use.

METHODS

This was a multicenter, cross-sectional study including 1384 patients with CP. Patient demographics and disease characteristics, as well as current patterns of smoking and alcohol use, were compared for patients with pain (n = 801) versus without pain (n = 583). Multivariate logistic regression models were performed to assess the variables associated with the presence and type of pain (constant vs intermittent pain).

RESULTS

The mean age of participants was 52.1 ± 14.6 years, and 914 (66%) were men. Active smoking (odds ratio 1.6 [95% confidence interval 1.1-2.2], P = 0.005) and alcohol consumption (odds ratio 1.8 [95% confidence interval 1.1-3.0], P = 0.03) were independently associated with the presence of pain. In addition, patients' age at diagnosis, pancreatic duct pathology, and the presence of pseudocysts, duodenal stenosis, and exocrine pancreatic insufficiency were confirmed as pain risk factors (all P ≤ 0.01). Constant pain, as opposed to intermittent pain, was more frequently reported by smokers (P = 0.03), while alcohol consumption was associated with intermittent pain (P = 0.006).

CONCLUSION

Multiple patient and disease characteristics, including patterns of smoking and alcohol consumption, associate with the presence and type of pain in patients with CP.

Multiple risk factors for diabetes mellitus in patients with chronic pancreatitis: A multicentre study of 1117 cases

BACKGROUND

Diabetes mellitus is a common complication of chronic pancreatitis. It is traditionally considered to develop as a consequence of beta cell loss, but there might be additional factors. Recent studies have highlighted the importance of type 2 diabetes-related risk factors in this context and population-based studies show increased risk of diabetes following acute pancreatitis. The aim of this study was to explore multiple risk factors for diabetes in patients with chronic pancreatitis.

METHODS

We conducted a multicentre, cross-sectional study of patients with definitive chronic pancreatitis according to the M-ANNHEIM criteria. We used multivariable logistic regression models to determine risk factors independently associated with diabetes.

RESULTS

The study included 1117 patients of whom 457 (40.9 %) had diabetes. The mean age was 52.8 ± 14.2 years and 67% were men. On multivariate analysis, parameters indicative of beta cell loss (pancreatic calcification, exocrine insufficiency, pancreatic resection) were confirmed as independent risk factors for diabetes (all p ≤ 0.02). In addition, type 2 diabetes-related risk factors (dyslipidaemia and overweight/obesity) were associated with the presence of diabetes (all p ≤ 0.002). Patients with a history of pancreatic fluid collections (indicative of previous attacks of acute pancreatitis) had a marginally increased risk of diabetes (p = 0.07).

CONCLUSION

In patients with chronic pancreatitis the presence of diabetes is associated with multiple risk factors including type 2 diabetes-related factors. Our observations attest to the understanding of this entity and may have implications for treatment.

Anti-TNF Therapy in Pregnant Women With Inflammatory Bowel Disease: Effects of Therapeutic Strategies on Disease Behavior and Birth Outcomes

BACKGROUND

Active inflammatory bowel disease (IBD) adversely affects pregnancy outcomes. Little is known about the risk of relapse after stopping anti-tumor necrosis factor (anti-TNF) treatment during pregnancy. We assessed the risk of relapse before delivery in women who discontinued anti-TNF treatment before gestational week (GW) 30, predictors of reduced infant birth weight, a marker associated with long-term adverse outcomes, and rates and satisfaction with counseling.

METHODS

Pregnant women with IBD receiving anti-TNF treatment were prospectively invited to participate in an electronic questionnaire carried out in 22 hospitals in Denmark, Australia, and New Zealand from 2011 to 2015. Risk estimates were calculated, and birth weight was investigated using t tests and linear regression.

RESULTS

Of 175 women invited, 153 (87%) responded. In women in remission, the relapse rate did not differ significantly between those who discontinued anti-TNF before GW 30 (1/46, 2%) compared with those who continued treatment (8/74, 11%; relative risk, 0.20; 95% confidence interval [CI], 0.02 to 1.56; P = 0.08). Relapse (P = 0.001) and continuation of anti-TNF therapy after GW 30 (P = 0.007) were independently associated with reduced mean birth weight by 367 g (95% CI, 145 to 589 g; relapse) and 274 g (95% CI, 77 to 471 g; anti-TNF exposure after GW 30). Of 134 (88%) women who received counseling, 116 (87%) were satisfied with the information provided.

CONCLUSIONS

To minimize fetal exposure in women in remission, discontinuation of anti-TNF before GW 30 seems safe. Relapse and continuation of anti-TNF therapy after GW 30 were each independently associated with lower birth weight, although without an increased risk for birth weight <2500 g. Most women received and were satisfied with counseling.

Pancreatic calcifications associate with diverse aetiological risk factors in patients with chronic pancreatitis: A multicentre study of 1500 cases

BACKGROUND

Pancreatic calcifications is a common finding in patients with chronic pancreatitis (CP), but the underlying pathophysiology is incompletely understood. Past studies for risk factors of calcifications have generally been focused on single parameters or limited by small sample sizes. The aim of this study was to explore several patient and disease characteristics and their associations with pancreatic calcifications in a large cohort of CP patients with diverse aetiological risk factors.

METHODS

This was a multicentre, cross-sectional study including 1509 patients with CP. Patient and disease characteristics were compared for patients with calcifications (n = 912) vs. without calcifications (n = 597). Multivariable logistic regression was performed to assess the parameters independently associated with calcifications.

RESULTS

The mean age of patients was 53.9 ± 14.5 years and 1006 (67%) were men. The prevalence of calcifications was 60.4% in the overall patient cohort, but highly variable between patients with different aetiological risk factors (range: 2-69%). On multivariate analysis, alcoholic aetiology (OR 1.76 [95% CI, 1.39-2.24]; p < 0.001) and smoking aetiology (OR 1.77 [95% CI, 1.39-2.26], p < 0.001) were positively associated with the presence of calcifications, while an autoimmune aetiology was negatively associated with calcifications (OR 0.15 [95% CI, 0.08-0.27], p < 0.001). Patients with pancreatic calcifications were more likely to have undergone pancreatic duct stenting (OR 1.59 [95%CI, 1.16-2.19], p = 0.004).

CONCLUSION

The presence of pancreatic calcifications is associated with diverse aetiological risk factors in patients with CP. This observation attest to the understanding of CP as a complex disease and may have implications for disease classification.

The Scandinavian baltic pancreatic club (SBPC) database: design, rationale and characterisation of the study cohort

OBJECTIVES

Chronic pancreatitis (CP) is a multifaceted disease associated with several risk factors and a complex clinical presentation. We established the Scandinavian Baltic Pancreatic Club (SBPC) Database to characterise and study the natural history of CP in a Northern European cohort. Here, we describe the design of the database and characteristics of the study cohort.

METHODS

Nine centres from six different countries in the Scandinavian-Baltic region joined the database. Patients with definitive or probable CP (M-ANNHEIM diagnostic criteria) were included. Standardised case report forms were used to collect several assessment variables including disease aetiology, duration of CP, preceding acute pancreatitis, as well as symptoms, complications, and treatments. The clinical stage of CP was characterised according to M-ANNNHEIM. Yearly follow-up is planned for all patients.

RESULTS

The study cohort comprised of 910 patients (608 men: 302 women; median age 58 (IQR: 48-67) years with definite 848 (93%) or probable CP 62 (7%). Nicotine (70%) and alcohol (59%) were the most frequent aetiologies and seen in combination in 44% of patients. A history of recurrent acute pancreatitis was seen in 49% prior to the development of CP. Pain (69%) and exocrine pancreatic insufficiency (68%) were the most common complications followed by diabetes (43%). Most patients (30%) were classified as clinical stage II (symptomatic CP with exocrine or endocrine insufficiency). Less than 10% of the patients had undergone pancreatic surgery.

CONCLUSION

The SBPC database provides a mean for future prospective, observational studies of CP in the Northern European continent.

An update on targeted gene repair in mammalian cells: methods and mechanisms

Transfer of full-length genes including regulatory elements has been the preferred gene therapy strategy for clinical applications. However, with significant drawbacks emerging, targeted gene alteration (TGA) has recently become a promising alternative to this method. By means of TGA, endogenous DNA repair pathways of the cell are activated leading to specific genetic correction of single-base mutations in the genome. This strategy can be implemented using single-stranded oligodeoxyribonucleotides (ssODNs), small DNA fragments (SDFs), triplex-forming oligonucleotides (TFOs), adeno-associated virus vectors (AAVs) and zinc-finger nucleases (ZFNs). Despite difficulties in the use of TGA, including lack of knowledge on the repair mechanisms stimulated by the individual methods, the field holds great promise for the future. The objective of this review is to summarize and evaluate the different methods that exist within this particular area of human gene therapy research.

A rapid, endoscopic exocrine pancreatic function test and the Lundh test: a comparative study

BACKGROUND/AIMS

The diagnosis of chronic pancreatitis is often difficult in the early stages of the disease. Morphological tests may be normal, and reliable methods for the evaluation of the exocrine pancreatic function are time-consuming and troublesome. A new test for exocrine pancreatic function, using endoscopic aspiration of secretin-stimulated pancreatic juice, has been developed. We evaluated the test using the Lundh meal test as reference.

METHODS

The endoscopic secretin stimulation test (ESST) was performed in a consecutive row of 24 patients referred for pancreatic function testing because of clinical suspicion of chronic pancreatitis and in 23 healthy volunteers. The participants fasted overnight and secretin was given intravenously (1 CU/kg) as a bolus the following morning. Thirty minutes after administration of secretin, the tip of the duodenoscope was placed close to the ampulla of Vater and duodenal aspirate was drawn for 10 min. Intraduodenal concentrations of lipase, bicarbonate, elastase and zinc were measured. The concentration of lipase during the Lundh test (4 x 20 min aspiration) was used as reference test in the patients.

RESULTS

Judged from the Lundh test, the exocrine pancreatic function was nearly abolished in 5 patients (<10% of lower normal limit), reduced in 6 patients and normal in 13 patients. ESST failed in 1 patient (no aspirate). Lipase concentrations (KU/l) were significantly lower in the patients with nearly abolished function compared to patients with reduced or normal exocrine pancreatic function (NEPF; Mann-Whitney U test: p < 0.01), but an overlap was found between patients with reduced exocrine pancreatic function [100.1 (median); 60.0-225.0 (range)] patients with NEPF (145.7; 44.6-268.0) and healthy controls (175.0; 84.8-381.0). Bicarbonate concentrations (mEq/l) were significantly lower in patients with reduced exocrine pancreatic function (51.2; 32.5-69.6) compared to patients with NEPF (80.0; 48.1-101.8; Mann-Whitney U test: p < 0.05). Pancreatic elastase concentration was significantly lower in the group with nearly abolished exocrine function compared to patients with NEPF (Mann-Whitney U test: p < 0.05), but there was no difference between elastase concentrations among the other groups. We found significant correlation between lipase and bicarbonate concentrations during ESST and lipase concentrations during the Lundh test in all 23 patients (Spearman's Rank test: rho = 0.597 and 0.683, respectively, p < 0.01). By using receiver operating characteristic curves, best cut-off point for bicarbonate was estimated. Lipase and bicarbonate results in the healthy volunteers were not statistically different from results in patients with NEPF. No side effects were observed except for worsening of nausea and abdominal pain in 2 of the patients.

CONCLUSION

The ESST is safe, and by combining the estimation of lipase and bicarbonate concentrations this test is a rapid, easy and useful diagnostic test for exocrine pancreatic function.

Studies of genetic variability of the glucose transporter 2 promoter in patients with type 2 diabetes mellitus

This study was performed to test the hypothesis that genetic variation in the promoter of the glucose transporter 2 (GLUT2) might predispose to prediabetic phenotypes or type 2 diabetes. A total of 1611 bp comprising the minimal promoter region of the GLUT2 gene were examined by combined single-strand conformational polymorphism and heteroduplex analysis followed by direct sequencing of identified variants on genomic DNA from 96 randomly recruited Danish type 2 diabetic patients. We identified 4 nucleotide variants, -447g-->a, -149c-->a, -122t-->c, and -44g-->a. None of the variants were positioned in known or presumed transcription factor binding sites, TATA-box, or transcriptional start site. Association studies of the -149c-->a, -122t-->c, and -44g-->a variants revealed that the variants were as prevalent in 320 type 2 diabetic patients [11.0% (95% confidence interval, 8.4-13.6), 9.8% (7.4-12.2), and 29.0% (24.4-33.6), respectively] as in 241 age-matched glucose-tolerant subjects [13.1% (9.8-16.4), 11.2% (8.3-14.1), and 33.4% (28.8-38.0), respectively]. The -447g-->a mutation was only identified in a single diabetic patient and did not show cosegregation with diabetes in the family of the proband. The three common variants showed in a primary genotype-phenotype study comprising 241 glucose-tolerant middle-aged subjects association to increased plasma glucose levels during an oral glucose tolerance test. However, this result could not be replicated in a second sample of 298 60-yr-old glucose-tolerant subjects. In conclusion, we found no evidence supporting the hypothesis that genetic variability in the minimal promoter of the GLUT2 is associated with type 2 diabetes or prediabetic phenotypes in the Danish population.

Low-dose oral iron absorption test in anaemic patients with and without iron deficiency determined by bone marrow iron content

The low-dose oral iron absorption test (OIAT) was performed in 85 consecutive anaemic patients referred for bone marrow examination in order to investigate the ability of the test to predict bone marrow iron stores and to differentiate between different categories of anaemia. Eight patients were excluded for technical reasons. Test results from 77 patients are presented as Cmax (micromol/l): the maximum increase in S-iron measured during a 3 h period after administration of 10 mg oral iron sulfate. Iron deficiency was defined as the absence of stainable iron in bone marrow aspirates. Cmax was higher in 46 iron deficient patients [3 (median); 0 and 13 (1st and 3rd quartiles); 0-40 (range)] than in 31 non-iron-deficient patients (0; 0 and 2; 0-4) (P<0.01). 27 patients had primary bone marrow disease, 25 patients had absent bone marrow iron stores accompanied by inflammation, 17 patients had anaemia of chronic disease (ACD) and 8 patients had uncomplicated iron deficiency anaemia (IDA). Patients with IDA had higher Cmax (15; 13 and 28; 6-40) than patients with ACD (1; 0 and 2; 0-3), and than the 69 non-IDA patients (1; 0 and 3; 0-19) (P<0.001). Cmax values above 5 micromol/l always indicated absent bone marrow iron stores.

Low-dose oral iron absorption test: establishment of a reference interval

The low-dose oral iron absorption test (OIAT), a possible test for iron deficiency, is based on the fact that intestinal iron absorption is higher in iron-deficient subjects than in those with normal or increased iron stores. The aims of this study were to establish a reference interval for the OIAT, to evaluate five different ways of presenting the results, and to advocate for the use of one of these methods. OIAT was performed in 122 healthy volunteers, 3 of whom were excluded as a result of technical difficulties. The volunteers were given 10 mg of oral iron sulphate at 0900 h on an empty stomach. S-iron was measured just before iron consumption, and after 1, 2 and 3 h. The maximum increase in S-iron during the test, presented as Cmax (micromol l(-1)), was higher in females (5 [median]; 3 and 7 [1st and 3rd quartiles]; 0-34 [range]) than in males (3; 1 and 5; 0-13) (p<0.001 Mann Whitney U-test). Furthermore, Cmax was significantly higher in females aged 22 44 years than in all other age groups (males and females), but did not fluctuate significantly with age in males. Cmax was higher in premenopausal than in postmenopausal females (6; 5 and 10; 0-34 and 4; 2 and 5; 0-12, respectively) (p <0.01 Mann Whitney U-test). In conclusion, iron absorption assessed by the OIAT was higher in premenopausal females than in postmenopausal females and males. We suggest reference intervals of 0-34 micromol l(-1) in premenopausal females, and 0-11 micromol l(-1) in all other persons, i.e. males and postmenopausal females.

[Hepatitis C virus transmission between two brothers]

We present a case where a 30 year-old male by accident probably infected his older brother with hepatitis C-virus. After two months this older brother suffered from acute hepatitis C, and within 16 months he showed progression to chronic hepatitis C.

Meta-analysis of randomized control trials addressing brief interventions in heavy alcohol drinkers

OBJECTIVE

To assess the effectiveness of brief interventions in heavy drinkers by analyzing the outcome data and methodologic quality.

DESIGN

(1) Qualitative analysis of randomized control trials (RCTs) using criteria from Chalmers' scoring system; (2) calculating and combining odds ratios (ORs) of RCTs using the One-Step (Peto) and the Mantel-Haenszel methods. STUDY SELECTION AND ANALYSIS: A MEDLINE and PsycLIT search identified RCTs testing brief interventions in heavy alcohol drinkers. Brief interventions were less than 1 hour and incorporated simple motivational counseling techniques much like outpatient smoking cessation programs. By a single-reviewer, nonblinded format, eligible studies were selected for adult subjects, sample sizes greater than 30, a randomized control design, and incorporation of brief alcohol interventions. Methodologic quality was assessed using an established scoring system developed by Chalmers and colleagues. Outcome data were combined by the One-Step (Peto) method; confidence limits and chi 2 test for heterogeneity were calculated.

RESULTS

Twelve RCTs met all inclusion criteria, with an average quality score of 0.49 + or - 0.17. This was comparable to published average scores in other areas of research (0.42 + or - 0.16). Outcome data from RCTs were pooled, and a combined OR was close to 2 (1.91; 95% confidence interval 1.61-2.27) in favor of brief alcohol interventions over no intervention. This was consistent across gender, intensity of intervention, type of clinical setting, and higher-quality clinical trials.

CONCLUSIONS

Heavy drinkers who received a brief intervention were twice as likely to moderate their drinking 6 to 12 months after an intervention when compared with heavy drinkers who received no intervention. Brief intervention is a low-cost, effective preventive measure for heavy drinkers in outpatient settings.

Screening sigmoidoscopy. Factors associated with utilization

Although screening sigmoidoscopy (SS) reduces colorectal cancer mortality, surveys indicate that fewer than half of primary care physicians routinely recommend SS and less than 10% of eligible patients receive this test. The purpose of this study was to explore barriers to compliance with SS through a cross-sectional survey of general medicine patients. Clinician advice, perceived benefit of the test, and having a family member who has had the test are associated with SS, while perceived pain is a barrier to compliance and can negate the positive effects of clinician advice. These factors can be targeted as part of efforts to improve compliance with SS.

Operative versus nonoperative treatment of Achilles tendon rupture. A prospective randomized study and review of the literature

One hundred eleven patients with acute rupture of the Achilles tendon were included in a prospective trial and randomly assigned to groups for operative (56 patients) or nonoperative (55 patients) treatment. All of the patients were followed with clinic evaluations at 4 months and 1 year after the rupture. The major complications in the operative treatment group were three reruptures and two deep infections as compared with seven reruptures, one second rerupture, and one extreme residual lengthening of the tendon in the nonoperative group. There were fewer minor complications in the nonoperative group than in the operative group. The operatively treated patients had a significantly higher rate of resuming sports activities at the same level, a lesser degree of calf atrophy, better ankle movement, and fewer complaints 1 year after the accident. The conclusion we reached through this randomized prospective study is that operative treatment of ruptured Achilles tendons is preferable, but nonoperative treatment is an acceptable alternative.

Disposition kinetics of disopyramide in human healthy volunteers described by an open three compartment model

Disposition kinetics of disopyramide was examined in an open randomised cross-over study in 8 healthy volunteers. Disopyramide was randomly administered as a single bolus injection (150 mg) over a period of 5 min. and as an infusion (28.2) mg/h to steady state. Disposition kinetics of disopyramide were most precisely described by an open three compartment model according to Akaike's information criteria. Significant positive correlations (0.909 +/- 0.04, P less than 0.05 (injection study); 0.787 +/- 0.11, P less than 0.05 (infusion study] were observed between total serum concentrations of disopyramide and renal clearance while no significant correlation could be demonstrated between free serum concentrations and renal clearance. This implies a constant value of unbound renal clearance. The results are consistent with non linear kinetics (mainly caused by the variable free fraction of the drug), when based on total serum concentrations. The disposition of unbound disopyramide, however seems to be linear (i.e. the kinetic parameters are independent of dose) in the bolus injection study. Total elimination clearance (free and total), volume of distribution and elimination half-life were significantly higher in the steady state experiment than in the bolus injection study.

[Traumatic rupture of the thoracic aorta]

A man aged 19 years sustained multiple injuries on account of deceleration. Radiography of the thorax revealed increase in width of the mediastinum. Aortography after 1 1/2 days revealed pseudocoarctation of the aorta corresponding to rupture of the aortic isthmus. This investigation should be undertaken on broad indications in patients with relevant injuries and increase in width of the mediastinum.

Elimination kinetics and urinary excretion of disopyramide in human healthy volunteers

Elimination kinetics and the renal handling of disopyramide was examined in 8 healthy volunteers. Approximately 50% of the administered disopyramide undergoes hepatic metabolism (metabolic clearance = 116.1 +/- 42.2 ml/min.), while the rest is excreted by the kidneys (renal clearance = 101.9 +/- 21.6 ml/min.). Total renal excretion rate of disopyramide was 0.676 +/- 0.188 mumol/min. and 0.258 +/- 0.029 mumol/min. was excreted by glomerular filtration leaving a net tubular secretion of 60% of the total renal elimination. A significant positive correlation was observed between total serum concentrations and renal clearance values of disopyramide while no significant correlation could be obtained between serum concentrations of the unbound drug and renal clearance values of disopyramide, implying a constant value of unbound renal clearance. Hepatic blood flow was significantly (P less than 0.005) decreased following disopyramide infusion.

Transhiatal esophagectomy without thoracotomy

Twenty patients with cancer of the esophagus and/or cardia underwent transmediastinal esophagectomy by blunt dissection without thoracotomy. Resection and reconstruction with gastroesophageal anastomosis was performed in a single stage in 13 cases. The tumor was nonresectable in seven cases, and instead a substernal bypass was performed. The technical maneuvers are described, and the results and possible advantages and disadvantages of the transhiatal method are discussed.

Displacement of lidocaine from human plasma proteins by disopyramide

Displacement from human plasma proteins of lidocaine by disopyramide was investigated in serum from nine patients receiving lidocaine treatment because of severe ventricular arrhythmias. From each patient disopyramide in concentrations of 5.9 and 14.7 mumol/l was added to three different serum concentrations of lidocaine and the displacement was examined. At a serum concentration of disopyramide of 14.7 mumol/l the percentage of unbound lidocaine increased from 30.4 +/- 0.2 to 36.3 +/- 0.2% (mean +/- S.E.M., P less than 0.001) at an average total serum concentration of lidocaine of 22.7 mumol/l. The study implies a stronger binding affinity of disopyramide than lidocaine to alpha-1-acid glycoprotein. We recommend caution when using disopyramide immediately after an infusion of lidocaine. With the dosage regimen used serum concentrations considerably above the suggested therapeutic level were achieved in the majority of patients.

The Ah phenotype. Survey of forty-eight rat strains and twenty inbred mouse strains

Forty-four inbred and four randombred rat strains and 20 inbred mouse strains were examined for their Ah phenotype by determining the induction of liver microsomal aryl hydrocarbon (benzo[a]pyrene) hydroxylase activity (EC 1.14.14.1) by intraperitoneal treatment with either beta-naphthoflavone or 3-methylcholanthrene. All 48 rat strains were found to be Ah-responsive. The maximally induced hydroxylase specific activities of the ALB/Pit, MNR/Pit, MR/Pit, SHR/Pit, and Sprague-Dawley strains were of the same order of magnitude as the basal hydroxylase specific activities of the ACI/Pit, F344/Pit, OKA/Pit, and MNR/N strains. Six of the 20 mouse strains were Ah-nonresponsive (i.e. lacking the normal induction response and presumably lacking detectable amounts of the Ah receptor). The basal hydroxylase specific activities of the BDL/N, NFS/N, STAR/N, and ST/JN mouse strains were more than twice as high as the maximally induced hydroxylase specific activity of the CBA/HT strain.--To date, 24 Ah-nonresponsive mouse strains have been identified, out of a total of 68 known to have been characterized. The reasons for not finding a single Ah-nonresponsive inbred rat strain--as compared with about one Ah-nonresponsive inbred mouse strain found for every three examined--remain unknown.

Structural gene products of the murine Ah complex. Differences in ontogenesis and glucosamine incorporation between liver microsomal cytochromes P1-450 and P-448 induced by polycyclic aromatic compounds

Antibodies against mouse-liver microsomal cytochromes P1-450 and P-448, two polycyclic aromatic inducible cytochromes, were previously developed [Negishi, M. and Nebert, D.W. (1979) J. Biol. Chem. 254, 11015-11023]. Liver microsomes from 3-methylcholanthrene-treated and phenobarbital-treated and control adult mice and 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated adult and fetal mice were examined. Immunoprecipitable radioactivity was measured, following labeling with pyridoxal phosphate/NaB[3H]4 or with 125I-labeled p-aminosulfobenzoic acid/NaNO2 in vitro or with [3H]leucine, [14C]glucosamine, or [32P]O4 in vivo. (a) Induction of cytochrome P1-450 occurs developmentally earlier in gestation than induction of cytochrome P-448 when the mother is treated with polycyclic aromatic compounds. (b) There appears to be a basal form of cytochrome P-448 but no cytochrome P1-450 in control liver microsomes; inducibility of cytochrome P-448 thus ranges between 5--12-fold, whereas that of P1-450 is infinite. (c) Phenobarbital pretreatment induces no detectable P1-450 or P-448. (d) P-448 appears to be either greater in concentration than P1-450 in the membrane or more exposed than P1-450 on the microsomal membrane surface. (e) By the radioimmunoassay methods used, 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced P1-450 and P-448 in Ah-nonresponsive mice are indistinguishable from those in Ah-responsive mice; this is true in both the fetus and the adult. (f) Compared with P-448 expression, the expression of P1-450 is more closely associated with 3-methylcholanthrene-induced aryl hydrocarbon hydroxylase activity, and these two structural gene products are apparently regulated independently. (g) P-448 but not P1-450 appears to be a glycoprotein. These data illustrate further differences between two forms of polycyclic aromatic-inducible P-450 in mouse liver. Neither P1-450 nor P-448 appears to be a phosphoprotein. Neither anti-(P1-450) nor anti-(P-448) precipitates any forms of liver microsomal P-450 from beta-naphthoflavone-treated adult rabbits and, conversely, anti-LM4 (the antibody to rabbit liver microsomal P-450 form 4) does not precipitate any forms of liver microsomal P-450 from 3-methylcholanthrene-treated C57BL/6N mice.

The murine Ah locus: in utero toxicity and teratogenesis associated with genetic differences in benzo[a]pyrene metabolism

Benzo[a]pyrene, at dose between 50 and 300 mg per kg body weight given at Day 7 or 10 of gestation, causes in utero toxicity and teratogenicity more so in genetically "responsive" C57BL/6 than in "nonresponsive" AKR inbred mice. With the use of AKR X (C57BL/6) (AKR)F1 and (C57BL/6) (AKR)F1 X AKR backcrosses, it was shown that allelic differences at the Ah locus in the fetus can be correlated with dysmorphogenesis. If the mother is nonresponsive (Ahd/Ahd), the Ahb/Ahd genotype in the fetus is associated with more stillborns and resorptions, decreased fetal weight, increased congenital anomalies, and enhanced P1-450-mediated covalent binding of BP metabolites to fetal protein and DNA, when compared with the Ahd/Ahd genotype in the fetus from the same uterus. If the mother is responsive (Ahb/Ahd), however, none of these parameters can be distinguished between Ahb/Ahd and Ahd/Ahd individuals in the same uterus, presumably because enhanced BP metabolism in maternal tissues and placenta cancels out these differences between individual fetuses. Of particular interest in our study is the fact that the mother and the father both must be of a particular genotype before differences in teratogenesis among fetuses (due to their genotype) will be expressed. These data might provide an example in attempting to explain clinically why only one child is affected with an apparent "drug-induced syndrome" although the mother has taken the same dose of the particular drug during each of numerous pregnancies.

The Ah locus: biochemical basis for genetic differences in brain tumor formation in mice

Allelic differences at the Ah locus are showen to exist in the mouse brain. This finding probably explains inbred mouse strain differences in polycyclic hydrocarbon tumorigenesis of the brain described more than 35 years ago and may be important in understanding the etiology of genetic differences in certain human intracranial neoplasms.

Ah locus: genetic differences in susceptibility to cataracts induced by acetaminophen

The Ahb/Ahb homozygous and the Ahb/Ahd heterozygous inbred mouse strains from the (C57BL/6)(DBA/2)F1 X DBA/2 backcross are genetically responsive to 3-methylcholanthrene. They both also develop, within 6 hours after a large intraperitoneal dose of acetaminophen, an irreversible opacity in the anterior portion of the lens. Such cataract formation does not occur in similarly treated nonresponsive inbred strains or nonresponsive Ahd/Ahd individuals from the same backcross. Differences in acetaminophen metabolism and toxicity are associated with the Ah locus in the mouse, and differences in heritability at the Ah locus exist in the human. Our ophthalmologic findings may be important clinically to certain patients receiving either a single large overdose of this drug or high doses over a long period.

Genetic differences in induction of cytosol reduced-NAD(P):menadione oxidoreductase and microsomal aryl hydrocarbon hydroxylase in the mouse

The stimulation of reduced-NAD(P):menadione oxidoreductase (EC 1.6.99.2) activity in liver cytosol is highly correlated with the stimulation of hepatic microsomal aryl hydrocarbon (benzo[a]pyrene) hydroxylase (EC 1.14.14.2) activity in 3-methylcholanthrene-, beta-naphthoflavone-, phenobarbital-, or pregnenolone-16alpha-carbonitrile-treated inbred C57BL/6N and DBA/2N mice and in eight other inbred strains treated with 3-methylcholanthrene. No oxidoreductase activity is detectable in mouse liver microsomes. Cytochrome c and 2,6-dichlorophenolindophenol are equally good electron acceptors for the oxidoreductase. There is no preferential in vitro inhibition of induced versus control oxidoreductase activities by either alpha-naphthoflavone or metyrapone. In 3-methylcholanthrene-treated F1 and F2 progeny and offspring from backcrosses between the F1 and either C57BL/6N or DBA/2N parent, however, there is not a strict correlation between induced or noninducible aryl hydrocarbon hydroxylase and oxidoreductase activities. 2,3,7,8-Tetrachlorodibenzo-p-dioxin, at doses (80 mug kg-1) sufficiently high to induce the hydroxylase almost as well in DBA/2N as in C57BL/6N mice, induces the oxidoreductase about 3-fold in C57BL/6N and less than 50% in DBA/2N mice. All the data are consistent with an hypothesis that two loci (Ox-1 and Ox-2) regulate oxidoreductase induction by 3-methylcholanthrene, that one of the genes is linked to the Ah locus (with an estimated recombination frequency between 2% and 23%), and that the other gene is not linked to the Ah locus. These experimental data might be useful in the protein activator hypothesis of the Britten-Davidson model for gene regulation.