A patient questionnaire for radiation-induced brachial plexopathy

We analyzed the usefulness of a symptom questionnaire to screen for radiation-induced brachial plexopathy (RIBP) after breast cancer treatment. Four questions addressed distal and proximal paresis: impaired hand functions, problems raising the arm, carrying weights, and lifting objects from a high shelf. Eighty-one relapse-free patients were neurologically examined. Treatment was mastectomy (51%) or breast-conserving surgery (49%), radiotherapy to the supraclavicular +/- axilla with median 60 Gy maximum dose. Sixty-five subsequent control patients had breast-conserving surgery and radiotherapy to the breast only with 55 Gy median dose. Median follow up was 10 and 7.4 years, respectively. Sixteen patients had RIBP, 7 had Radiation Therapy Oncology Group (RTOG) grade 1, 4 grade 2, 3 grade 3, and 2 grade 4 RIBP. Thirty-seven patients had fibrosis and 32 had arm edema. Four patients with RIBP had no fibrosis (n = 2) or fibrosis of the axilla only (n = 2). Specificity of the question "impaired hand functions" for RIBP was 0.66 (95% confidence interval [CI], 0.51-0.78); sensitivity was 0.80 (95% CI, 0.52-0.96). Specificity of the question "raising the arm" was 0.98 (95% CI, 0.9-0.99) and sensitivity was 0.18 (95% CI, 0.04-0.45); the rate of false-positive control patients was 3%. In multivariate analysis, "impaired hand functions" and fibrosis were independent indicators of RIBP (P <0.005). Patients with breast irradiation only stated moderate/pronounced impaired hand functions; and problems carrying weights and lifting objects from a high shelf in 38%, 58%, and 77%, not significantly different from patients with RIBP or the patients with supraclavicular radiation. RIBP is not necessarily associated with fibrosis. The aim of the questionnaire was screening of a population at risk for RIBP. In this group, the question "problems raising the arm" detected severe RIBP with high specificity. Negation of "impaired hand functions" excludes RIBP. Both questions should be included in follow-up questionnaires.     

Novel mutations of APOB cause ApoB truncations undetectable in plasma and familial hypobetalipoproteinemia

Familial hypobetalipoproteinemia (FHBL) is a genetic disorder characterized by low levels of apoB-100 and LDL cholesterol. Truncation-producing mutations of apoB (chromosome 2) are among several potential causes of FHBL in patients. Ten new families with FHBL linked to chromosome 2 were identified. In Family 8, a 4432delT in exon 26 produces a frame-shift and a premature stop codon predicted to produce a truncated apoB-30.9. Even though this truncation is just 10 amino acid shorter than the well-documented apoB-31, which is readily detectable in plasma, apoB-30.9 is undetectable. Most truncations shorter than apoB-30 are not detectable in plasma. In Family 34, an acceptor splicing mutation at position -1 of exon 14 changes the acceptor splice site AG to AA. Two families (Family 50 and 52) had mutations (apoB-9 and apoB-29) reported previously. In Family 98, a novel point mutation in exon 26 (11163T>G) causes a premature stop codon, and produces a truncated apoB-80.5 readily detectable in plasma. Sequencing of the ApoB gene in families 1, 5, 18, 58, and 59 did not reveal mutations.     

Pharmacokinetics of diltiazem and its metabolites in relation to CYP2D6 genotype

OBJECTIVES: Recently, it was shown in vitro that the polymorphic enzyme cytochrome P450 (CYP) 2D6 mediates O-demethylation of diltiazem. The aim of this study was to compare the pharmacokinetics of diltiazem and its major metabolites in healthy human volunteers representing different CYP2D6 genotypes. METHODS: Norwegians of Caucasian origin were screened for their CYP2D6 genotype on the LightCycler (Roche Diagnostics, Mannheim, Germany) by melting-curve analysis of allele-specific fluorescence resonance energy transfer probes hybridized to polymerase chain reaction-amplified deoxyribonucleic acid. The first 5 individuals identified with genotypes corresponding to a homozygous extensive, heterozygous extensive, or homozygous poor CYP2D6-metabolizing phenotype, respectively, were voluntarily enrolled in the pharmacokinetic study. The participants received diltiazem, 120 mg, as a single oral dose, and plasma samples were collected up to 24 hours after administration. Plasma samples were purified by solid phase extraction. Diltiazem and 7 phase I metabolites were analyzed by liquid chromatography-mass spectrometry. RESULTS: The pharmacokinetics of diltiazem was not significantly different between the subgroups. However, the systemic exposure of the pharmacologically active metabolites desacetyl diltiazem and N-demethyldesacetyl diltiazem was > or = 5 times higher in poor CYP2D6 metabolizers than in extensive CYP2D6 metabolizers (P <.01). CONCLUSIONS: CYP2D6 activity does not have a major impact on the disposition of diltiazem. In contrast, desacetyl diltiazem and N-demethyldesacetyl diltiazem are markedly accumulated in individuals expressing a deficient CYP2D6 phenotype. Because these metabolites exhibit pharmacologic properties of possible importance, individual CYP2D6 activity might be an aspect to consider in the clinical use of diltiazem.     

Iatrogenic FDG foci in the lungs: a pitfall of PET image interpretation

Ohne Zusammenfassung     

Prevention of lung allograft rejection by combined treatment with adhesion molecule antibodies and cyclosporine

Infiltration of leukocytes into the lung allograft is regulated by adhesion molecules during acute rejection. The purpose of this study was to assess the effect of monoclonal antibodies against ICAM-1 (1A29) to prevent rejection after lung transplantation. Left lateral orthotopic lung transplantation was performed using Dark Agouti rats as donors and Lewis rats as recipients. Recipients received 1A29 alone (group A), cyclosporine A alone (group B), a combination of both drugs (group C) or no therapy (group D). Animals were killed on day 5 and 10, respectively. Rejection was graded by histology. Myeloperoxidase activity (MPO) was measured in the graft. In allografts treated with cyclosporine and 1A29 histologically a lower grade of rejection was seen and less MPO were detected compared to groups A, B and D. Anti-ICAM-1 monoclonal antibodies alone as well as a subtherapeutic dose of cyclosporine are not effective to prevent acute allograft rejection after lung transplantation. However, the combination of both strategies significantly reduces rejection in this model.     

Bile acids in serum and bile of infants with cholestatic syndromes

The concentration of individual bile acids in serum was measured in 18 neonates and infants with various cholestatic conditions (extrahepatic biliary atresia, neonatal hepatitis syndrome, chronic intrahepatic cholestasis and posthemolytic cholestasis). The cholate/chenodeoxycholate ratio in serum was smaller than one in all patients with neonatal hepatitis syndrome or extrahepatic biliary atresia, cholestatic conditions which were accompanied by signs of liver cell injury. It was greater than one in the patients with chronic intrahepatic cholestasis. Administration of cholestyramine to patients with patent extrahepatic bile ducts decreased the total concentration bile acids in serum and elevated the cholate/chenodeoxycholate ratio. Thus, cholestyramine administration may be of diagnostic value for evaluation of bile duct patency in cholestasis of infancy. Differences between the bile acid pattern in serum and bile were observed. Thus, the cholate/chenodeoxycholate ratio was always higher in bile than in serum. 3beta-hydroxy-5-cholenoic acid found in serum was not detectable in bile. This finding suggests that impairment of biliary excretion rather than increased hepatic synthesis is responsible for elevation of this monohydroxy bile acid in serum.     

Comparative pharmacokinetics of sulphasalazine and sulphapyridine after rectal and oral administration to patients with ulcerative colitis

Summary Rectal administration of sulphasalazine to patients with ulcerative colitis has recently been shown to have similar therapeutic activity but fewer side effects than oral treatment. The present study is a comparison of the pharmacokinetics of sulphasalazine (SASP) and its metabolite sulphapyridine (SP) after rectal and oral administration of SASP to 6 patients with ulcerative colitis. The areas under the concentration-time curves (AUC) and the maximum concentrations (C_max) of SASP and SP were significantly lower after rectal than oral administration of SASP (p<0.05). These findings support the view that the lower frequency of side effects after rectal administration of SASP may result from the lower plasma levels of SASP and SP.     

Assay of Total Plasma Apolipoprotein B Concentration in Human Subjects

We have developed a double antibody radioimmunoassay (RIA) for human apolipoprotein B (ApoB). The assay measures not only the ApoB content of beta-lipoproteins (low density lipoproteins [LDL]) but also that contained in the other lipoproteins in plasma.Purified lymph and plasma chylomicrons and plasma very low density lipoproteins (VLDL) produced displacement curves in the assay system which paralleled those produced by pure LDL. Thus, the ApoB found in chylomicrons, VLDL, and LDL were immunologically identical. ApoB accounted for about 25 and 35%, respectively, of the total protein of chylomicrons and VLDL by RIA. VLDL and LDL preparations from normal and hyperlipoproteinemic subjects also produced parallel displacement curves, suggesting that the ApoB of normal and hyperlipoproteinemic subjects were immunologically identical. High density lipoproteins and abetalipoproteinemic plasma displaced no counts, nor did the sera of several animal species produce any useful displacement curves in this system.The fasting total plasma ApoB concentration of normal subjects was 83+/-16 mg/dl (mean+/-SD). ApoB levels were high in Type II (162+/-16), and less so in Type IV (112+/-24) and Type V (105+/-17).When plasma ApoB concentration in Type IV patients was graphed against plasma glycerides, two subpopulations, which may represent different genetic or biochemical subgroups, were apparent.ApoB concentration in individuals on constant diet and drug regimen was stable over weeks to months. Greater than 90% of ApoB of normal and Type II subjects was in the d > 1.006 plasma fraction. By contrast, only 50-80% of ApoB was in the d > 1.006 fraction in Types IV and V. Thus, hypertriglyceridemia was associated primarily with a redistribution of ApoB to the lighter density fractions; by contrast, in hypercholesterolemia absolute ApoB concentration was markedly increased.     

Bicycle exercise stress in PET for assessment of coronary flow reserve: repeatability and comparison with adenosine stress.

PET allows absolute measurements of myocardial blood flow (MBF). The aim of the present study was to evaluate the feasibility and repeatability of supine bicycle exercise stress, compared with standard adenosine stress, in PET. METHODS: In 11 healthy volunteers, MBF was assessed at rest, during adenosine-induced (140 microg/kg/min over 7 min) hyperemia, and immediately after supine bicycle exercise (mean workload, 130 W, which is 70% of the predicted value) using PET and (15)O-H(2)O. The assessment was then repeated after 20 min. Coronary flow reserve (CFR) was calculated as hyperemic/resting MBF for adenosine stress and exercise stress. Repeatability was evaluated according to the method of Bland and Altman. RESULTS: No significant differences were found between the paired resting MBF (1.22 +/- 0.16 vs. 1.26 +/- 0.21 mL/min/g; mean difference, 3% +/- 11%) and the hyperemic MBF with adenosine stress (5.13 +/- 0.74 vs. 4.97 +/- 1.05; mean difference, -4% +/- 14%) or exercise stress (2.35 +/- 0.66 vs. 2.25 +/- 0.61; mean difference, -4% +/- 19%). CFR was reproducible with adenosine stress (4.23 +/- 0.62 vs. 4.05 +/- 1.06, P = not statistically significant; mean difference, -5% +/- 19%) and exercise stress (1.91 +/- 0.46 vs. 1.80 +/- 0.44, P = not statistically significant; mean difference, -5% +/- 15%). Repeatability coefficients for MBF were 0.26 (rest), 1.34 (adenosine stress), and 0.82 (exercise stress) mL/min/g. CONCLUSION: Assessment of CFR with (15)O-H(2)O and PET using bicycle exercise in the PET scanner is feasible and at least as repeatable as using adenosine stress.     

Impact of human D398N single nucleotide polymorphism on intracellular calcium response mediated by α3β4α5 nicotinic acetylcholine receptors

The human CHRNA5 D398N polymorphism (rs16969968) causes an aspartic acid to asparagine change in the nicotinic acetylcholine receptor (nAChR) α5 subunit gene. The N398 variant of CHRNA5 is linked to increased risk for nicotine dependence. In this study, we explored the effect of the CHRNA5 D398N polymorphism on the properties of human α3β4* nicotinic acetylcholine receptors in human embryonic kidney (HEK) cells. Addition of either D398 or N398 variant of α5 subunit in the α3β4* receptor did not affect total [(125)I]-epibatidine binding or surface expression of the receptor. However, addition of α5(D398) into α3β4* receptor decreased the maximal response to agonist without significantly affecting EC(50) in aequorin intracellular calcium assay. α3β4α5(N398) nAChRs showed further decreased maximal response. The differences in agonist efficacy between the receptor subtypes were found to be dependent upon the concentration of external calcium but independent of external sodium. Moreover, activation of α3β4α5 nAChRs led to significantly greater intracellular calcium release from IP(3) stores relative to α3β4 nAChRs although no effect of the α5 polymorphism was observed. Finally, inclusion of the α5 variant caused a small shift to the left in IC(50) for some of the antagonists tested, depending upon α5 variant but did not affect sensitivity of α3β4* receptors to desensitization in response to incubation with nicotine. In conclusion, addition of either variant of α5 into an α3β4α5 receptor similarly effects receptor pharmacology and function. However, the N398 variant exhibits a reduced response to agonists when extracellular calcium is high and it may lead to distinct downstream cellular signaling.