Sequencing a mouse acute promyelocytic leukemia genome reveals genetic events relevant for disease progression

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML). It is characterized by the t(15;17)(q22;q11.2) chromosomal translocation that creates the promyelocytic leukemia-retinoic acid receptor α (PML-RARA) fusion oncogene. Although this fusion oncogene is known to initiate APL in mice, other cooperating mutations, as yet ill defined, are important for disease pathogenesis. To identify these, we used a mouse model of APL, whereby PML-RARA expressed in myeloid cells leads to a myeloproliferative disease that ultimately evolves into APL. Sequencing of a mouse APL genome revealed 3 somatic, nonsynonymous mutations relevant to APL pathogenesis, of which 1 (Jak1 V657F) was found to be recurrent in other affected mice. This mutation was identical to the JAK1 V658F mutation previously found in human APL and acute lymphoblastic leukemia samples. Further analysis showed that JAK1 V658F cooperated in vivo with PML-RARA, causing a rapidly fatal leukemia in mice. We also discovered a somatic 150-kb deletion involving the lysine (K)-specific demethylase 6A (Kdm6a, also known as Utx) gene, in the mouse APL genome. Similar deletions were observed in 3 out of 14 additional mouse APL samples and 1 out of 150 human AML samples. In conclusion, whole genome sequencing of mouse cancer genomes can provide an unbiased and comprehensive approach for discovering functionally relevant mutations that are also present in human leukemias.     

Regional- and agonist-dependent facilitation of human neurogastrointestinal functions by motilin receptor agonists

BACKGROUND AND PURPOSE

Delayed gastric emptying is poorly managed. Motilin agonists are potential treatments but inadequate understanding into how enteric nerve functions are stimulated compromises drug/dose selection. Resolution is hampered by extreme species dependency so methods were developed to study human gastrointestinal neuromuscular activities and the neurobiology of motilin.

EXPERIMENTAL APPROACH

Protocols to study neuromuscular activities were developed for different regions of human stomach and intestine (71 patients) using circular muscle preparations and electrical field stimulation (EFS) of intrinsic nerves. Other tissues were fixed for immunohistochemistry.

KEY RESULTS

EFS evoked contractions and/or relaxations via cholinergic and nitrergic neurons, with additional tachykinergic activity in colon; these were consistent after 154 min (longer if stored overnight). Motilin 1–300 nM and the selective motilin agonist GSK962040 0.1–30 µM acted pre-junctionally to strongly facilitate cholinergic contractions of the antrum (E_max≍ 1000% for motilin), with smaller increases in fundus, duodenum and ileum; high concentrations increased baseline muscle tension in fundus and small intestine. There were minimal effects in the colon. In the antrum, cholinergic facilitation by motilin faded irregularly, even with peptidase inhibitors, whereas facilitation by GSK962040 was long lasting. Motilin receptor immunoreactivity was identified in muscle and myenteric plexus predominantly in the upper gut, co-expressed with choline acetyltransferase in neurons.

CONCLUSIONS AND IMPLICATIONS

Motilin and GSK962040 strongly facilitated cholinergic activity in the antrum, with lower activity in fundus and small intestine only. Facilitation by motilin was short lived, consistent with participation in migrating motor complexes. Long-lasting facilitation by GSK962040 suggests different receptor interactions and potential for clinical evaluation.

LINKED ARTICLE

This article is commented on by Depoortere, pp. 760–762 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2012.02046.x     

Pregnancy loss rates after midtrimester amniocentesis

OBJECTIVE: The purpose of this study was to quantify the contemporary procedure-related loss rate after midtrimester amniocentesis using a database generated from patients who were recruited to the First And Second Trimester Evaluation of Risk for Aneuploidy trial. METHODS: A total of 35,003 unselected patients from the general population with viable singleton pregnancies were enrolled in the First And Second Trimester Evaluation of Risk for Aneuploidy trial between 10 3/7 and 13 6/7 weeks gestation and followed up prospectively for complete pregnancy outcome information. Patients who either did (study group, n=3,096) or did not (control group, n=31,907) undergo midtrimester amniocentesis were identified from the database. The rate of fetal loss less than 24 weeks of gestation was compared between the two groups, and multiple logistic regression analysis was used to adjust for potential confounders. RESULTS: The spontaneous fetal loss rate less than 24 weeks of gestation in the study group was 1.0% and was not statistically different from the background 0.94% rate seen in the control group (P=.74, 95% confidence interval -0.26%, 0.49%). The procedure-related loss rate after amniocentesis was 0.06% (1.0% minus the background rate of 0.94%). Women undergoing amniocentesis were 1.1 times more likely to have a spontaneous loss (95% confidence interval 0.7-1.5). CONCLUSION: The procedure-related fetal loss rate after midtrimester amniocentesis performed on patients in a contemporary prospective clinical trial was 0.06%. There was no significant difference in loss rates between those undergoing amniocentesis and those not undergoing amniocentesis. LEVEL OF EVIDENCE: II-2.     

A Descriptive Study of the Risk Factors Associated With Catheter‐Related Bloodstream Infections in the Home Parenteral Nutrition Population

Background: Home parenteral nutrition (HPN) is increasingly used for nutrition support after patients are discharged from the hospital. Catheter‐related bloodstream infections (CR‐BSI) are a common and potentially fatal complication of HPN. The risk factors for development of CR‐BSI in the outpatient setting are poorly understood. Methods: We conducted an observational, retrospective study of 225 patients discharged from Barnes‐Jewish Hospital on HPN between January 1, 2007, and December 31, 2009. HPN complications were defined as any cause that led to either premature discontinuation of HPN therapy or catheter replacement. CR‐BSI events were identified by provider documentation. We calculated the overall complication rate and the complication rate specifically due to CR‐BSI. Backward stepwise Cox regression analyses were used to assess for independent predictors of catheter‐related complications. Results: In total, 111 of 225 patients (49%) developed complications while receiving HPN (incidence = 5.06 episodes/1000 catheter days). Sixty‐eight of 225 patients (30%) required catheter removal for CR‐BSI (incidence = 3.10 episodes/1000 catheter days). Independent predictors of line removal specifically due to infection included anticoagulant use, ulcer or open wound, and Medicare or Medicaid insurance. The following risk factors were associated with catheter‐associated complications and/or CR‐BSI: the presence of ulcers, the use of systemic anticoagulants, public insurance (Medicare or Medicaid), and patient age. Independent predictors of line removal for any complication included age and anticoagulant use. Conclusion: Catheter‐related complications were extremely common in patients receiving HPN. Healthcare providers caring for individuals who require HPN should be aware of risk factors for complications.     

Clinical pharmacology and primary health care in Europe — a gap to bridge

Summary A group of senior European clinical pharmacologists presents a position paper on the possible role of clinical pharmacology (CP) in bridging the gap between academic drug evaluation and drug prescribing in primary health care (PHC). As a teaching, research and service discipline CP has developed in academic or other major hospitals while 80% of all drugs are prescribed in PHC. CP therefore has to extend its functions to PHC. Examples are given of how joint ventures between clinical pharmacologists and PHC physicians may improve the quality of drug research and increase the clinical relevance of drug information in PHC, thereby contributing towards rational drug utilization in PHC. Colleagues in PHC are invited to respond to this call for collaboration.Professors Melander and Wesseling hold positions as primary health care oriented clinical pharmacologists     

A new method for isolating Trypanosoma brucei gambiense from sleeping sickness patients

Low infectivity to laboratory mammals and low virulence make Trypanosoma brucei gambiense difficult to isolate and grow in amounts sufficient for biochemical characterization. We report the isolation of T.b. gambiense by feeding cryopreserved primary isolates to laboratory-reared Glossina morsitans morsitans, followed by rapid cultivation in vitro of procyclic forms dissected from infected tsetse fly midguts. This technique allows the characterization of hitherto unsampled populations and avoids selection due to long-term subpassage. Of 16 primary isolates from trypanosomiasis patients of the Fontem focus in Cameroon, 12 (75%) produced infections in tsetse whereas only 4 (25%) infected rats. Ten isolates were subsequently cultivated as procyclic forms in vitro; 2 failed to grow owing to bacterial contamination. In addition, 2 primary isolates from C?te d'Ivoire patients and a stock of low virulence from the Congo Republic were similarly grown. Only one primary isolate produced tsetse salivary gland infections, an observation consistent with the hypothesis that some populations of T.b. gambiense are intrinsically incompatible with G.m. morsitans.     

Extrachromosomal inheritance of susceptibility to trypanosome infection in tsetse flies. II. Susceptibility of selected lines of Glossina morsitans morsitans to different stocks and species of trypanosome

Two lines of Glossina m. morsitans, selected for susceptibility and refractoriness to infection with a single stock of Trypanosoma congolense, have now been shown to be susceptible or refractory to different stocks of T. congolense and, also, to different stocks of T. b. brucei and T. b. gambiense. The mean midgut infection rates of the susceptible line obtained in different experiments with T. congolense, T. b. brucei and T. b. gambiense were, respectively, 66%, 56% and 55%; the corresponding mature (hypopharynx or salivary gland) infection rates were 37%, 23% and 0%. The highest mature infection rates obtained in individual experiments with susceptible flies were 65% (T. congolense) and 40% (T. b. brucei). Mean T. congolense and T. b. brucei midgut infection rates obtained with the refractory line were 29% and 33% respectively, the mature infection rates being 12% and 7%, all significantly lower than the corresponding rates in the susceptible line. Development of midgut infections in susceptible flies appears to take place irrespective of trypanosome stock or form. There is some evidence to suggest that higher infection rates can be obtained with flies infected and maintained on mammals rather than on in vitro feeding systems. Susceptible flies matured a significantly greater proportion of their midgut T. congolense and T. b. brucei infections than did the refractory line, which suggests that maturation of infections is influenced by the susceptibility status of the fly. However, the apparent inability of these flies to develop mature infections of a major T. b. gambiense genetic grouping suggests that maturation of infections established in the midgut is a phenomenon primarily associated with trypanosome genotype.     

Effect of chronically administered ketoconazole on the elimination of theophylline in man

Ketoconazole, a nitrogen-substituted imidazole, has been shown to be a potent in vitro inhibitor of cytochrome P-450-mediated metabolic processes. Conflicting reports exist concerning the in vivo effect of ketoconazole on concomitantly administered drugs that require these metabolic processes for clearance. Therefore, the effect of multiple-dose ketoconazole on the elimination of theophylline, a drug metabolized by cytochrome P-450, in ten healthy, nonsmoking males (aged 18-40 years) was evaluated. Each subject received aminophylline 6 mg/kg iv before and at the end of seven days of ketoconazole 200 mg/d po. Theophylline serum concentrations were determined by fluorescence polarization immunoassay (TDx) at 12 time points over the 24-hour period following each infusion. No statistical difference (two-tailed t-test) in half-life (mean +/- SD 7.8 +/- 1.8 vs. 8.2 +/- 1.9 h) or clearance (0.797 +/- 0.201 vs. 0.722 +/- 0.133 ml/min/kg) could be demonstrated for theophylline before or after ketoconazole administration. Theophylline dosage adjustment is probably not necessary for concomitant theophylline and ketoconazole drug therapy.