Acute myeloid leukemia transforms the bone marrow niche into a leukemia-permissive microenvironment through exosome secretion.

Little is known about how leukemia cells alter the bone marrow (BM) niche to facilitate their own growth and evade chemotherapy. Here, we provide evidence that acute myeloid leukemia (AML) blasts remodel the BM niche into a leukemia growth-permissive and normal hematopoiesis-suppressive microenvironment through exosome secretion. Either engrafted AML cells or AML-derived exosomes increased mesenchymal stromal progenitors and blocked osteolineage development and bone formation in vivo. Preconditioning with AML-derived exosomes 'primed' the animals for accelerated AML growth. Conversely, disruption of exosome secretion in AML cells through targeting Rab27a, an important regulator involved in exosome release, significantly delayed leukemia development. In BM stromal cells, AML-derived exosomes induced the expression of DKK1, a suppressor of normal hematopoiesis and osteogenesis, thereby contributing to osteoblast loss. Conversely, treatment with a DKK1 inhibitor delayed AML progression and prolonged survival in AML-engrafted mice. In addition, AML-derived exosomes induced a broad downregulation of hematopoietic stem cell-supporting factors (for example, CXCL12, KITL and IGF1) in BM stromal cells and reduced their ability to support normal hematopoiesis. Altogether, this study uncovers novel features of AML pathogenesis and unveils how AML cells create a self-strengthening leukemic niche that promotes leukemic cell proliferation and survival, while suppressing normal hematopoiesis through exosome secretion.

Diagnostic challenges in patients with bleeding phenotype and von Willebrand exon 28 polymorphism p.D1472H.

Exon 28 polymorphism p.D1472H is associated with significantly lower von Willebrand Ristocetin cofactor activity (VWF:RCoF) to von Willebrand antigen (VWF:Ag) ratio compared to normal, but has been reported as not conferring haemorrhagic risk. The impact of this polymorphism while assessing symptomatic patients for von Willebrand disease (VWD) has not been previously analysed. We retrospectively reviewed charts of children with clinically significant bleeding and abnormal VW panel who underwent VW exon 28 analysis. Twenty-three of 63 patients studied had p.D1472H. Of these 23 patients, 6 with borderline low VWF:RCo were given provisional diagnosis of VWD type 1 by treating physicians, which could be alternatively explained as due to the effect of p.D1472H. None of the patients with low VWF:RCo, decreased VWF:RCo/VWF:Ag ratio and p.D1472H had VWD type 2M mutations identified. This study illustrates the challenge in diagnosing VWD using ristocetin-based VW assay in symptomatic patients with p.D1472H.

Three-dimensional patient setup errors at different treatment sites measured by the Tomotherapy megavoltage CT.

BACKGROUND AND PURPOSE: Reduction of interfraction setup uncertainty is vital for assuring the accuracy of conformal radiotherapy. We report a systematic study of setup error to assess patients' three-dimensional (3D) localization at various treatment sites. PATIENTS AND METHODS: Tomotherapy megavoltage CT (MVCT) images were scanned daily in 259 patients from 2005-2008. We analyzed 6,465 MVCT images to measure setup error for head and neck (H&N), chest/thorax, abdomen, prostate, legs, and total marrow irradiation (TMI). Statistical comparisons of the absolute displacements across sites and time were performed in rotation (R), lateral (x), craniocaudal (y), and vertical (z) directions. RESULTS: The global systematic errors were measured to be less than 3 mm in each direction with increasing order of errors for different sites: H&N, prostate, chest, pelvis, spine, legs, and TMI. The differences in displacements in the x, y, and z directions, and 3D average displacement between treatment sites were significant (p < 0.01). Overall improvement in patient localization with time (after 3-4 treatment fractions) was observed. Large displacement (> 5 mm) was observed in the 75(th) percentile of the patient groups for chest, pelvis, legs, and spine in the x and y direction in the second week of the treatment. CONCLUSION: MVCT imaging is essential for determining 3D setup error and to reduce uncertainty in localization at all anatomical locations. Setup error evaluation should be performed daily for all treatment regions, preferably for all treatment fractions.

Platelet adhesion to multimerin 1 in vitro: influences of platelet membrane receptors, von Willebrand factor and shear.

BACKGROUND: Multimerin 1 (MMRN1) is a large, homopolymeric adhesive protein, stored in platelets and endothelium, that when released, binds to activated platelets, endothelial cells and the extracellular matrix. OBJECTIVES: The goals of our study were to determine if (i) MMRN1 supports adhesion of resting and/or activated platelets under conditions of blood flow, and (ii) if MMRN1 enhances platelet adhesion to types I and III collagen. PATIENTS/METHODS: Platelet adhesion was evaluated using protein-coated microcapillaries, with or without added adhesive proteins and receptor antibodies. Platelets from healthy controls, Glanzmann thrombasthenia (GT) and severe von Willebrand factor (VWF)-deficient donors were tested. RESULTS: MMRN1 supported the adhesion of activated, but not resting, washed platelets over a wide range of shear rates. At low shear (150 s(-1)), this adhesion was supported by integrins alphavbeta3 and glycoprotein (GP) Ibalpha but it did not require integrins alphaIIbbeta3 or VWF. At high shear (1500 s(-1)), adhesion to MMRN1 was supported by beta3 integrin-independent mechanisms, involving GPIbalpha and VWF, that did not require platelet activation when VWF was perfused over MMRN1 prior to platelets. MMRN1 bound to types I and III collagen, independent of VWF, however, its enhancing effects on platelet adhesion to collagen at high shear were VWF dependent. CONCLUSIONS: MMRN1 supports platelet adhesion by VWF-dependent and -independent mechanisms that vary by flow rate. Additionally, MMRN1 binds to, and enhances, platelet adhesion to collagen. These findings suggest that MMRN1 could function as an adhesive ligand that promotes platelet adhesion at sites of vascular injury.

Cutaneous melanoma: a population-based epidemiology report with 989 patients in Hong Kong.

Studies in white populations have confirmed advanced age as a risk factor for cutaneous melanoma, but in nonwhite populations, its role is less clear. To clarify a possible association in our local population, comprising 94.9% Chinese, a retrospective epidemiological study of 20 years of data on cutaneous melanoma between 1983 and 2002 from a central cancer registry in Hong Kong was conducted. There were 989 new cases and 378 death cases registered, and analysis showed that both the incidence and mortality rate of cutaneous melanoma increase with increasing age. Advanced age is thus confirmed as a risk factor for cutaneous melanoma in our local population. In an ageing population, the estimated future incidence and mortality rate of cutaneous melanoma are likely to increase.

Intrauterine lignocaine as an anaesthetic during endometrial sampling: a randomised double-blind controlled trial.

OBJECTIVE: To evaluate the effectiveness of intrauterine lignocaine as an anaesthetic during endometrial sampling. DESIGN: Prospective, randomised, double-blind, placebo-controlled trial. SETTING: Outpatient gynaecological minor operation unit in a public hospital. POPULATION: Two hundred premenopausal women scheduled for endometrial sampling because of abnormal uterine bleeding. METHODS: Transcervical intrauterine instillation of 5 mL of 2% lignocaine or 5 mL of normal saline before performing endometrial sampling with vacuum aspirator. MAIN OUTCOME MEASURES: Evaluation of pain associated with the procedure using a visual analogue scale. RESULTS: The use of intrauterine lignocaine reduced pain during suction curettage in endometrial sampling. CONCLUSIONS: Transcervical instillation of lignocaine reduced pain during endometrial sampling.

Quality assurance of a helical tomotherapy machine.

Helical tomotherapy has been developed at the University of Wisconsin, and 'Hi-Art II' clinical machines are now commercially manufactured. At the core of each machine lies a ring-gantry-mounted short linear accelerator which generates x-rays that are collimated into a fan beam of intensity-modulated radiation by a binary multileaf, the modulation being variable with gantry angle. Patients are treated lying on a couch which is translated continuously through the bore of the machine as the gantry rotates. Highly conformal dose-distributions can be delivered using this technique, which is the therapy equivalent of spiral computed tomography. The approach requires synchrony of gantry rotation, couch translation, accelerator pulsing and the opening and closing of the leaves of the binary multileaf collimator used to modulate the radiation beam. In the course of clinically implementing helical tomotherapy, we have developed a quality assurance (QA) system for our machine. The system is analogous to that recommended for conventional clinical linear accelerator QA by AAPM Task Group 40 but contains some novel components, reflecting differences between the Hi-Art devices and conventional clinical accelerators. Here the design and dosimetric characteristics of Hi-Art machines are summarized and the QA system is set out along with experimental details of its implementation. Connections between this machine-based QA work, pre-treatment patient-specific delivery QA and fraction-by-fraction dose verification are discussed.

Does sweeping of membranes beyond 40 weeks reduce the need for formal induction of labour?

OBJECTIVE: To assess the efficacy of sweeping of membranes beyond 40 weeks of gestation in reducing the incidence of induction of labour, when induction was planned at 42 weeks. DESIGN: Prospective randomised controlled trial. SETTING: A regional obstetric unit in Hong Kong. POPULATION AND METHODS: A total of 120 women with certain gestational age, determined by early pregnancy ultrasound scan, were recruited from 1st July, 1998 to 31st December, 1999. Sixty women were randomly allocated to sweeping of membranes and the other 60 women acted as control. The satisfaction for women allocated to sweeping of membranes was assessed by a questionnaire after the procedure. The two groups were assessed on intention-to-treat basis. MAIN OUTCOME MEASURES: The incidence of formal induction of labour was compared between the two groups. Possible complications of sweeping of membranes such as rupture of membranes, intrapartum infection, postpartum infection, and neonatal infection were also assessed. Maternal and perinatal outcomes were also assessed. RESULTS: The recruitment to delivery interval was significantly shorter among women who had sweeping of membranes (3.2 versus 4.2 days, P < 0.05). The incidence of induction of labour was comparable (35.5% versus 38%, RR 0.91, 95% CI 0.57 - 1.46). The incidences of caesarean section and assisted vaginal delivery were comparable. The incidences of premature rupture of membranes, intrapartum, and postpartum infection were comparable. The perinatal outcomes were also comparable between the two groups. Up to 70% of women found that this procedure was associated with significant discomfort. One third of these women complained of significant pain. CONCLUSIONS: Sweeping of membranes beyond 40 weeks does not reduce the need for formal induction of labour at 42 weeks. Although it is safe, the majority of women felt uncomfortable during the procedure.

Spontaneous uterine perforation of pyometra. A report of three cases.

BACKGROUND: Spontaneous perforation of pyometra is a rare cause of generalized peritonitis; only 17 cases have been reported. CASES: Three cases of spontaneous perforation of pyometra occurred; two were associated with carcinoma of the cervix. All were treated with exploratory laparotomy and drainage. The first patient died of recurrent carcinoma of the cervix five months after laparotomy. The second patient died of septic shock shortly after the operation. The third patient made a good postoperative recovery. CONCLUSION: Pyometra is a serious medical condition, because of both its association with malignant disease and the danger of spontaneous perforation, which carries significant morbidity and mortality. Although rare, ruptured pyometra should be considered in the differential diagnosis of acute abdomen in elderly women, especially those with malignant disorders of the genital tract. The treatment of pyometra rupture is immediate laparotomy, peritoneal lavage and drainage, or simple hysterectomy.