How nature can exploit nonspecific catalytic and carbohydrate binding modules to create enzymatic specificity

Noncatalytic carbohydrate binding modules (CBMs) are components of glycoside hydrolases that attack generally inaccessible substrates. CBMs mediate a two- to fivefold elevation in the activity of endo-acting enzymes, likely through increasing the concentration of the appended enzymes in the vicinity of the substrate. The function of CBMs appended to exo-acting glycoside hydrolases is unclear because their typical endo-binding mode would not fulfill a targeting role. Here we show that the Bacillus subtilis exo-acting β-fructosidase SacC, which specifically hydrolyses levan, contains the founding member of CBM family 66 (CBM66). The SacC-derived CBM66 (BsCBM66) targets the terminal fructosides of the major fructans found in nature. The crystal structure of BsCBM66 in complex with ligands reveals extensive interactions with the terminal fructose moiety (Fru-3) of levantriose but only limited hydrophobic contacts with Fru-2, explaining why the CBM displays broad specificity. Removal of BsCBM66 from SacC results in a ∼100-fold reduction in activity against levan. The truncated enzyme functions as a nonspecific β-fructosidase displaying similar activity against β-2,1– and β-2,6–linked fructans and their respective fructooligosaccharides. Conversely, appending BsCBM66 to BT3082, a nonspecific β-fructosidase from Bacteroides thetaiotaomicron, confers exolevanase activity on the enzyme. We propose that BsCBM66 confers specificity for levan, a branched fructan, through an “avidity” mechanism in which the CBM and the catalytic module target the termini of different branches of the same polysaccharide molecule. This report identifies a unique mechanism by which CBMs modulate enzyme function, and shows how specificity can be tailored by integrating nonspecific catalytic and binding modules into a single enzyme.     

Early-phase pelvic bone SPECT: Simulation and comparison of several acquisition protocols to reduce bladder artifact and improve image quality

Tomoscintigraphic reconstruction in nuclear medicine assumes that the distribution of the tracer is unchanged in the volume of interest throughout the duration of the acquisition. This condition is however not met in early-phase bone scintigraphy and early-phase pelvic SPECT may display helical artifacts due to the filling of the bladder. Those artifacts may hamper proper interpretation of surrounding bone areas. The aim of this study was to construct a 4D digital pelvic phantom to simulate different acquisition protocols and optimize the acquisition.A 4D digital pelvic phantom was generated with a dynamic component consisting in an expanding bladder with 2 ureters and a static part consisting in the 2 kidneys, bone structures, and soft tissues. Projection data were obtained using an attenuated Radon transform function. Four acquisitions protocols were tested: 32 projections of 16 seconds (32–16–1), 32 projections of 8 seconds (32–8–1), 2 consecutive SPECT of 32 projections of 4 seconds (32–4–2) and 2 consecutive SPECT of 16 projections of 8 seconds (16–8–2). The optimal protocol was then tested on one patient.The amplitude of the artifacts was reduced with the 32–8–1, 32–4–2, and 16–8–2 protocols. The 16–8–2 protocol had the highest signal to noise ratio among those 3 protocols. The bladder artifact was visually markedly reduced on the patient acquisition with a 16–8–2 protocol.Two successive early-phase bone SPECT, with a lower number of projection than the usual protocol reduce the impact of the helical artifacts around the bladder.     

Noninferiority and equivalence designs: issues and implications for mental health research

The terms noninferiority and equivalence are often used interchangeably to refer to trials in which the primary objective is to show that a novel intervention is as effective as the standard intervention. The use of these designs is becoming increasingly relevant to mental health research. Despite the fundamental importance of these designs, they are often poorly understood, improperly applied, and subsequently misinterpreted. In this article, the authors explain noninferiority and equivalence designs and key methodological and statistical considerations. Decision points in using these designs are discussed, such as choice of control condition, determination of the noninferiority margin, and calculation of sample size and power. With increasing utilization of these designs, it is critical that researchers understand the methodological issues, advantages, disadvantages, and related challenges.     

Metachronous Wilms tumor associated with pulmonary embolism: how can we detect these cases early? A case report and literature review

A 4-year-old girl developed right metachronous Wilms tumor 2 years after completing treatment for a left-sided stage I Wilms tumor. The original treatment included 7 weeks of chemotherapy, delayed nephrectomy, and another 3 weeks of chemotherapy. The metachronous tumor on the right side extended into the inferior vena cava and right atrium. She developed pulmonary embolism as a result. She received chemotherapy and developed liquifaction of the tumor and toxic shock. She also had surgery. The patient is alive 3 years after the original diagnosis and 10 months after the relapse. The authors report this unusual case and discuss whether these cases can be identified early.     

Fifty years of paediatric malignant bone tumours in the West Midlands,UK, 1957–2006: incidence,treatment and outcome

Parkes SE, Parke S, Manghan DC, Grimer RJ, Davies P, Morland BJ. Fifty years of paediatric malignant bone tumours in the West Midlands, UK, 1957–2006: incidence, treatment and outcome. Paediatric and Perinatal Epidemiology 2010. Malignant bone tumours in the paediatric age group (0–14 years) are uncommon; various aetiological theories exist and few reports of incidence, age and sex distributions have been published. We examined the incidence of childhood malignant bone tumours in one large single region of the UK over an extended period of 50 years. The West Midlands specialist regional children's tumour registry holds data on all malignancies and benign brain tumours in children under 15 years in the West Midlands region, which has a population of around 1 million children. Demographic and clinical data have been abstracted and diagnoses reviewed by a panel of expert pathologists. During the period 1957–2006, 259 cases of malignant paediatric bone tumours were diagnosed. There were 153 osteosarcomas, 78 Ewing sarcomas and 28 other primary bone tumours. The overall age standardised rate was 4.66, with no increase over time, although there was a significant increase in the incidence of Ewing sarcomas in the period 1965–92. Sixty‐eight per cent of tumours were in patients over 10 years, whereas the incidence in patients under 10 years showed a non‐significant increase. Survival rates increased dramatically post‐chemotherapy introduction, with Ewing sarcoma demonstrating better survival overall. This is a large study giving an overview of malignant bone tumours in the childhood population of a single region over an extended period, showing results consistent with national reports. It also examines late effects, which were mostly mobility/orthopaedic, although almost one‐fifth of patients had cardiac problems and five went on to develop second malignancies.     

Disruptions to human speed perception induced by motion adaptation and transcranial magnetic stimulation

To investigate the underlying nature of the effects of transcranial magnetic stimulation (TMS) on speed perception, we applied repetitive TMS (rTMS) to human V5/MT+ following adaptation to either fast‐ (20 deg/s) or slow (4 deg/s)‐moving grating stimuli. The adapting stimuli induced changes in the perceived speed of a standard reference stimulus moving at 10 deg/s. In the absence of rTMS, adaptation to the slower stimulus led to an increase in perceived speed of the reference, whilst adaptation to the faster stimulus produced a reduction in perceived speed. These induced changes in speed perception can be modelled by a ratio‐taking operation of the outputs of two temporally tuned mechanisms that decay exponentially over time. When rTMS was applied to V5/MT+ following adaptation, the perceived speed of the reference stimulus was reduced, irrespective of whether adaptation had been to the faster‐ or slower‐moving stimulus. The fact that rTMS after adaptation always reduces perceived speed, independent of which temporal mechanism has undergone adaptation, suggests that rTMS does not selectively facilitate activity of adapted neurons but instead leads to suppression of neural function. The results highlight the fact that potentially different effects are generated by TMS on adapted neuronal populations depending upon whether or not they are responding to visual stimuli.     

European collaboration in trials of new agents for children with cancer

Childhood cancer is a relatively rare disease, representing just 1% of all malignancies. Within Europe, this represents some 12,000 new cases each year, with approximately 1600 a year in the United Kingdom and 1800 in France. International collaboration in phase III trials of childhood cancer has been the norm for many years, traditionally within Europe, but, largely because of organisational considerations, phase I and II trials have only been conducted on a national basis. With overall cure rates in the region of 70%, relatively few children are available for these early drug trials. Access to new drugs is also a major problem. Against this background, a United Kingdom (UK)/French 'new agent' collaboration was established, expanding subsequently into a wider European grouping. This paper documents the history of that collaboration, the outcomes and future challenges.     

Cerebellum/liver index in pretherapeutic 18F-FDG PET/CT as a predictive marker of progression-free survival in follicular lymphoma treated by immunochemotherapy and rituximab maintenance

The purpose of this study was to investigate the value of the “cerebellum/ liver index for prognosis” (CLIP) as a new prognostic marker in pretherapeutic ¹⁸F-Fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) in patients with follicular lymphoma treated by immunochemotherapy and rituximab maintenance, focusing on progression-free survival (PFS).Clinicobiological and imaging data from patients with follicular lymphoma between March 2010 and September 2015 were retrospectively collected and 5-year PFS was determined. The conventional PET parameters (maximum standardized uptake value and total metabolic tumor volume) and the CLIP, corresponding to the ratio of the cerebellum maximum standardized uptake value over the liver SUVmean, were extracted from the pretherapeutic ¹⁸F-FDG PET.Forty-six patients were included. Eighteen patients (39%) progressed within the 5 years after treatment initiation. Five-year PFS was 78.6% when CLIP was >4.0 and 42.0% when CLIP was <4.0 (P = .04). CLIP was a significant predictor of PFS on univariate analysis (hazard ratio 3.1, P = .049) and was near-significant on multivariate analysis (hazard ratio 2.8, P = .07) with ECOG PS as a cofactor.The CLIP derived from pretherapeutic ¹⁸F-FDG PET seems to be an interesting predictive marker of PFS in follicular lymphoma treated by immunochemotherapy and rituximab maintenance. These results should be evaluated prospectively in a larger cohort.     

Induction toxicity of a modified Memorial Sloan-Kettering-New York II protocol in children with relapsed acute lymphoblastic leukemia: A single institution study

Although the chance of cure for children with acute lymphoblastic leukaemia (ALL) is high, their outlook with subsequent relapse is poor. Bone marrow transplantation may be an option for some, but the need for intensive reinduction chemotherapy regimens remains the best hope for effecting cure in the majority of relapsed children. The authors report the experience of using an intensive chemotherapy protocol (Memorial Sloan-Kettering-New York II Protocol, MSK-NY-II) in a series of relapsed children with ALL. Thirty children presenting to the Royal Alexandra Hospital for Children, Sydney, in their first relapse of ALL were treated according to a modification of the original MSK-NY-II protocol. Three children (10%) died during induction therapy, two from overwhelming Gram-negative sepsis, and one from intracerebral haemorrhage. Of 27 children completing induction, two children failed to enter remission; however, both had planned deviations from the protocol. Infectious complications were prominent with a total of 55 admissions for febrile neutropenic episodes. Eight children required the support of the intensive care unit for infectious complications. A total of 36 microbiological isolates were obtained from the patients during induction therapy. Ten bone marrow transplant procedures have been subsequently performed in these children, of whom five are alive and disease free at the time of writing. The MSK-NY-II protocol is an intensive regimen but with encouraging early remission rates in relapsed childhood ALL. Early sepsis in previously immunosuppressed children is an important cause of induction death. © 1996 Wiley-Liss, Inc.