Live-cell three-dimensional single-molecule tracking reveals modulation of enhancer dynamics by NuRD

To understand how the nucleosome remodeling and deacetylase (NuRD) complex regulates enhancers and enhancer-promoter interactions, we have developed an approach to segment and extract key biophysical parameters from live-cell three-dimensional single-molecule trajectories. Unexpectedly, this has revealed that NuRD binds to chromatin for minutes, decompacts chromatin structure and increases enhancer dynamics. We also uncovered a rare fast-diffusing state of enhancers and found that NuRD restricts the time spent in this state. Hi-C and Cut&Run experiments revealed that NuRD modulates enhancer-promoter interactions in active chromatin, allowing them to contact each other over longer distances. Furthermore, NuRD leads to a marked redistribution of CTCF and, in particular, cohesin. We propose that NuRD promotes a decondensed chromatin environment, where enhancers and promoters can contact each other over longer distances, and where the resetting of enhancer-promoter interactions brought about by the fast decondensed chromatin motions is reduced, leading to more stable, long-lived enhancer-promoter relationships.

Community Priority setting for Fetal Alcohol Spectrum Disorder Research in Australia

Introduction

Fetal Alcohol Spectrum Disorder (FASD) is a neurodevelopmental disorder caused by prenatal alcohol exposure (PAE). FASD research is a rapidly growing field that crosses multiple disciplines. To ensure research is relevant and meaningful for people living with FASD, their families, and the broader public there is a need to engage community members in setting priorities for research.

Objectives

Our primary objective was to formally identify the views of people living with FASD, their parents/caregivers, service providers, and the general community on the research priorities for FASD and alcohol use in pregnancy in Australia. Our secondary objective was to provide an overview of current research in the highest priority areas identified.

Methods

The approach for this study involved two community surveys and a consensus workshop, followed by a rapid literature review. Survey responses (n = 146) were collected and grouped using qualitative thematic analysis. The themes identified were then ranked in a second survey (n = 45). The 22 highest ranked themes were considered in a workshop with 21 community members, and consensus on the top ten priority areas was sought. The priority areas were grouped into conceptually similar topics and rapid literature reviews were undertaken on each.

Results

A diverse range of priorities was identified within key areas of prevention, diagnosis, and therapy. On request from participants, separate priority lists were developed by Aboriginal and non-Aboriginal participants.

Conclusion

There is need for a national network of researchers to take forward the research commenced by the Centre of Research Excellence, FASD Research Australia, in addressing community priorities.

Key Words

Community, priorities, FASD, rapid review, Australia.

What is the evidence for interactions between filaggrin null mutations and environmental exposures in the aetiology of atopic dermatitis? A systematic review

BACKGROUND

Epidemiological studies indicate that gene-environment interactions play a role in atopic dermatitis (AD).

OBJECTIVES

To review the evidence for gene-environment interactions in AD aetiology, focusing on filaggrin (FLG) loss-of-function mutations.

METHODS

A systematic search from inception to September 2018 in Embase, MEDLINE and BIOSIS was performed. Search terms included all synonyms for AD and filaggrin/FLG; any genetic or epidemiological study design using any statistical methods were included. Quality assessment using criteria modified from guidance (ROBINS-I and Human Genome Epidemiology Network) for nonrandomized and genetic studies was completed, including consideration of power. Heterogeneity of study design and analyses precluded the use of meta-analysis.

RESULTS

Of 1817 papers identified, 12 studies fulfilled the inclusion criteria required and performed formal interaction testing. There was some evidence for FLG-environment interactions in six of the studies (P-value for interaction ≤ 0·05), including early-life cat ownership, older siblings, water hardness, phthalate exposure, higher urinary phthalate metabolite levels (which all increased AD risk additional to FLG null genotype) and prolonged breastfeeding (which decreased AD risk in the context of FLG null genotype). Major limitations of published studies were the low numbers of individuals (ranging from five to 94) with AD and FLG loss-of-function mutations and exposure to specific environmental factors, and variation in exposure definitions.

CONCLUSIONS

Evidence on FLG-environment interactions in AD aetiology is limited. However, many of the studies lacked large enough sample sizes to assess these interactions fully. Further research is needed with larger sample sizes and clearly defined exposure assessment. Linked Comment: Park and Seo. Br J Dermatol 2020; 183:411.

Guidelines for Perioperative Care in Bariatric Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations

BACKGROUND

During the last two decades, an increasing number of bariatric surgical procedures have been performed worldwide. There is no consensus regarding optimal perioperative care in bariatric surgery. This review aims to present such a consensus and to provide graded recommendations for elements in an evidence-based "enhanced" perioperative protocol.

METHODS

The English-language literature between January 1966 and January 2015 was searched, with particular attention paid to meta-analyses, randomised controlled trials and large prospective cohort studies. Selected studies were examined, reviewed and graded. After critical appraisal of these studies, the group of authors reached a consensus recommendation.

RESULTS

Although for some elements, recommendations are extrapolated from non-bariatric settings (mainly colorectal), most recommendations are based on good-quality trials or meta-analyses of good-quality trials.

CONCLUSIONS

A comprehensive evidence-based consensus was reached and is presented in this review by the enhanced recovery after surgery (ERAS) Society. The guidelines were endorsed by the International Association for Surgical Metabolism and Nutrition (IASMEN) and based on the evidence available in the literature for each of the elements of the multimodal perioperative care pathway for patients undergoing bariatric surgery.

Robust metastable skyrmions and their triangular-square lattice structural transition in a high-temperature chiral magnet

Skyrmions, topologically protected nanometric spin vortices, are being investigated extensively in various magnets. Among them, many structurally chiral cubic magnets host the triangular-lattice skyrmion crystal (SkX) as the thermodynamic equilibrium state. However, this state exists only in a narrow temperature and magnetic-field region just below the magnetic transition temperature T_c, while a helical or conical magnetic state prevails at lower temperatures. Here we describe that for a room-temperature skyrmion material, β-Mn-type Co ₈Zn ₈Mn ₄, a field-cooling via the equilibrium SkX state can suppress the transition to the helical or conical state, instead realizing robust metastable SkX states that survive over a very wide temperature and magnetic-field region. Furthermore, the lattice form of the metastable SkX is found to undergo reversible transitions between a conventional triangular lattice and a novel square lattice upon varying the temperature and magnetic field. These findings exemplify the topological robustness of the once-created skyrmions, and establish metastable skyrmion phases as a fertile ground for technological applications.

Emergent Interacting Spin Islands in a Depleted Strong-Leg Heisenberg Ladder

Properties of the depleted Heisenberg spin ladder material series (C_{7}H_{10}N)_{2}Cu_{1-z}Zn_{z}Br_{4} have been studied by the combination of magnetic measurements and neutron spectroscopy. Disorder-induced degrees of freedom lead to a specific magnetic response, described in terms of emergent strongly interacting "spin island" objects. The structure and dynamics of the spin islands is studied by high-resolution inelastic neutron scattering. This allows us to determine their spatial shape and to observe their mutual interactions, manifested by strong spectral in-gap contributions.

Synbiotic consumption changes the metabolism and composition of the gut microbiota in older people and modifies inflammatory processes: a randomised, double-blind, placebo-controlled crossover study

BACKGROUND

Ageing can result in major changes in the composition and metabolic activities of bacterial populations in the large gut and an impaired immune system.

AIM

To investigate the effects of synbiotic consumption on the colonic microbiota, immune function and health status in older people.

METHODS

A randomised, double-blind placebo-controlled, 4-week crossover study was carried out, involving 43 older volunteers, using a synbiotic comprising the probiotic Bifidobacterium longum and an inulin-based prebiotic Synergy 1 (SudZucker, Mannheim, Germany). Faecal and blood samples were collected, and clinical status scored at the start, and at 2- and 4-week intervals, with a 4-week washout between each feeding period. Faecal bacteria were determined by fluorescent in situ hybridisation. Short-chain fatty acid concentrations, cytokine production, bowel habit and a range of clinical parameters were measured.

RESULTS

The synbiotic increased bifidobacterial numbers by 1.4 log units (P < 0.0001) and also increased members of the phyla Actinobacteria and Firmicutes (P = 0.0004, P < 0.0001). Proteobacteria were reduced by 1.0 log units (P < 0.0001). Synbiotic feeding was associated with increased butyrate production (P = 0.0399). The pro-inflammatory response was modified by the synbiotic, with significantly reduced pro-inflammatory cytokine TNF-α in peripheral blood after 2 and 4 weeks of synbiotic consumption (P = 0.02, P = 0.0406). The synbiotic had no effect on bowel habit or any clinical parameters.

CONCLUSION

Short-term synbiotic use can be effective in improving the composition and metabolic activities of colonic bacterial communities and immune parameters in older people. This study was registered at clinicaltrials.gov as NCT01226212.

Clinical trial: the microbiological and immunological effects of synbiotic consumption - a randomized double-blind placebo-controlled study in active Crohn's disease

BACKGROUND

Crohn's disease is an inflammatory illness in which the immune response against gut microorganisms is believed to drive an abnormal immune response. Consequently, modification of mucosal bacterial communities, and the immune effects they elicit, might be used to modify the disease state.

AIM

To investigate the effects of synbiotic consumption on disease processes in patients with Crohn's disease.

METHODS

A randomized, double-blind placebo-controlled trial was conducted involving 35 patients with active Crohn's disease, using a synbiotic comprising Bifidobacterium longum and Synergy 1. Clinical status was scored and rectal biopsies were collected at the start, and at 3- and 6-month intervals. Transcription levels of immune markers and mucosal bacterial 16S rRNA gene copy numbers were quantified using real-time PCR.

RESULTS

Significant improvements in clinical outcomes occurred with synbiotic consumption, with reductions in both Crohn's disease activity indices (P = 0.020) and histological scores (P = 0.018). The synbiotic had little effect on mucosal IL-18, INF-gamma and IL-1beta; however, significant reductions occurred in TNF-alpha expression in synbiotic patients at 3 months (P = 0.041), although not at 6 months. Mucosal bifidobacteria proliferated in synbiotic patients.

CONCLUSION

Synbiotic consumption was effective in improving clinical symptoms in patients with active Crohn's disease.

Crohn's Disease Incidence in NHS Tayside

Background & Aims

The incidence of Crohn's disease (CD) in northeastern Scotland was last reported as rising in the 1980's, while in the rest of Europe it had reached steady state. This study reviewed the incidence of CD in NHS Tayside.

Methods

Data was collected retrospectively and analysed using age and sex standardization, socioeconomic factors and urban and rural postcodes.

Results

A point prevalence of 157 per 100,000 population in the Tayside region was found. The average incidence of CD was 9.56 per 100,000 per year between 2003 and 2007 and 7.16 per 100,000 per year between 1998 and 2001. There was no link to urbanization and no difference in incidence between the sexes. Incidence was not related to affluence in this population and peak age of onset occurred in the third decade of life only. 12.7% of patients had a family history of inflammatory bowel disease and 25% of patients were current smokers.

Conclusions

The incidence of CD appears to have arrived at a steady state in Tayside, while recent evidence suggests that it is on the rise in Scandinavia again. The results of the genetic studies to come from the east of Scotland are eagerly awaited to help shed light on the aetiology of this complex disorder.

Two-dimensional coherence for measurement of asymmetry in postural steadiness

Two-dimensional magnitude squared coherence (2D-MSC) is developed to compare the two-valued time series which represent the center of pressure (COP) under each foot. A sinusoidal multiple taper spectral estimator is used to reduce bias and improve spectral resolution. The measure is applied to evaluate symmetry in the dual-plate postural steadiness time series obtained from healthy young and elderly volunteers, and patients with Huntington's Disease (HD), a group in which asymmetries in postural steadiness are anticipated. The results demonstrate that the 2D-MSC is a robust measure of inter-limb coordination that may be of value in studies of aging and neurologic disease.

The association between coeliac disease and cardiovascular disease

BACKGROUND

Coeliac disease is more prevalent than was previously thought. The association between coeliac disease and cardiovascular outcome is not clear.

AIM

To investigate whether coeliac disease patients have an increased risk of cardiovascular events.

METHODS

A community-based cohort study using a record-linkage database. Three hundred and sixty-seven coeliac patients identified by a positive antiendomysial antibody test or a diagnosis with small bowel biopsy, and 5537 subjects who were tested and had a negative coeliac immunology, were included in the study.

RESULTS

The crude rates of cardiovascular events were 9.5 per 1000 person-years (95% CI: 4.4-14.6) in the coeliac cohort and 8.9 per 1000 person-years (95% CI: 7.6-10.3) in the antiendomysial antibody-negative cohort. Compared with the antiendomysial antibody-negative cohort, the adjusted relative risk of cardiovascular events for coeliac cohort was 1.9 (95% CI: 1.00-3.60). When we excluded patients who had previous hospitalization for cardiovascular disease, the adjusted relative risk was 2.5 (95% CI: 1.22-5.01). The use of any cardiovascular drugs prior to and after entry to the study were 36% and 29% for the coeliac cohort (P = 0.05), and 34% and 26% for the antiendomysial antibody-negative cohort (P < 0.01).

CONCLUSION

Our findings suggest that coeliac disease seems to be associated with an increased risk of cardiovascular outcome.

Strategies for self-management of HIV-related anxiety

This study examines the frequency and effectiveness of commonly used strategies for self management of anxiety in an international sample of 502 participants from Norway (n=42, 8%), Taiwan (n=35, 7%), and the US (n=426, 85%). An activities checklist summarized into five categories of self-care behaviours including activities/thoughts, exercise, medications, complementary therapies, and substance use determined self-care behaviours. Ratings of frequency and effectiveness for each self-care activity were also included. Praying received the highest overall rating of effectiveness of any self-management strategies included in this study at 8.10 (scale 1 to 10), followed by meditation (7.37), exercising (7.32), using relaxation techniques (7.22), cooking (6.98), and walking (6.90). An analysis of effectiveness scores for each self-care strategy by country reflected a wide variation. The three most effective anxiety self-care strategies reported by participants from Norway included exercise (7.31), walking (6.96), and reading (6.44). Highest ratings of effectiveness by participants from Taiwan included talking with others with HIV (6.0), attending support groups (6.0), and exercising (6.0). US participants allocated highest ratings of effectiveness to complementary/alternative therapies, including praying (8.10), meditating (7.43), and using relaxation techniques (7.35). Regardless of the country, watching television and talking with family and friends were the two most frequently reported strategies. These strategies for self-management of HIV-related anxiety are important for clinicians to be aware of in the care of persons with HIV/AIDS.

The role of the Lumina intense pulsed light system in the treatment of port wine stains—a case controlled study

The pulsed dye laser has been the treatment of choice for port wine stains over the past 20 years. In the past 5 years there has been increasing discussion of the role of other light treatments, such as the intense pulsed light system in the treatment of port wine stains. These systems use high-energy lamps, which emit noncoherent broad-spectrum light. Cut off filters are applied depending on the treatment modality to limit the wavelengths emitted. We present the results of a 3-year prospective within patient controlled clinical trial using an intense pulsed light system called the Lumina, developed by Lynton Lasers of Cheshire, England. Our aims and objectives were to assess the effectiveness of the system in the treatment of port wine stains in a human model and to record the optimum treatment parameters and the incidence of side effects. Following ethical approval 12 subjects were enrolled into the trial. In order to meet the requirements of the local ethics committee these were all adults with port wine stains located in less visible areas of the body. The results showed that eight of the 12 subjects had some degree of fading of their port wine stain as measured on a percentage scoring system. Of the four who failed to show any response, all had pink port wine stains. It did seem the case that the darker the port wine stain, the better the fading seen. Furthermore, the more distal lesions tended to be less responsive than those situated closer to the head area. However, it is difficult to draw any definitive statistical conclusions due to the small number of patients in the trial.

Fatal human rabies caused by European bat Lyssavirus type 2a infection in Scotland

We wish to report the first recorded case of indigenous human rabies caused by a bat bite in the United Kingdom in 100 years. This instructive case report highlights a number of key lessons: first, bites from insectivorous bats indiginous to the United Kingdom can cause rabies in humans; second, rabies immunization is essential for bat-handlers, and postexposure treatment for rabies is essential for patients bitten by bats; third, patients able to give a history who present with acute flaccid paralysis and/or presumptive viral encephalitis should be asked if they have been bitten by bats, irrespective of travel history, or this history should be obtained from family or friends; fourth, antemortem diagnosis of bat rabies (EBLV type 2a infection) in humans is possible using RT-PCR.

Nodal metastatic melanoma in the neck of a 4-year-old girl after diagnosis of Spitz nevus of the cheek

A 4-year-old girl was referred to the plastic surgery unit with metastatic malignant melanoma diagnosed in a cervical lymph node. She had previously undergone excision of a Spitz nevus of the cheek at age 18 months. The management of this patient is discussed along with a review of the literature relating to Spitz nevi and malignant melanoma in childhood.

Sandostatin LAR (long-acting octreotide acetate) for malignant carcinoid syndrome: a 3-year experience

BACKGROUND

Somatostatin analogues are the best therapy for controlling the symptoms of malignant carcinoid syndrome. Octreotide acetate given as subcutaneous injection up to three times daily, intramuscular Lanreotide injection given once per 1-2 weeks and monthly intramuscular Sandostatin LAR have demonstrated similar efficacy in short-term studies.

AIM

To assess the long-term effect of Sandostatin LAR on the management of patients with malignant carcinoid syndrome.

METHODS

This was a 3-year retrospective study. Twenty-seven patients were assessed with a median follow-up of 23 months. Thirteen patients were switched from subcutaneous octreotide and 14 patients were octreotide naive. All patients showed avid uptake on indium-111 octreotide imaging.

RESULTS

Ten of the 13 patients previously on subcutaneous octreotide and 13 of the 14 patients who were octreotide naive had good symptom control on Sandostatin LAR. Over the period of follow-up, many patients showed progression of their tumour and required additional therapies. Patients expressed a preference for monthly intramuscular Sandostatin LAR as opposed to daily subcutaneous injections of octreotide. Although Sandostatin LAR was difficult to administer in certain instances, overall it was well tolerated.

CONCLUSIONS

Sandostatin LAR provides good long-term symptomatic control in patients with malignant carcinoid syndrome; it is well tolerated and patients expressed improved satisfaction in their management.

Eight years' experience of gastrostomy tube management

BACKGROUND AND STUDY AIMS

Increasingly, patients fed by gastrostomy tube are surviving the lifespan of the device. Data are scarce concerning the factors affecting the longevity and failure of gastrostomy tubes or the criteria for selection of replacement devices which leads to cost-effective patient management. The aims of the study were: to set criteria for selection of replacement gastrostomy tubes; to determine the causes of gastrostomy tube failure, and the factors affecting device longevity; and to examine the effect of initiating an educational programme for caregivers on resource utilization in long-term enteral nutrition patients.

MATERIALS AND METHODS

We analyzed the clinical gastrostomy tube database compiled prospectively over 8 years by the nutrition team at Ninewells Hospital, Dundee.

RESULTS

For 363 gastrostomy tubes inserted in 304 patients (160 women; median age 71), the median duration of gastrostomy tube use was 138 days. The total follow-up was 294 patient-years. Death occurred before the first gastrostomy tube replacement in 48 % of patients, but 20 % resumed oral nutrition. Tube failure mechanisms were: dislodgment, 28 %; perishing of tube material, 25 %; tube-related Candida albicans infection, 16 %; leakage, 7 %; and unspecified, 7 %. Of the balloon tubes and gastrostomy buttons, 8 % needed early replacement due to dislodgment and/or leakage. The cost per day for replacement percutaneous endoscopic gastrostomy (PEG) was Euro 2.12, for balloon tubes it was Euro 0.62, and for gastrostomy buttons Euro 1.80. Despite an increasing PEG insertion rate throughout the study period, yearly referrals for PEG-related problems dropped by 30 % between 1997 to 1999, coinciding with the initiation of an educational programme for caregivers.

CONCLUSION

Tube longevity is mainly limited by the patient's diagnosis and prognosis. The choice of replacement device should be based on clinical factors. The use of more durable materials in the manufacture of gastrostomy tubes may prolong tube life and reduce cost. Education of patients and caregivers by a multidisciplinary nutrition support team promotes independence and limits demand on the service.

Dental fluorosis: variability among different inbred mouse strains

Concurrent with the decline in dental caries has been an increase in the prevalence of dental fluorosis, a side-effect of exposure to greater than optimal levels of fluoride during amelogenesis. The mechanisms that underlie the pathogenesis of dental fluorosis are not known. We hypothesize that genetic determinants influence an individual's susceptibility or resistance to develop dental fluorosis. We tested this hypothesis using a mouse model system (continuous eruption of the incisors) where genotype, age, gender, food, housing, and drinking water fluoride level can be rigorously controlled. Examination of 12 inbred strains of mice showed differences in dental fluorosis susceptibility/resistance. The A/J mouse strain is highly susceptible, with a rapid onset and severe development of dental fluorosis compared with that in the other strains tested, whereas the 129P3/J mouse strain is least affected, with minimal dental fluorosis. These observations support the contribution of a genetic component in the pathogenesis of dental fluorosis.

Use of a carbon dioxide laser in the treatment of multiple epidermoid cysts

We treated a 41-year-old woman for multiple epidermoid cysts to the face using a carbon dioxide laser. The management and its rationale are discussed.

Body fluid shifts in soldiers after a jogging/walking exercise in the heat: effects of water and electrolyte solution on rehydration

OBJECTIVES

To examine the relationships between dehydration and body fluid shifts and the effects of ingesting water or oral rehydration solution or no fluid during and after exercise in the heat [mean (SE)] temperature, 40.5 (0.66) degrees C and 32 (3.7)% humidity.

DESIGN

PRE and POST three hours exercise comparative study.

SETTING

Zimbabwe National Army Wafa-Wafa Training Camp, Kariba, Zimbabwe.

SUBJECTS

18 male soldiers volunteered to be studied during and after a 20 km (three hour) jogging/walking exercise in full kit.

MAIN OUTCOME MEASURES

Body mass, total body water, extracellular water, intracellular water, plasma osmolality, plasma sodium, and volume changes compared using paired t-test.

RESULTS

Total body water decreased by 4.9 (0.38) 1 (p < 0.02) in soldiers exercising without fluid, 1.5 (0.3) 1 (oral rehydration solution), 2.4 (0.8) 1 (water). Extracellular water decreased by 3.6 (0.3) 1 (p < 0.05), 1.3 (0.2) 1, 1.7 (0.3) 1, and intracellular water decreased by 1.3 (0.1) 1, 0.2 (0.01) 1, 0.7 (0.01) 1 respectively in these groups. Plasma volume decreased by [mean (SE)] 16 (1.4)% on no fluid, three (0.3)% on oral rehydration solution, five (0.3)% on water. Plasma osmolality increased significantly from 285 (1.0) to 301 (2.3) mosmol.kg-1 (p < 0.001) in subjects exercising without fluid and from 283 (2.0) to 291 (0.7) mosmol.kg-1 (p < 0.02) in subjects taking oral rehydration solution. No significant increases were observed when taking water only.

CONCLUSIONS

During dehydration, total body water loss was derived from both fluid compartments but extracellular water contributed the most. Effective rehydration depends on adequate replacement of electrolytes lost from each fluid compartment. Water alone may not provide adequate rehydration.

Acute respiratory distress syndrome among trauma patients: trends in ICU mortality, risk factors, complications and resource utilization

OBJECTIVE

To evaluate trends in mortality and related factors among trauma patients who developed acute respiratory distress syndrome (ARDS).

STUDY

Observational study based on data prospectively gathered in computerized trauma registry.

SETTING

Trauma intensive care unit (ICU) of 48 beds in level I trauma center.

PATIENTS

All trauma patients with ARDS admitted during 1985-87 (486, group 1 [G1]) and 1993-95 (552, group 2[G2]).

METHODS

ARDS was defined by American-European Consensus Conference criteria and the need for 48 h or more on mechanical ventilation with FIO2 greater than 0.50 and PEEP of more than 5 cmH2O. Demographics, severity score, injury-admission delay time, first 24-h transfusion and septic and organ system failure complications were independent variables. ICU mortality was the dependent variable. ICU length of stay (LOS) and life support techniques were considered. Respiratory and renal support strategies were different in the two time periods.

RESULTS

Mortality decreased over the period (G1: 29.2% vs G2: 21.4%, p < 0.04), in patients aged both over and under 65 years. Multivariate analysis showed mortality was related to age, severity and time period (G1 1.68-fold that in G2) and that the greater G1 mortality was related to more renal failure and hematologic failure/dysfunction. ICU LOS decreased from 31.7+/-26.7 days (G1) to 27.3+/-22 days (G2) (p < 0.003).

CONCLUSIONS

Mortality among trauma patients with ARDS declined over the 8 years studied and was associated with less organ failure. This reduction was probably the result of new approaches to mechanical ventilation, renal failure replacement and vasoactive drug therapy.