Experimental laboratory models as tools for understanding modifiable dementia risk

Experimental laboratory research has an important role to play in dementia prevention. Mechanisms underlying modifiable risk factors for dementia are promising targets for dementia prevention but are difficult to investigate in human populations due to technological constraints and confounds. Therefore, controlled laboratory experiments in models such as transgenic rodents, invertebrates and in vitro cultured cells are increasingly used to investigate dementia risk factors and test strategies which target them to prevent dementia. This review provides an overview of experimental research into 15 established and putative modifiable dementia risk factors: less early-life education, hearing loss, depression, social isolation, life stress, hypertension, obesity, diabetes, physical inactivity, heavy alcohol use, smoking, air pollution, anesthetic exposure, traumatic brain injury, and disordered sleep. It explores how experimental models have been, and can be, used to address questions about modifiable dementia risk and prevention that cannot readily be addressed in human studies. HIGHLIGHTS: Modifiable dementia risk factors are promising targets for dementia prevention. Interrogation of mechanisms underlying dementia risk is difficult in human populations. Studies using diverse experimental models are revealing modifiable dementia risk mechanisms. We review experimental research into 15 modifiable dementia risk factors. Laboratory science can contribute uniquely to dementia prevention.

Development of a smartphone screening test for preclinical Alzheimer's disease and validation across the dementia continuum

BACKGROUND

Dementia prevalence is predicted to triple to 152 million globally by 2050. Alzheimer's disease (AD) constitutes 70% of cases. There is an urgent need to identify individuals with preclinical AD, a 10-20-year period of progressive brain pathology without noticeable cognitive symptoms, for targeted risk reduction. Current tests of AD pathology are either too invasive, specialised or expensive for population-level assessments. Cognitive tests are normal in preclinical AD. Emerging evidence demonstrates that movement analysis is sensitive to AD across the disease continuum, including preclinical AD. Our new smartphone test, TapTalk, combines analysis of hand and speech-like movements to detect AD risk. This study aims to [1] determine which combinations of hand-speech movement data most accurately predict preclinical AD [2], determine usability, reliability, and validity of TapTalk in cognitively asymptomatic older adults and [3], prospectively validate TapTalk in older adults who have cognitive symptoms against cognitive tests and clinical diagnoses of Mild Cognitive Impairment and AD dementia.

METHODS

Aim 1 will be addressed in a cross-sectional study of at least 500 cognitively asymptomatic older adults who will complete computerised tests comprising measures of hand motor control (finger tapping) and oro-motor control (syllabic diadochokinesis). So far, 1382 adults, mean (SD) age 66.20 (7.65) years, range 50-92 (72.07% female) have been recruited. Motor measures will be compared to a blood-based AD biomarker, phosphorylated tau 181 to develop an algorithm that classifies preclinical AD risk. Aim 2 comprises three sub-studies in cognitively asymptomatic adults: (i) a cross-sectional study of 30-40 adults to determine the validity of data collection from different types of smartphones, (ii) a prospective cohort study of 50-100 adults ≥ 50 years old to determine usability and test-retest reliability, and (iii) a prospective cohort study of ~1,000 adults ≥ 50 years old to validate against cognitive measures. Aim 3 will be addressed in a cross-sectional study of ~200 participants with cognitive symptoms to validate TapTalk against Montreal Cognitive Assessment and interdisciplinary consensus diagnosis.

DISCUSSION

This study will establish the precision of TapTalk to identify preclinical AD and estimate risk of cognitive decline. If accurate, this innovative smartphone app will enable low-cost, accessible screening of individuals for AD risk. This will have wide applications in public health initiatives and clinical trials.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT06114914, 29 October 2023. Retrospectively registered.

Isolation and Identification of the High-Affinity DNA Aptamer Target to the Brain-Derived Neurotrophic Factor (BDNF)

Aptamers are functional oligonucleotide ligands used for the molecular recognition of various targets. The natural characteristics of aptamers make them an excellent alternative to antibodies in diagnostics, therapeutics, and biosensing. DNA aptamers are mainly single-stranded oligonucleotides (ssDNA) that possess a definite binding to targets. However, the application of aptamers to the fields of brain health and neurodegenerative diseases has been limited to date. Herein, a DNA aptamer against the brain-derived neurotrophic factor (BDNF) protein was obtained by in vitro selection. BDNF is a potential biomarker of brain health and neurodegenerative diseases and has functions in the synaptic plasticity and survival of neurons. We identified eight aptamers that have binding affinity for BDNF from a 50-nucleotide library. Among these aptamers, NV_B12 showed the highest sensitivity and selectivity for detecting BDNF. In an aptamer-linked immobilized sorbent assay (ALISA), the NV_B12 aptamer strongly bound to BDNF protein, in a dose-dependent manner. The dissociation constant (Kd) for NV_B12 was 0.5 nM (95% CI: 0.4-0.6 nM). These findings suggest that BDNF-specific aptamers could be used as an alternative to antibodies in diagnostic and detection assays for BDNF.

Does serum neurofilament light help predict accelerated cognitive ageing in unimpaired older adults?

Introduction

Neurofilament light (NfL) is a blood biomarker of neurodegeneration. While serum NfL levels have been demonstrated to increase with normal ageing, the relationship between serum NfL levels and normal age-related changes in cognitive functions is less well understood.

Methods

The current study investigated whether cross-sectional serum NfL levels measured by single molecule array technology (Simoa®) mediated the effect of age on cognition, measured by a battery of neuropsychological tests administered biannually for 8 years, in a cohort of 174 unimpaired older adults (≥50 years) from the Tasmanian Healthy Brain Project. Mediation analysis was conducted using latent variables representing cognitive test performance on three cognitive domains - episodic memory, executive function, and language (vocabulary, comprehension, naming). Cognitive test scores for the three domains were estimated for each participant, coincident with blood collection in 2018 using linear Bayesian hierarchical models.

Results

Higher serum NfL levels were significantly positively associated with age (p < 0.001 for all domains). Cognitive test scores were significantly negatively associated with age across the domains of executive function (p < 0.001), episodic memory (p < 0.001) and language (p < 0.05). However, serum NfL levels did not significantly mediate the relationship between age and cognitive test scores across any of the domains.

Discussion

This study adds to the literature on the relationship between serum NfL levels and cognition in unimpaired older adults and suggests that serum NfL is not a pre-clinical biomarker of ensuing cognitive decline in unimpaired older adults.

Microglia directly associate with pericytes in the central nervous system

Cerebral blood flow (CBF) is important for the maintenance of brain function and its dysregulation has been implicated in Alzheimer's disease (AD). Microglia associations with capillaries suggest they may play a role in the regulation of CBF or the blood-brain-barrier (BBB). We explored the relationship between microglia and pericytes, a vessel-resident cell type that has a major role in the control of CBF and maintenance of the BBB, discovering a spatially distinct subset of microglia that closely associate with pericytes. We termed these pericyte-associated microglia (PEM). PEM are present throughout the brain and spinal cord in NG2DsRed × CX3 CR1+/GFP mice, and in the human frontal cortex. Using in vivo two-photon microscopy, we found microglia residing adjacent to pericytes at all levels of the capillary tree and found they can maintain their position for at least 28 days. PEM can associate with pericytes lacking astroglial endfeet coverage and capillary vessel width is increased beneath pericytes with or without an associated PEM, but capillary width decreases if a pericyte loses a PEM. Deletion of the microglia fractalkine receptor (CX3 CR1) did not disrupt the association between pericytes and PEM. Finally, we found the proportion of microglia that are PEM declines in the superior frontal gyrus in AD. In summary, we identify microglia that specifically associate with pericytes and find these are reduced in number in AD, which may be a novel mechanism contributing to vascular dysfunction in neurodegenerative diseases.

Sex-Specific Protective Effects of Cognitive Reserve on Age-Related Cognitive Decline: A 5-Year Prospective Cohort Study

BACKGROUND AND OBJECTIVES

Females have a higher age-adjusted incidence of Alzheimer disease than males but the reasons for this remain unclear. One proposed contributing factor is that, historically, females had less access to education and, therefore, may accumulate less cognitive reserve. However, educational attainment is confounded by IQ, which in itself is a component of cognitive reserve and does not differ between sexes. Steeper age-related cognitive declines are associated with increased risk of dementia. We, therefore, evaluated the moderating effects of 2 proxies for cognitive reserve, education and IQ, on the steepness of age-related declining cognitive trajectories in unimpaired older males and females.

METHODS

The Tasmanian Healthy Brain Project, a long-term cohort study, recruited healthy Australians aged 50-80 years without cognitive impairment. Baseline cognitive reserve was measured using educational history and IQ, measured by the Wechsler Test of Adult Reading, Full Scale Predicted IQ (WTAR-FSIQ). Cognitive trajectories for language, executive function, and episodic and working memory over 5 years were extracted from neuropsychological assessments. The adjusted effects of education, estimated IQ, and APOE allelic variant on cognitive trajectories were compared between males and females.

RESULTS

Five hundred sixty-two individuals (mean [SD] age 60 [6.7] years; 68% male; 33% APOE ε4+) were followed up over 5 years with 1,924 assessments and 24,946 cognitive test scores (annualized attrition rate 6.6% per year). Estimated IQ correlated with years of education (p < 0.001). Estimated IQ interacted with sex to moderate age-related cognitive trajectories (p = 0.03; adjusted for education); lower IQ males experienced steeper declining trajectories than higher IQ males, but lower IQ females had similar steepness of declining trajectories to higher IQ females. Education was not associated with rate of cognitive decline (p = 0.67; adjusted for WTAR-FSIQ). There were no significant differences in age-related cognitive trajectories between APOE genotypes in either sex.

DISCUSSION

IQ, a measure of cognitive reserve, predicted the steepness of declining cognitive trajectories in males only. Education did not explain as much variation in cognitive trajectories as IQ. Our findings do not support the hypothesis that historical sex disparities in access to education contribute to the higher female incidence of Alzheimer disease.

Preserving choice in breast cancer treatment: A different perspective on contralateral prophylactic mastectomy

Contralateral prophylactic mastectomy is the removal of both breasts when only one is affected by cancer. Rates of this controversial cancer treatment have been increasing since the late 1990s, even among women who do not have the kind of family history or known genetic mutation that would put them at high-risk for another breast cancer. Citing contralateral prophylactic mastectomy's lack of oncologic benefit and increased risk of surgical complications, the American Society of Breast Surgeons discourages contralateral prophylactic mastectomy for average-risk women with unilateral cancer, as does most of the medical literature on this topic. Within this literature, desire for contralateral prophylactic mastectomy is often painted as the product of an emotional overreaction to a cancer diagnosis and misunderstanding of breast cancer risk. Drawing on the personal experience of a breast cancer survivor, as well as relevant medical literature on breast cancer screening and surgery, this article offers a different perspective on the ongoing popularity of contralateral prophylactic mastectomy, one that focuses on practical experiences and logical deliberations about those experiences. Specifically, it calls attention to two features of the contralateral prophylactic mastectomy decision-making situation that have been inadequately covered in the medical literature: (1) the way that breast cancer screening after a breast cancer diagnosis can become a kind of radiological overtreatment, even for "average-risk" women; and (2) how desire for bodily symmetry after breast cancer, which can best be achieved through bilateral reconstruction or no reconstruction, drives interest in contralateral prophylactic mastectomy. The goal of this article is not to suggest that all women who want contralateral prophylactic mastectomy should have the surgery. In some cases, it is not advisable. But many "average-risk" women with unilateral cancer have good reasons for wanting contralateral prophylactic mastectomy, and we believe their right to choose it should be protected.

The TAS Test project: a prospective longitudinal validation of new online motor-cognitive tests to detect preclinical Alzheimer's disease and estimate 5-year risks of cognitive decline and dementia

BACKGROUND

The worldwide prevalence of dementia is rapidly rising. Alzheimer's disease (AD), accounts for 70% of cases and has a 10-20-year preclinical period, when brain pathology covertly progresses before cognitive symptoms appear. The 2020 Lancet Commission estimates that 40% of dementia cases could be prevented by modifying lifestyle/medical risk factors. To optimise dementia prevention effectiveness, there is urgent need to identify individuals with preclinical AD for targeted risk reduction. Current preclinical AD tests are too invasive, specialist or costly for population-level assessments. We have developed a new online test, TAS Test, that assesses a range of motor-cognitive functions and has capacity to be delivered at significant scale. TAS Test combines two innovations: using hand movement analysis to detect preclinical AD, and computer-human interface technologies to enable robust 'self-testing' data collection. The aims are to validate TAS Test to [1] identify preclinical AD, and [2] predict risk of cognitive decline and AD dementia.

METHODS

Aim 1 will be addressed through a cross-sectional study of 500 cognitively healthy older adults, who will complete TAS Test items comprising measures of motor control, processing speed, attention, visuospatial ability, memory and language. TAS Test measures will be compared to a blood-based AD biomarker, phosphorylated tau 181 (p-tau181). Aim 2 will be addressed through a 5-year prospective cohort study of 10,000 older adults. Participants will complete TAS Test annually and subtests of the Cambridge Neuropsychological Test Battery (CANTAB) biennially. 300 participants will undergo in-person clinical assessments. We will use machine learning of motor-cognitive performance on TAS Test to develop an algorithm that classifies preclinical AD risk (p-tau181-defined) and determine the precision to prospectively estimate 5-year risks of cognitive decline and AD.

DISCUSSION

This study will establish the precision of TAS Test to identify preclinical AD and estimate risk of cognitive decline and AD. If accurate, TAS Test will provide a low-cost, accessible enrichment strategy to pre-screen individuals for their likelihood of AD pathology prior to more expensive tests such as blood or imaging biomarkers. This would have wide applications in public health initiatives and clinical trials.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05194787 , 18 January 2022. Retrospectively registered.

Sarm1 knockout modifies biomarkers of neurodegeneration and spinal cord circuitry but not disease progression in the mSOD1G93A mouse model of ALS

The mechanisms underlying the loss of motor neuron axon integrity in amyotrophic lateral sclerosis (ALS) are unclear. SARM1 has been identified as a genetic risk variant in sporadic ALS, and the SARM1 protein is a key mediator of axon degeneration. To investigate the role of SARM1 in ALS-associated axon degeneration, we knocked out Sarm1 (Sarm1^KO) in mSOD1^G93ATg (mSOD1) mice. Animals were monitored for ALS disease onset and severity, with motor function assessed at pre-symptomatic and late-stage disease and lumbar spinal cord and sciatic nerve harvested for immunohistochemistry at endpoint (20 weeks). Serum was collected monthly to assess protein concentrations of biomarkers linked to axon degeneration (neurofilament light (NFL) and tau), and astrogliosis (glial fibrillary acidic protein (GFAP)), using single molecule array (Simoa®) technology. Overall, loss of Sarm1 in mSOD1 mice did not slow or delay symptom onset, failed to improve functional declines, and failed to protect motor neurons. Serum NFL levels in mSOD1 mice increased between 8 -12 and 16-20 weeks of age, with the later increase significantly reduced by loss of SARM1. Similarly, loss of SARM1 significantly reduced an increase in serum GFAP between 16 and 20 weeks of age in mSOD1 mice, indicating protection of both global axon degeneration and astrogliosis. In the spinal cord, Sarm1 deletion protected against loss of excitatory VGluT2-positive puncta and attenuated astrogliosis in mSOD1 mice. In the sciatic nerve, absence of SARM1 in mSOD1 mice restored the average area of phosphorylated neurofilament reactivity towards WT levels. Together these data suggest that Sarm1^KO in mSOD1 mice is not sufficient to ameliorate functional decline or motor neuron loss but does alter serum biomarker levels and provide protection to axons and glutamatergic synapses. This indicates that treatments targeting SARM1 could warrant further investigation in ALS, potentially as part of a combination therapy.

Association Between Components of Cognitive Reserve and Serum BDNF in Healthy Older Adults

Background: The brain-derived neurotrophic factor (BDNF) protein has been shown to have a prominent role in neuron survival, growth, and function in experimental models, and the BDNF Val66Met polymorphism which regulates its expression has been linked to resilience toward the effects of aging on cognition. Cognitively stimulating activity is linked to both increased levels of BDNF in the brain, and protection against age-related cognitive decline. The aim of this study was to investigate the associations between serum BDNF levels, the BDNF Val66Met genotype, and components of cognitive reserve in early and mid-life, measured with the Lifetime of Experiences Questionnaire (LEQ). Methods: Serum BDNF levels were measured cross-sectionally in 156 participants from the Tasmanian Healthy Brain Project (THBP) cohort, a study examining the potential benefits of older adults engaging in a university-level education intervention. Multiple linear regression was used to estimate serum BDNF's association with age, education, gender, BDNF Val66Met genotype, later-life university-level study, and cognitively stimulating activities measured by the LEQ. Results: Serum BDNF in older adults was associated with early life education and training, increasing 0.007 log(pg/ml) [95%CI 0.001, 0.012] per unit on the LEQ subscale. Conversely, education and training in mid-life were associated with a -0.007 log(pg/ml) [-0.012, -0.001] decrease per unit on the LEQ subscale. Serum BDNF decreased with age (-0.008 log(pg/ml) [-0.015, -0.001] per year), and male gender (-0.109 log(pg/ml) [-0.203, -0.015]), but mean differences between the BDNF Val66Met polymorphisms were not significant (p = 0.066). All effect sizes were small, with mid-life education and training having the largest effect size ( η p 2 = 0.044). Conclusion: Education in both early and mid-life explained small but significant amounts of variance in serum BDNF levels, more than age or gender. These effects were opposed and independent, suggesting that education at different stages of life may be associated with different cognitive and neural demands. Education at different stages of life may be important covariates when estimating associations between other exposures and serum BDNF.

Clinical outcomes among patients with tuberculous meningitis receiving intensified treatment regimens

SETTING: National Center for Tuberculosis and Lung Diseases (NCTLD), Tbilisi, Georgia.OBJECTIVE: To determine clinical outcomes of patients with tuberculous meningitis (TBM) treated with an intensified regimen including a fluoroquinolone (FQ) and an injectable agent.DESIGN: Prospective cohort of patients aged ≥16 years initiating treatment for TBM at the NCTLD from January 2018 to December 2019. Treatment outcomes and neurologic disability at 1, 6 and 12 months after treatment initiation were assessed.RESULTS: Among 77 patients with median follow-up time of 363 days (IQR 269-374), 97% received a FQ, 62% an injectable agent, 44% linezolid and 39% a carbapenem. Fifty-seven patients (74%) successfully completed treatment, 2 (2.6%) had treatment failure, 6 (7.8%) died, and the remainder (12%) were lost to follow up. Among 11 patients treated for multidrug-resistant TBM, the median follow-up time was 467 days and one patient (8%) died. Regarding neurologic outcomes, 14/76 (18%) patients had Modified Rankin Scores of 0 at baseline, improving to 85% (56/66) and 94% (47/50) at 6 and 12 months, respectively.CONCLUSION: Intensified multidrug treatment regimens including a FQ and an injectable agent in all patients and newly implemented drugs in patients with multidrug-resistant TBM resulted in low mortality and favorable neurologic outcomes.

Coherence and cognition in the cortex: the fundamental role of parvalbumin, myelin, and the perineuronal net

The calcium binding protein parvalbumin is expressed in interneurons of two main morphologies, the basket and chandelier cells, which target perisomatic domains on principal cells and are extensively interconnected in laminar networks by synapses and gap junctions. Beyond its utility as a convenient cellular marker, parvalbumin is an unambiguous identifier of the key role that these interneurons play in the fundamental functions of the cortex. They provide a temporal framework for principal cell activity by propagating gamma oscillation, providing coherence for cortical information processing and the basis for timing-dependent plasticity processes. As these parvalbumin networks mature, they are physically and functionally stabilised by axonal myelination and development of the extracellular matrix structure termed the perineuronal net. This maturation correlates with the emergence of high-speed, highly energetic activity and provides a coherent foundation for the unique ability of the cortex to cross-correlate activity across sensory modes and internal representations.

Pathological Links between Traumatic Brain Injury and Dementia: Australian Pre-Clinical Research

Traumatic brain injury (TBI) can cause persistent cognitive changes and ongoing neurodegeneration in the brain. Accumulating epidemiological and pathological evidence implicates TBI in the development of Alzheimer's disease, the most common cause of dementia. Further, the TBI-induced form of dementia, called chronic traumatic encephalopathy, shares many pathological hallmarks present in multiple different diseases which cause dementia. The inflammatory and neuritic responses to TBI and dementia overlap, indicating that they may share common pathological mechanisms and that TBI may ultimately cause a pathological cascade culminating in the development of dementia. This review explores Australian pre-clinical research investigating the pathological links between TBI and dementia.

Prevalence of pulmonary tuberculosis among students in three eastern Ethiopian universities

SETTINGS

Three universities located in eastern Ethiopia: Haramaya University, Haramaya; Dire-Dawa University, Dire-Dawa; and Jigjiga University, Jigjiga.

OBJECTIVE

To determine the burden of pulmonary tuberculosis (PTB) among university students and to identify risk factors for the development of TB disease.

DESIGN

All full-time university students were screened for symptoms of PTB and sputum was collected for acid-fast bacilli (AFB) examination and culture for Mycobacterium tuberculosis.

RESULTS

Of 35 344 students screened, we identified 153 PTB cases that occurred over the 1-year study period, or 433/100 000 students. Of these, 117 (76%) PTB cases were found through passive case finding at student health centres, while 36 (24%) previously undiagnosed patients were identified through active case finding. Sixteen cases detected using active case finding (44%) were smear-positive. Living in a dormitory with 5 students and attending university for 2 years were both significantly associated with PTB (adjusted OR 2.49 and 3.79, respectively, P < 0.001). In persons who underwent drug susceptibility testing, 11 (30.5%) had resistance to at least one first-line anti-tuberculosis drug.

CONCLUSION

We found a high burden of TB among university students in eastern Ethiopia. Screening for PTB upon university admission and at regular intervals should be considered to minimise TB transmission on university campuses.

Late-life environmental enrichment preserves short-term memory and may attenuate microglia in male APP/PS1 mice

Environmental enrichment (EE) has been consistently reported to enhance cognitive function in mouse models of neuropathology. Microglia, implicated in Alzheimer's disease pathology, may mediate this effect. The aim of the present study was to investigate the effect of EE on cognitive function and microglia in mouse models of aging and amyloidosis. Male wild-type (Wt) and APP/PS1 mice were randomly assigned to standard housing (SH) or EE from 12 to 18 months of age. Spatial memory testing was performed using the Y and Barnes maze. Immunohistochemical analysis of Aβ load, Iba1 and CD-68-labeled (phagocytic-type) microglia was examined between conditions. EE from 12 months of age was associated with improved short-term memory performance in APP/PS1 mice, despite no reductions to Aβ load. APP/PS1 mice in SH had significantly increased microglia occupying the neocortex and hippocampus (p = 0.02; p = 0.004, respectively) relative to Wt animals. Microglia labeling was not statistically different between EE-exposed APP/PS1 compared to Wt mice, indicating that EE may attenuate the increased microglial load in aging APP/PS1 mice. APP/PS1 mice from EE had significantly (p = 0.01) higher colocalization of Iba1 and CD-68 labeling, indicative of increased phagocytic microglia compared to mice from SH. The findings of the present study suggest that EE after substantial brain amyloidosis, has the potential to preserve domains of cognitive function, while having no effect on Aβ deposition. The current study demonstrates that EE may attenuate microglia in aging APP/PS1 mice, and may promote alterations in cellular phenotype.

Age Moderates the Effects of Traumatic Brain Injury on Beta-Amyloid Plaque Load in APP/PS1 Mice

Traumatic brain injury (TBI) has been identified as a risk factor for Alzheimer's disease (AD). However, how such neural damage contributes to AD pathology remains unclear; specifically, the relationship between the timing of a TBI relative to aging and the onset of AD pathology is not known. In this study, we have examined the effect of TBI on subsequent beta-amyloid (Aβ) deposition in APP/PS1 (APP_SWE/PSEN1dE9) transgenic mice either before (3 months of age) or after the onset (6 months of age) of plaque pathology. Lateral fluid percussion injury (LFPI), a model of diffuse brain injury, was induced in APP/PS1 and C57Bl/6 wild-type (WT) littermates. LFPI caused a significant increase in both total (p < 0.001) and fibrillar (p < 0.001) Aβ plaque load in the cortex of 3-month-old APP/PS1 mice compared to sham-treated mice at 30 days post-injury. However, in the cortex of 6-month-old mice at 30 days post-injury, LFPI caused a significant decrease in total (p < 0.01), but not fibrillar (p > 0.05), Aβ plaque load compared to sham-treated mice. No Aβ plaques were present in any WT mice across these conditions. Glial fibrillary acidic protein immunolabeling of astrocytes and ionized calcium-binding adapter molecule 1 immunolabeling of microglial/macrophages was not significantly different (p < 0.05) in injured animals compared to sham mice, or APP/PS1 mice compared to WT mice. The current data indicate that TBI may have differential effects on Aβ plaque deposition depending on the age and the stage of amyloidosis at the time of injury.

Highly Variable Expression of ESR1 Splice Variants in Human Liver: Implication in the Liver Gene Expression Regulation and Inter-Person Variability in Drug Metabolism and Liver Related Diseases

Estrogen receptor alpha (ESR1) plays an important role in many tissues including the liver. Numerous alternative splice variants of ESR1 exist that encode ESR1 proteins with varying functions. We aim to study ESR1 genomic organization and its mRNA expression profile in human liver by incorporating information from literature and genomic databases (Ensembl, NCBI and GTEx), and employing a quantitative method to measure all known ESR1 mRNA splice variants in 36 human livers. We re-constructed ESR1 genomic organization map that contains 29 exons. ESR1 mRNA splice variants with varying 5' untranslated region (5'UTR) and/or missing each of eight coding exons are readily detectable in liver and other tissues. Moreover, we found extensive inter-individual variability in splice variant pattern of ESR1 transcripts. Specifically, ESR1 transcripts lacking first coding exon are the main transcripts in liver, which encode ESR1 proteins missing N-terminal 173 amino acids (for example, ERα46), reported previously to have either constitutive activity or dominant negative effects depending on cellular context. Moreover, some livers predominantly express ESR1 transcripts missing exon 10 or 16, encoding C-terminal truncated ESR1 proteins with varying ESR1 activities. Inter-person variability in ESR1 expression profile may contribute to inter-person variability in drug metabolism and susceptibility to liver related diseases.

Accurate and Unbiased Quantitation of Amyloid-β Fluorescence Images Using ImageSURF

BACKGROUND

Images of amyloid-β pathology characteristic of Alzheimer's disease are difficult to consistently and accurately segment, due to diffuse deposit boundaries and imaging variations.

METHODS

We evaluated the performance of ImageSURF, our open-source ImageJ plugin, which considers a range of image derivatives to train image classifiers. We compared ImageSURF to standard image thresholding to assess its reproducibility, accuracy and generalizability when used on fluorescence images of amyloid pathology.

RESULTS

ImageSURF segments amyloid-β images significantly more faithfully, and with significantly greater generalizability, than optimized thresholding.

CONCLUSION

In addition to its superior performance in capturing human evaluations of pathology images, ImageSURF is able to segment image sets of any size in a consistent and unbiased manner, without requiring additional blinding, and can be retrospectively applied to existing images. The training process yields a classifier file which can be shared as supplemental data, allowing fully open methods and data, and enabling more direct comparisons between different studies.

Protein coding mitochondrial-targeted RNAs rescue mitochondrial disease in vivo

Mitochondrial encephalomyopathies (MEs) result from mutations in mitochondrial genes critical to oxidative phosphorylation. Severe and untreatable ME results from mutations affecting each endogenous mitochondrial encoded gene, including all 13 established protein coding genes. Effective techniques to manipulate mitochondrial genome are limited and targeted mitochondrial protein expression is currently unavailable. Here we report the development of a mitochondrial-targeted RNA expression (mtTRES) vector capable of protein expression within mitochondria (mtTRES^Pro). We demonstrate that mtTRES^Pro expressed RNAs are targeted to mitochondria and are capable of being translated using EGFP encoded constructs in vivo. We additionally test mtTRES^Pro constructs encoding wild type ATP6 for their ability to rescue an established ATP6¹Drosophila model of ME. Genetic rescue is examined including tests with co-expression of mitochondrial targeted translational inhibitors TLI-NCL::ATP6 RNAs that function to reduce expression of the endogenous mutant protein. The data demonstrate allotopic RNA expression of mitochondrial targeted wild type ATP6 coding RNAs are sufficient to partially rescue a severe and established animal model of ME but only when combined with a method to inhibit mutant protein expression, which likely competes for incorporation into complex V.

Utility of 18F-fluoroestradiol (18F-FES) PET/CT imaging as a pharmacodynamic marker in patients with refractory estrogen receptor-positive solid tumors receiving Z-endoxifen therapy

BACKGROUND

Z-endoxifen is the most potent of the metabolites of tamoxifen, and has the potential to be more effective than tamoxifen because it bypasses potential drug resistance mechanisms attributable to patient variability in the expression of the hepatic microsomal enzyme CYP2D6. ¹⁸F-FES is a positron emission tomography (PET) imaging agent which selectively binds to estrogen receptor alpha (ER-α) and has been used for non-invasive in vivo assessment of ER activity in tumors. This study utilizes ¹⁸F-FES PET imaging as a pharmacodynamic biomarker in patients with ER+ tumors treated with Z-endoxifen.

METHODS

Fifteen patients were recruited from a parent therapeutic trial of Z-endoxifen and underwent imaging with ¹⁸F-FES PET at baseline. Eight had positive lesions on the baseline scan and underwent follow-up imaging with ¹⁸F-FES 1-5 days post administration of Z-endoxifen.

RESULTS

Statistically significant changes (p = 0.0078) in standard uptake value (SUV)-Max were observed between the baseline and follow-up scans as early as 1 day post drug administration.

CONCLUSION

F-FES PET imaging could serve as a pharmacodynamic biomarker for patients treated with ER-directed therapy.

The axon as a physical structure in health and acute trauma

The physical structure of neurons - dendrites converging on the soma, with an axon conveying activity to distant locations - is uniquely tied to their function. To perform their role, axons need to maintain structural precision in the soft, gelatinous environment of the central nervous system and the dynamic, flexible paths of nerves in the periphery. This requires close mechanical coupling between axons and the surrounding tissue, as well as an elastic, robust axoplasm resistant to pinching and flattening, and capable of sustaining transport despite physical distortion. These mechanical properties arise primarily from the properties of the internal cytoskeleton, coupled to the axonal membrane and the extracellular matrix. In particular, the two large constituents of the internal cytoskeleton, microtubules and neurofilaments, are braced against each other and flexibly interlinked by specialised proteins. Recent evidence suggests that the primary function of neurofilament sidearms is to structure the axoplasm into a linearly organised, elastic gel. This provides support and structure to the contents of axons in peripheral nerves subject to bending, protecting the relatively brittle microtubule bundles and maintaining them as transport conduits. Furthermore, a substantial proportion of axons are myelinated, and this thick jacket of membrane wrappings alters the form, function and internal composition of the axons to which it is applied. Together these structures determine the physical properties and integrity of neural tissue, both under conditions of normal movement, and in response to physical trauma. The effects of traumatic injury are directly dependent on the physical properties of neural tissue, especially axons, and because of axons' extreme structural specialisation, post-traumatic effects are usually characterised by particular modes of axonal damage. The physical realities of axons in neural tissue are integral to both normal function and their response to injury, and require specific consideration in evaluating research models of neurotrauma.

Abstract PD2-03: Final results of a first-in-human phase I study of the tamoxifen (TAM) metabolite, Z-Endoxifen hydrochloride (Z-Endx) in women with aromatase inhibitor (AI) refractory metastatic breast cancer (MBC) (NCT01327781)

Background: AI's are more effective than TAM in ER+ breast cancer. In AI refractory MBC, the response rate to TAM is 0% (Osborne 2011). Z-Endx is an active metabolite of TAM and among TAM treated women in the adjuvant and metastatic settings, reduced CYP2D6 metabolism and low Endx concentrations (Css &lt;20 nM) have been associated with increased likelihood of disease recurrence. Preclinical studies have demonstrated greater Z-Endx exposure and anti-tumor activity with oral Z-Endx compared to equivalent doses of oral TAM (Reid 2014)

Methods: We conducted a phase I trial to determine the maximum-tolerated dose (MTD) and evaluate the toxicities, clinical activity, and pharmacokinetics (PK) of Z-Endx in patients (pts) with ER+, AI refractory MBC. Unlimited prior endocrine regimens were allowed. An accelerated titration schedule was applied (2 pts/dose level) until moderate toxicity or DLT, followed by a 3+3 design and then to expansion cohorts (40, 80, and 100 mg/day). Z-Endx was administered orally once daily (28 day cycle). Eye exams were performed at baseline, and end of cycles 2 and 6. PK was performed during cycle 1 and prior to subsequent cycles. For pts in the expansion cohorts, tumor biopsies were obtained at baseline for DNA sequencing (Foundation Medicine). Plasma cholesterol levels were obtained at baseline and after 1 cycle.

Results: From March 2011 to Dec 2014, 41 pts (38 evaluable), median age 60, received Z-Endx once daily encompassing 7 dose levels (20-160 mg/daily). The median number of prior hormonal regimens was 2 and 3 for the dose escalation and expansion cohorts, respectively. Dose escalation was stopped at 160 mg/day given MTD not reached and attainment of mean Endx Css of 3.6 uM. Cycle 1 DLT (PE) was observed in one patient (60 mg). No eye toxicity was observed. PK demonstrated mean Endx Css of &gt; 1 uM at all dose levels ≥ 40 mg/day. Antitumor activity was observed at multiple dose levels including 3 confirmed partial responses and an additional 7 with stable disease for ≥6 cycles. Of these 10 pts, 9 had prior progression on both AI and fulvestrant and 3 additionally on TAM. After 1 cycle, total and LDL cholesterol decreased &gt; 20 points in 54% and 40% of pts, respectively. Tumor sequencing in the expansion cohorts (n=14) did not identify ESR1 mutations; however, ESR1 amplification was identified in 1 pt with prolonged stable disease (&gt;200 days). Of 6 pts with rapid progression (≤2 cycles), 4/6 had either CCND1 amplification (n=1) or at least one of the following activating mutations: ERBB2 L755S (n=1), AKT1 E17K (n=1), MTOR E1799K (n=1).

Conclusions: The direct administration of Z-END provides substantial drug exposure, acceptable toxicity, and "proof of principle" antitumor activity in endocrine resistant MBC. While the MTD was not determined, the goal of achieving Endx Css concentrations of &gt; 1 uM was achieved. Tumor sequencing identified pts with predicted and confirmed endocrine resistance. A randomized phase II comparing endoxifen (80 mg/day) with TAM in AI refractory MBC was recently activated (NCT02311933). Supported in part by CA 133049, CA186686, CA15083, CA116201, and CA15083.

Citation Format: Goetz MP, Suman VJ, Reid JM, Northfelt DW, Mahr MA, Dockter T, Kuffel M, Buhrow SA, Safgren SL, McGovern RM, Collins JM, Streicher H, Hawse JR, Haddad TC, Erlichman C, Ames MM, Ingle JN. Final results of a first-in-human phase I study of the tamoxifen (TAM) metabolite, Z-Endoxifen hydrochloride (Z-Endx) in women with aromatase inhibitor (AI) refractory metastatic breast cancer (MBC) (NCT01327781). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD2-03.

The effect of focal brain injury on beta-amyloid plaque deposition, inflammation and synapses in the APP/PS1 mouse model of Alzheimer's disease

Traumatic brain injury is a risk factor for Alzheimer's disease (AD), however the effect of such neural damage on the onset and progression of beta-amyloid (Aβ) plaque pathology is not well understood. This study utilized an in vivo model of focal brain injury to examine how localized damage may acutely affect the onset and progression of Aβ plaque deposition as well as inflammatory and synaptic changes, in the APP/PS1 (APPSWE, PSEN1dE9) transgenic model of AD relative to wild-type (Wt) mice. Acute focal brain injury in 3- and 9-month-old APP/PS1 and Wt mice was induced by insertion of a needle into the somatosensory neocortex, as compared to sham surgery, and examined at 24h and 7d post-injury (PI). Focal brain injury did not induce thioflavine-S stained or (pan-Aβ antibody) MOAB-2-labeled plaques at either 24h or 7d PI in 3-month-old APP/PS1 mice or Wt mice. Nine-month-old APP/PS1 mice demonstrate cortical Aβ plaques but focal injury had no statistically significant (p>0.05) effect on thioflavine-S or MOAB-2 plaque load surrounding the injury site at 24h PI or 7d PI. There was a significant (p<0.001) increase in cross-sectional cortical area occupied by Iba-1 positive microglia in injured mice compared to sham animals, however this response did not differ between APP/PS1 and Wt mice (p>0.05). For both Wt and APP/PS1 mice alike, synaptophysin puncta near the injury site were significantly reduced 24h PI (compared to sites distant to the injury and the corresponding area in sham mice; p<0.01), but not after 7d PI (p>0.05). There was no significant effect of genotype on this response (p>0.05). These results indicate that focal brain injury and the associated microglial response do not acutely alter Aβ plaque deposition in the APP/PS1 mouse model. Furthermore the current study demonstrated that the brains of both Wt and APP/PS1 mice are capable of recovering lost synaptophysin immunoreactivity post-injury, the latter in the presence of Aβ plaque pathology that causes synaptic degeneration.

Functional diversity of five homologous Cu+-ATPases present in Sinorhizobium meliloti

Copper is an important element in host-microbe interactions, acting both as a catalyst in enzymes and as a potential toxin. Cu(+)-ATPases drive cytoplasmic Cu(+) efflux and protect bacteria against metal overload. Many pathogenic and symbiotic bacteria contain multiple Cu(+)-ATPase genes within particular genetic environments, suggesting alternative roles for each resulting protein. This hypothesis was tested by characterizing five homologous Cu(+)-ATPases present in the symbiotic organism Sinorhizobium meliloti. Mutation of each gene led to different phenotypes and abnormal nodule development in the alfalfa host. Distinct responses were detected in free-living S. meliloti mutant strains exposed to metal and redox stresses. Differential gene expression was detected under Cu(+), oxygen or nitrosative stress. These observations suggest that CopA1a maintains the cytoplasmic Cu(+) quota and its expression is controlled by Cu(+) levels. CopA1b is also regulated by Cu(+) concentrations and is required during symbiosis for bacteroid maturation. CopA2-like proteins, FixI1 and FixI2, are necessary for the assembly of two different cytochrome c oxidases at different stages of bacterial life. CopA3 is a phylogenetically distinct Cu(+)-ATPase that does not contribute to Cu(+) tolerance. It is regulated by redox stress and required during symbiosis. We postulated a model where non-redundant homologous Cu(+)-ATPases, operating under distinct regulation, transport Cu(+) to different target proteins.

Contribution of indirect computed tomography venography to computed tomography angiography of the chest for the diagnosis of thromboembolic disease in two United States emergency departments

Recent reports suggest that physicians in non-ambulatory settings can use indirect CT venography (CTV) of the lower extremities immediately following spiral CT angiography (CTA) of the chest to identify patients with a negative CTA who have thromboembolic disease identified on CTV. We sought to determine the frequency of isolated deep venous thrombosis (DVT) discovered on CTV in emergency department (ED) patients with complaints suggestive of pulmonary embolism (PE) yet having a negative CTA. This study was conducted in a suburban and urban ED where patients with symptoms suspicious for PE were primarily evaluated with CTA and CTV. A total of 800 patients were studied, including 360 from the suburban ED and 440 from the urban ED. 88 (11%) patients were diagnosed with thromboembolic disease by CTA, or CTV, or both. Seventy-three patients had a CTA of the chest that was positive for PE, 42 (5.2%) of whom had evidence of both PE on CTA and DVT on CTV. Fifteen patients (2%, 95% CI = 1-3%) had a negative CTA and were subsequently found to have isolated DVT on CTV, all of whom received anticoagulation therapy. These data suggest that indirect CT venography of immediately following CT angiography of the chest significantly increased the frequency of diagnosed thromboembolic disease requiring anticoagulation in ED patients with suspected PE.

Thymidine phosphorylase as a target for imaging and therapy with thymine analogs

PURPOSE

Thymidine phosphorylase (TPase; platelet-derived endothelial cell growth factor) is an attractive target for imaging and therapy because of the strong relationship between its expression in tumor biopsies and clinical outcome in many tumor types. Although the mechanism has yet to be explained, expression of TPase is highly associated with angiogenesis.

METHODS

Tumor cells were phenotyped for TPase activity, and incubated with thymine or its analogs (5-X-Ura). After intracellular conversion to thymidine analogs via the reverse reaction for TPase, these molecules were phosphorylated and incorporated into DNA.

RESULTS

Preferential localization was found in cells with high TPase, e.g. U937. Incorporation was enhanced in cells with high TPase by coincubation with modulators such as deoxyuridine.

CONCLUSIONS

5-X-Ura molecules can be readily labeled with positron emitters, and this finding provides support for further evaluation in vivo of their potential as probes for noninvasive external imaging of TPase, both at the time of diagnosis and during maneuvers intended to manipulate TPase. If the 5-X-Ura molecules were labeled with a therapeutic isotope, e.g. 125I or 211At, selective cytotoxicity would be expected in cells with high TPase expression. However, direct evaluation of the safety in vivo of the therapeutic approach is required. The 5-X-Ura compounds constitute a novel approach to both imaging and therapy directed towards TPase. Further, there are distinct advantages to using the imaging mode to identify tumors likely to benefit from therapy with the same set of molecules.

Metabolism of vanoxerine, 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine, by human cytochrome P450 enzymes

Vanoxerine (1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine; GBR12909) is a promising agent for the treatment of cocaine dependence. Knowledge of the major pathway for GBR12909 metabolism is important for prediction of the likelihood of drug-drug interactions, which may affect the therapeutic clinical outcome, when this agent is used in cocaine-dependent individuals receiving multiple drug therapy. We studied biotransformation of GBR12909 in human liver microsomes (n = 4), human hepatocytes, and microsomes containing cDNA-expressed human P450 isoforms with GBR12909 concentrations within the range of steady-state plasma concentrations detected in healthy volunteers. A high-pressure liquid chromatography assay was used to measure parent GBR12909 and its primary metabolite. GBR12909 was metabolized by human liver microsomes, hepatocytes, and cDNA-expressed human P450s to a single metabolite. Ketoconazole, a selective inhibitor of CYP3A, reduced GBR12909 biotransformation in human liver microsomes and primary hepatocytes by 92 +/- 2 and 92.4 +/- 0.4%, respectively. Quercetin (an inhibitor of CYP2C8/3A4) was a less effective inhibitor producing 62 +/- 22% inhibition in human liver microsomes and 54 +/- 35% in hepatocytes. Other P450 selective inhibitors did not decrease GBR12909 biotransformation more than 29% in either human liver microsomes or hepatocytes with the exception of chlorzoxazone (CYP2E1), which inhibited GBR12909 biotransformation by 71.4 +/- 18.5% in primary human hepatocytes. Ciprofloxacin (CYP1A2), sulfaphenazole (CYP2C9), quinidine (CYP2D6), chlorzoxazone (CYP2E1), and mephenytoin (CYP2C19) did not demonstrate statistically significant inhibition (p > 0.05) of GBR12909 biotransformation in liver microsomes. cDNA-expressed P450 3A4 metabolized GBR12909 to a greater extent than 2C8 and 2E1. These data suggest the possibility that multiple P450 isoforms may be involved in human GBR12909 metabolism but that CYP3A appears to be the major enzyme responsible for human GBR12909 biotransformation.

Inter-species differences in drug properties

There has been a clear trend towards decreased reliance upon animal studies and increased emphasis upon experiments with human-derived tissues. Nonetheless, we continue to need investigations of interspecies differences for two principal reasons: (1) to prospectively design experiments so that the animal species most similar to humans can be chosen, on a case-by-case basis, for each drug; (2) to properly evaluate and interpret data obtained from the experiments ("risk assessment"). Four core examples derived from the work in our FDA laboratory are used to illustrate these points. For paclitaxel, different metabolites were formed in humans and rats, which makes metabolic drug-drug interaction studies in rats irrelevant. For zidovudine (AZT), rapid glucuronidation in humans produced a much shorter half-life than expected from studies in animals, which have negligible glucuronidation. The toxicology and efficacy of both parent drug and metabolite need to be assessed in cases such as iododeoxydoxorubicin, in which the parent molecule is the dominant circulating species in mice, but patients have more than 10-fold greater exposure to the metabolite compared with the parent. While rats have highly-active arylamine N-acetyltransferases, dogs totally lack this enzyme family, and humans have intermediate amounts. For some situations, we've suggested that it can be desirable to inhibit NAT to make the human exposure more similar to dogs. In conclusion, although the ratio of animal:human data is decreasing, our ability to use animal data effectively for drug development has actually increased. Continued focus should be placed upon the application of comparative interspecies data for prospective design of animal experiments and retrospective interpretation of animal findings in terms of the potential for human risk and benefit.

In vitro human tissue models in risk assessment: report of a consensus-building workshop

Advances in the technology of human cell and tissue culture and the increasing availability of human tissue for laboratory studies have led to the increased use of in vitro human tissue models in toxicology and pharmacodynamics studies and in quantitative modeling of metabolism, pharmacokinetic behavior, and transport. In recognition of the potential importance of such models in toxicological risk assessment, the Society of Toxicology sponsored a workshop to evaluate the current status of human cell and tissue models and to develop consensus recommendations on the use of such models to improve the scientific basis of risk assessment. This report summarizes the evaluation by invited experts and workshop attendees of the current status of such models for prediction of human metabolism and identification of drug-drug interactions, prediction of human toxicities, and quantitative modeling of pharmacokinetic and pharmaco-toxicodynamic behavior. Consensus recommendations for the application and improvement of current models are presented.

Effects of cytochrome P450 inducers on 17alpha-ethinyloestradiol (EE2) conjugation by primary human hepatocytes

AIMS

Our objective was to elucidate further the underlying mechanism responsible for therapeutic failures observed with concomitant administration of the oral contraceptive 17alpha-ethinyloestradiol (EE2 ) and rifampicin.

METHODS

We investigated both oxidative and direct conjugative [3H]-EE2 metabolism by human liver S9 fraction and the effect of known enzyme-inducing drugs using a human hepatocyte induction model in vitro.

RESULTS

Cofactor dependent [3H]-EE2 metabolism by human liver S9 fraction produced 2-hydroxy-[3H]-EE2, 2-methoxy-[3H]-EE2, and direct [3H]-EE2 sulphate and glucuronide conjugates. Only two detectable metabolites of [3H]-EE2 were produced by the S9 fraction in the presence of all cofactors: [3H]-EE2-3-sulphate (75.7+/-7.6% s. d.) and 2-methoxy-3H-EE2 (2.6%+/-0.5% s.d.). Human hepatocytes extensively metabolized [3H]-EE2 to its glucuronide and sulphate conjugates. Small amounts of a 2-methoxy-[3H]-EE2 3-conjugate, < or = 10%, was observed but no. 2-hydroxy-[3H]-EE2 was detected. An unexpected finding in our study was increased [3H]-EE2-3-sulphate production (1.5-3.3 fold, n=3 donor livers) by hepatocytes pretreated with rifampicin compared to control hepatocytes. No statistically significant increase in [3H]-EE2-3-sulphation was observed in hepatocytes pretreated with 3-methylcholanthrene, phenobarbitone, dexamethasone, or omeprazole over nontreated hepatocytes. To our knowledge, this is the first observation of sulphotransferase induction by rifampicin in human hepatocytes in vitro resulting in increased [3H]-EE2 sulphation.

CONCLUSIONS

Our data indicate that the major EE2 metabolic products formed by human hepatocytes in vitro are direct EE2 conjugates with EE2 oxidation representing minor pathways. Further studies are required to establish the mechanism of sulphotransferase induction and the clinical relevance of our findings.

Quality-of-service improvements from coupling a digital chest unit with integrated speech recognition, information, and picture archiving and communications systems

Speech recognition reporting for chest examinations was introduced and tightly integrated with a Radiology Information System (RIS) and a Picture Archiving and Communications System (PACS). A feature of this integration was the unique one-to-one coupling of the workstation displayed case and the reporting via speech recognition for that and only that particular examination and patient. The utility of the resulting, wholly integrated electronic environment was then compared with that of the previous analog chest unit and dedicated wet processor, with reporting of hard copy examinations by direct dictation to a typist. Improvements in quality of service in comparison to the previous work environment include (1) immediate release of the patient, (2) decreased rate of repeat radiographs, (3) improved image quality, (4) decreased time for the examination to be available for interpretation, (5) automatic hanging of current and previous images, (6) ad-hoc availability of images, (7) capability of the radiologist to immediately review and correct the transcribed report, (8) decreased time for clinicians to view results, and (9) increased capacity of examinations per room.

Suicide prodrugs activated by thymidylate synthase: rationale for treatment and noninvasive imaging of tumors with deoxyuridine analogues

Most tumors are resistant to therapy by thymidylate synthase (TS) inhibitors due to their high levels of TS. Instead of inhibiting TS, we hypothesized that it was possible to use this enzyme to activate suicide prodrugs (deoxyuridine analogues) to more toxic species (thymidine analogues). Tumors with high levels of TS could be particularly sensitive to deoxyuridine analogues because they would be more efficient in producing the toxic methylated species. Furthermore, the accumulation of methylated species within tumors could be visualized externally if a tracer dose of the deoxyuridine analogue was tagged with an isotope, preferably a positron emitter, such as 18F. Higher accumulation of isotope indicates higher activity of TS and lower sensitivity of the tumor to TS inhibitors, but perhaps more sensitivity to therapy with deoxyuridine analogues as suicide prodrugs. 2'-F-ara-deoxyuridine (FAU) was used as a prototype to demonstrate these concepts experimentally. FAU readily entered cells and was phosphorylated, methylated, and subsequently incorporated into cellular DNA. Among different cell lines, FAU produced varying degrees of growth inhibition. Greater DNA incorporation (e.g., for CEM and U-937 cells) was reflected as increased toxicity. FAU produced less DNA incorporation in Raji or L1210 cells, and growth rate was minimally decreased. As the first demonstration that cells with high levels of TS activity can be more vulnerable to therapy than cells with low TS activity, this preliminary work suggests a new therapeutic approach for common human tumors that were previously resistant. Furthermore, it appears that the TS activity of tumors could be noninvasively imaged in situ by tracer doses of [18F]FAU and that this phenotypic information could guide patient therapy.

Testing the Equivalence of the Socialization Factor Structure for Criminals and Noncriminals

Considerable evidence supports the criterion-related validity of the Socialization (So) scale of the California Psychological Inventory (Gough, 1948, 1994, 1996) for the prediction of antisocial and prosocial behavior. However, no research has examined the similarity of the So construct for the two populations. Meaningful interpretation of So scores is possible if the factor structure is equivalent for antisocial and prosocial groups.

Salvage brachytherapy for localized prostate cancer after radiotherapy failure

OBJECTIVES

To evaluate the effectiveness and morbidity of salvage brachytherapy for locally recurrent or persistent prostate cancer after radiotherapy failure.

METHODS

In this retrospective study, 49 patients of median age 73.3 years (range 52.9 to 86.9) with biopsy-proven localized prostate cancer underwent interactive transperineal fluoroscopic-guided and biplane ultrasound-guided brachytherapy with either iodine 125 or palladium 103 after prior radiotherapy failure. Post-treatment follow-up was conducted for a median of 64.1 months (range 26.6 to 96.8) and included clinical assessment of disease status, assays of serum prostate-specific antigen (PSA) levels, and documentation of treatment-related symptoms and complications. Determination of biochemical treatment failure was based on two successive rising PSA values above the post-treatment PSA nadir value.

RESULTS

The actuarial rate of local prostate cancer control was 98% (95% confidence interval [CI] 94% to 99%). Actuarial disease-specific survival at 3 and 5 years was 89% (95% CI 73% to 96%) and 79% (95% CI 58% to 91%), respectively. At 3 and 5 years, actuarial biochemical disease-free survival was 48% (95% CI 32% to 63%) and 34% (95% CI 17% to 51%), respectively. Post-treatment PSA nadir was found to be a significant predictor of biochemical disease-free survival. Actuarial biochemical disease-free survival of patients who achieved a PSA nadir less than 0.5 ng/mL was 77% (95% CI 53% to 90%) and 56% (95% CI 25% to 78%) at 3 and 5 years, respectively. Of 49 patients, 23 (47%) achieved a post-treatment PSA nadir less than 0.5 ng/mL. The incidence of serious complications after salvage brachytherapy, such as incontinence and rectal complications, was lower than that reported after other types of salvage procedures.

CONCLUSIONS

Interactive transperineal fluoroscopic-guided and biplane ultrasound-guided brachytherapy is a novel, potentially curative salvage modality for patients in whom prior radiotherapy failed. In a population of patients with poor prognosis, this modality was associated with a high rate of local prostate cancer control and a 34% actuarial rate of biochemical disease-free survival at 5 years. The incidence of major complications after salvage brachytherapy appears to be lower than that after other potentially curative salvage procedures, such as radical prostatectomy and cryoablation. Salvage brachytherapy warrants further investigation.

Prehospital discharge defibrillation testing in ICD recipients: a prospective study based on cost analysis

Prehospital discharge defibrillation testing is often performed to verify the function of newly implanted cardioverter defibrillators (ICDs). To determine whether elimination of predischarge testing could reduce costs without placing patients at additional risk, 31 patients were randomized in this prospective clinical evaluation to either receive or not receive a predischarge ICD defibrillation test. Expenses associated with postimplant care was the primary endpoint. All patients underwent induction of ventricular fibrillation after 6 months to evaluate ICD function. The groups were well matched in terms of patient characteristics, initial lead implant parameters, and defibrillation thresholds. Elimination of prehospital discharge testing resulted in a savings of $1,800/patient after 6 months, with no difference between groups in terms of ICD complication rates or unanticipated hospital admissions. Further studies are needed to better define the most appropriate time to assess defibrillation thresholds in the first year after implantation.

Thalidomide does not alter the pharmacokinetics of ethinyl estradiol and norethindrone

OBJECTIVE

To evaluate the effect of thalidomide on the plasma pharmacokinetics of ethinyl estradiol (INN, ethinylestradiol) and norethindrone (INN, norethisterone).

METHODS

Ten women who had undergone surgical sterilization were enrolled in an open-label crossover study conducted in the Georgetown University Clinical Research Center. The pharmacokinetics of single doses of 0.07 mg ethinyl estradiol and 2 mg norethindrone were measured at baseline and after 3 weeks of 200 mg thalidomide. Compliance with the thalidomide regimen was assessed with use of Medication Event Monitoring System (MEMS) caps.

RESULTS

No changes were observed in the pharmacokinetics of ethinyl estradiol or norethindrone with thalidomide therapy. The mean +/- SD area under the plasma concentration-time curve (AUC0-infinity) for ethinyl estradiol was 6580 +/- 1100 ng.h/L at baseline and 5970 +/- 1560 ng.h/L after the thalidomide regimen (paired t test, P > .05). The values for norethindrone were 103 +/- 54 micrograms.h/L and 107 +/- 58 micrograms.h/L (paired t test, P > .05). No changes were observed for other pharmacokinetic parameters assessed for either ethinyl estradiol or norethindrone. No accumulation of thalidomide was seen after 21 days of therapy: day 1 AUC0-infinity 41.1 +/- 13.9 micrograms.h/mL; day 21 AUC0-infinity 59.6 +/- 27.3 micrograms.h/mL (paired t test, P > .05). No changes were observed for other pharmacokinetic parameters assessed for thalidomide between days 1 and 21. Thalidomide was well tolerated but caused variable degrees of sedation. The average thalidomide compliance rate was 97%.

CONCLUSIONS

The pharmacokinetics of thalidomide do not change with 3 weeks of daily dosing. Thalidomide does not alter the pharmacokinetics of ethinyl estradiol or norethindrone. Therefore there is no drug interaction between thalidomide and these 2 drugs. The efficacy of oral contraceptives containing ethinyl estradiol and norethindrone should not be affected by concomitant thalidomide therapy.

Actuarial disease-free survival after prostate cancer brachytherapy using interactive techniques with biplane ultrasound and fluoroscopic guidance

PURPOSE

To evaluate the effectiveness and safety of interactive transperineal brachytherapy under biplane ultrasound and fluoroscopic guidance in patients with localized prostate cancer.

METHODS AND MATERIALS

Brachytherapy using 125I or 103Pd radioactive seeds either alone or in combination with adjunctive external beam radiotherapy (XRT) was administered to 490 patients at a single institution. Post-treatment follow-up included clinical assessment of disease status, assays of serum prostate-specific antigen (PSA) levels and documentation of treatment-related symptoms and complications.

RESULTS

Actuarial disease-free survival at 5 yr was 79% (95% CI, 71-85%), and the 5-yr actuarial rate of local control was 98% (95% CI, 94-99%). Post-treatment PSA nadir and pretreatment PSA level were found to be significant predictors of disease-free survival. In patients with a PSA nadir < 0.5 ng/ml, 5-yr disease-free survival was 93% (95% CI, 84-97%), compared with 25% (95% CI, 5-53%) in patients whose PSA nadir was 0.5-1.0 ng/ml and 15% (95% CI, 3-38) in patients with a PSA nadir > 1.0 ng/ml. Brachytherapy was well tolerated with few post-treatment complications.

CONCLUSION

A broad range of patients with localized prostate cancer can benefit from transperineal brachytherapy with minimal morbidity. A post-treatment PSA nadir below 0.5 ng/ml provides a useful prognostic indicator of favorable long-term outcome.

Meniscal cysts: detection with high-resolution sonography

OBJECTIVE

The purpose of this study was to determine the feasibility of high-resolution sonography for the detection of meniscal cysts and associated meniscal tears and for the differentiation of meniscal cysts from other masses at the knee joint.

SUBJECTS AND METHODS

Fifty consecutive patients (51 knees) with a palpable mass at the knee joint were examined prospectively using a 7.5-MHz annular array transducer. Mass consistency and location and meniscal integrity were evaluated. Sonographic findings were correlated with surgery (46/51) and histopathology (15/51). Five patients did not undergo surgery.

RESULTS

At surgery, 32 masses appeared to be meniscal cysts, whereas 19 were other types of masses. Sonographically, 31 of the 32 meniscal cysts were diagnosed correctly. Sonographic differentiation of the other types of masses from meniscal cysts could reliably be made in 17 of 19 cases; two masses were falsely interpreted as meniscal cysts. Sensitivity, specificity, and accuracy of sonography in the depiction of meniscal cysts were 97%, 86%, and 94%, respectively. The positive predictive value was 94% and the negative predictive value was 92%. Meniscal tears (31/46) and meniscal tears concomitant with meniscal cysts (26/32) were detected with an accuracy of 83% and 88%, respectively.

CONCLUSION

Sonography is an accurate imaging technique for the detection of meniscal cysts and associated meniscal tears. Differentiation of meniscal cysts from other cystic and solid masses at the knee joint can be reliably made with sonography.

Glucuronidation of 3'-azido-3'-deoxythymidine (zidovudine) by human liver microsomes: relevance to clinical pharmacokinetic interactions with atovaquone, fluconazole, methadone, and valproic acid

Zidovudine (3'-azido-3'-deoxythymidine [AZT]), an antiviral nucleoside analog effective in the treatment of human immunodeficiency virus infection, is primarily metabolized to an inactive glucuronide form, GAZT, via uridine-5'-diphospho-glucuronosyltransferase (UGT) enzymes. UGT enzymes exist as different isoforms, each exhibiting substrate specificity. Published clinical studies have shown that atovaquone, fluconazole, methadone, and valproic acid decreased GAZT formation, presumably due to UGT inhibition. The effect of these drugs on AZT glucuronidation was assessed in vitro by using human hepatic microsomes to begin understanding in vitro-in vivo correlations for UGT metabolism. The concentrations of each drug studied were equal to those reported with the usual clinical doses and at concentrations at least 10 times higher than would be expected with these doses. High-performance liquid chromatography was used to assess the respective metabolism and formation of AZT and GAZT. All four drugs exhibited concentration-dependent inhibition of AZT glucuronidation. The respective concentrations of atovaquone and methadone which caused 50% inhibition of GAZT were > 100 and 8 micrograms/ml, well above their usual clinical concentrations. Fluconazole and valproic acid exhibited 50% inhibition of GAZT at 50 and 100 micrograms/ml, which are within the clinical ranges of 10 to 100 and 50 to 100 micrograms/ml, respectively. These data suggest that inhibition of AZT glucuronidation may be more clinically significant with concomitant fluconazole and valproic acid. Factors such as inter- and intraindividual pharmacokinetic variability and changes in AZT intracellular concentrations should be considered as other mechanisms responsible for changes in AZT pharmacokinetics with concomitant therapies.

Physiologic cardiac pacing in patients with contemporary implantable cardioverter-defibrillators

Contemporary implantable cardioverter-defibrillators (ICD) incorporate single-chamber ventricular pacing capability. However, because poor ventricular function and/or congestive heart failure is common in the ICD population, the provision of more "physiologic" pacing modes has been receiving increased attention. To evaluate the potential impact of ICDs with physiologic pacing features, we assessed the frequency with which atrial-based pacing modes with or without rate responsiveness are currently used in ICD recipients. Further, we characterized those clinical variables at initial ICD implant that tended to be associated with subsequent need for physiologic pacing. Clinical findings were reviewed in 250 consecutive patients who received ICDs with VVI pacing capability at the University of Minnesota Cardiac Arrhythmia Center between January 1991 and February 1997. Adjunctive physiologic pacing was undertaken in 35 patients (14%): 13 before or at the same time as their ICD, and 22 within a mean of 2.5 years after initial ICD surgery. A history of atrial tachyarrhythmia before ICD implantation (p <0.0001) and treatment with antiarrhythmic drugs at the time of ICD surgery (p <0.05) were predictors of subsequent need for physiologic pacing. The type of presenting ventricular tachyarrhythmia and electrophysiologic parameters (such as the HV interval and the shortest atrial pacing cycle length associated with 1:1 anterograde atrioventricular conduction) were not associated with a subsequent decision to implant a physiologic pacing system. Thus, we conclude that despite the need to implant a second device, physiologic pacing is currently used in an important subset of ICD recipients. Further, certain clinical features at time of ICD implant appear to characterize these patients and may prove helpful in patient selection for the next generation "dual-chamber" ICD.