Multivariate spatial feature selection in fMRI

Multivariate neuroimaging analyses constitute a powerful class of techniques to identify psychological representations. However, not all psychological processes are represented at the same spatial scale throughout the brain. This heterogeneity is apparent when comparing hierarchically organized local representations of perceptual processes to flexible transmodal representations of more abstract cognitive processes such as social and affective operations. An open question is how the spatial scale of analytic approaches interacts with the spatial scale of the representations under investigation. In this article, we describe how multivariate analyses can be viewed as existing on a spatial spectrum, anchored by searchlights used to identify locally distributed patterns of information on one end, whole brain approach used to identify diffuse neural representations at the other and region-based approaches in between. We describe how these distinctions are an important and often overlooked analytic consideration and provide heuristics to compare these different techniques to choose based on the analyst’s inferential goals.

Response to Lynch et al: On measuring head motion and effects of head molds during fMRI

We recently presented evidence indicating limited efficacy of custom-molded headcases in reducing head motion in two naturalistic experimental contexts - passive movie watching, and speaking in the scanner (Jolly et al., 2020). In a commentary on this work, Lynch et al (2020) present additional data that support the original findings of (Power et al., 2019) and raise several potential issues with our recent work. We appreciate the opportunity to address these criticisms and raise additional points that should be considered when interpreting these conflicting findings. We do not believe that their criticisms diminish the value of our work, but instead, along with this reply, help better elucidate the key factors researchers should consider to make the most informed choice about their own research protocols.

Custom-molded headcases have limited efficacy in reducing head motion during naturalistic fMRI experiments

Effectively minimizing head motion continues to be a challenge for the collection of functional magnetic resonance imaging (fMRI) data. The use of individual-specific custom molded headcases is a promising solution to this issue, but there has been limited work to date. In the present work, we examine the efficacy of headcases in a larger group of participants engaged in naturalistic scanning paradigms including: long movie-watching scans (~20 to 45min) and a recall task that involved talking aloud inside the MRI. Unlike previous work, we find that headcases do not reliably reduce motion during movie viewing compared to alternative methods such as foam pillows or foam pillows plus medical tape. Surprisingly, we also find that motion is worse when participants talk aloud while wearing headcases. These differences appear to be driven by large, brief rotations of the head as well as translations in the z-plane as participants speak. Smaller, constant head movements appear equivalent with or without headcases. The largest reductions in head motion are observable when participants were situated with both foam pillows and medical tape. Altogether, this work suggests that in a healthy adult population, custom-molded headcases may provide limited efficacy in reducing head motion beyond existing tools available to researchers. We hope this work can help improve the quality of custom headcases, motivate the investigation of additional solutions, and provide additional information about head motion in naturalistic contexts.

Screening Tool to Reduce Anticoagulant Clinic Encounters

OBJECTIVE

Patients prescribed warfarin for the prevention of stroke in atrial fibrillation at the Fayetteville Veterans Affairs Heath Care Center are managed by a clinical pharmacy specialist (CPS) in the Anticoagulation Clinic. Patients prescribed a direct oral anticoagulant (DOAC) for the same indication are followed by a CPS within the patient aligned care team. A screening tool was developed to identify candidates who could switch from warfarin to DOAC therapy. The purpose of this quality improvement project was to determine the impact of a screening tool on the average number of monthly Anticoagulation Clinic encounters.

METHODS

The impact of the screening tool to effect the number of clinic encounters was studied for 3 months prior to and 2 months following an 8-week screening period. The screening tool, created to determine the eligibility of patients to switch to DOAC, was developed based on US Department of Veterans Affairs Pharmacy Benefits Management Service guidance. Eligible patients were counseled on DOACs and given the opportunity to shift therapies. The total number of encounters associated with all anticoagulant patients, including those who changed to DOACs, was recorded.

RESULTS

During the 3 months prior to screening, an average of 476 encounters per month were documented. For 2 months following screening, an average of 546 encounters per month were recorded. Seventy additional monthly encounters were observed after the screening tool implementation (P = .15). Thirty patients chose to switch to DOAC therapy; there were 75 fewer encounters among these 30 patients in the postscreening period, a reduction of 70.1% (P = .01).

CONCLUSIONS

The DOAC screening tool was unsuccessful in reducing the overall number of Anticoagulation Clinic encounters. However, it was determined that when patients switched from warfarin to a DOAC, encounters were reduced. Several confounding factors influenced study results.

Parasitaemia data and molecular characterization of Haemoproteus catharti from New World vultures (Cathartidae) reveals a novel clade of Haemosporida

Background

New World vultures (Cathartiformes: Cathartidae) are obligate scavengers comprised of seven species in five genera throughout the Americas. Of these, turkey vultures (Cathartes aura) and black vultures (Coragyps atratus) are the most widespread and, although ecologically similar, have evolved differences in morphology, physiology, and behaviour. Three species of haemosporidians have been reported in New World vultures to date: Haemoproteus catharti, Leucocytozoon toddi and Plasmodium elongatum, although few studies have investigated haemosporidian parasites in this important group of species. In this study, morphological and molecular methods were used to investigate the epidemiology and molecular biology of haemosporidian parasites of New World vultures in North America.

Methods

Blood and/or tissue samples were obtained from 162 turkey vultures and 95 black vultures in six states of the USA. Parasites were identified based on their morphology in blood smears, and sequences of the mitochondrial cytochrome b and nuclear adenylosuccinate lyase genes were obtained for molecular characterization.

Results

No parasites were detected in black vultures, whereas 24% of turkey vultures across all sampling locations were positive for H. catharti by blood smear analysis and/or PCR testing. The phylogenetic analysis of cytochrome b gene sequences revealed that H. catharti is closely related to MYCAMH1, a yet unidentified haemosporidian from wood storks (Mycteria americana) in southeastern USA and northern Brazil. Haemoproteus catharti and MYCAMH1 represent a clade that is unmistakably separate from all other Haemoproteus spp., being most closely related to Haemocystidium spp. from reptiles and to Plasmodium spp. from birds and reptiles.

Conclusions

Haemoproteus catharti is a widely-distributed parasite of turkey vultures in North America that is evolutionarily distinct from other haemosporidian parasites. These results reveal that the genetic diversity and evolutionary relationships of avian haemosporidians are still being uncovered, and future studies combining a comprehensive evaluation of morphological and life cycle characteristics with the analysis of multiple nuclear and mitochondrial genes will be useful to redefine the genus boundaries of these parasites and to re-evaluate the relationships amongst haemosporidians of birds, reptiles and mammals.

Electronic supplementary material

The online version of this article (10.1186/s12936-017-2165-5) contains supplementary material, which is available to authorized users.

The psychometric properties of patient preferences in osteoporosis

OBJECTIVE

Osteoporosis is a chronic disease manifested by wrist, vertebral, and hip fractures that results in significant morbidity and burden to society. About 30% of postmenopausal women have osteoporosis according to the WHO criteria. Women with one vertebral fracture have a 4-fold increased risk of a subsequent fracture. The goal of treatment is to prevent fractures and improve quality of life. Preferences or utilities are now recommended for incorporating quality of life into evaluations of the cost effectiveness of new therapeutic interventions. We evaluated the psychometric properties of preference based measures in osteoporosis.

METHODS

Preference scenarios were constructed with a health state classification system. The reliability and validity of the feeling thermometer and the standard gamble was assessed by interviewing 42 women from 4 different patient groups. The sensitivity to change of the feeling thermometer and standard gamble was compared with the Health Utilities Index Mark 2 (HUI2) and SF-36. All subgroups were reassessed about 2 months after their first interview.

RESULTS

Preference measurement was feasible in women of different age groups. The reliability coefficients for health states ranged from 0.65 to 0.87. The preference scores for the marker states demonstrated content validity. Convergent validity of the feeling thermometer was supported by a significant correlation with the HUI2 (r = 0.38, p < 0.05) and the physical health summary of the SF-36 (r = 0.56, p < 0.005). The standard gamble did not correlate with the HUI2 (r = 0.15) or the feeling thermometer (r = 0.09), but correlated with 2 domains of the SF-36. The preference measures were sensitive to change, with the efficiency scores ranging from 0.78 to 1.0.

CONCLUSION

Preference measurements in the evaluation of osteoporosis are feasible. The feeling thermometer and standard gamble appear to be related to different aspects of health related quality of life. Both instruments were sensitive to change over a 2 month period.

Uterine effects of raloxifene in comparison with continuous-combined hormone replacement therapy in postmenopausal women

OBJECTIVE

We sought to compare the uterine effects of raloxifene with those of continuous-combined hormone replacement therapy.

STUDY DESIGN

This randomized, double-blind 24-month study involved 136 postmenopausal women who received raloxifene 150 mg/d or conjugated equine estrogens 0.625 mg/d with medroxyprogesterone acetate 2.5 mg/d. After baseline evaluations, endometrial biopsy specimens were obtained, and endometrial thickness was measured annually by means of transvaginal ultrasonography. Statistical analyses were performed with an intention-to-treat approach.

RESULTS

In the raloxifene group at the end point of the study 94.4% of biopsy specimens showed normal benign postmenopausal endometrium and 5.6% were classified as benign stimulatory endometrium. In the continuous-combined hormone replacement therapy group at the end point of the study 78.7% of biopsy specimens showed normal benign postmenopausal endometrium, 19. 1% were classified as benign stimulatory endometrium, and 2.1% showed benign abnormal postmenopausal endometrium. Mean endometrial thickness was unchanged from baseline with raloxifene and was increased significantly by 0.5 mm at 12 months with continuous-combined hormone replacement therapy.

CONCLUSION

Raloxifene 150 mg/d did not increase endometrial thickness or cause endometrial proliferation in healthy postmenopausal women.

Randomized trial of a portable, self-administered decision aid for postmenopausal women considering long-term preventive hormone therapy

Although practice guidelines suggest that postmenopausal women learn about the benefits and risks and consider their values when deciding about hormone therapy, the optimal decision-support method has not been established. In a randomized controlled trial, the authors compared the efficacy of a general educational pamphlet with that of a tailored decision aid. The pamphlet briefly summarized benefits, risks, and likely beneficiaries in general terms. The decision aid, delivered via booklet and audiotape, provided: detailed benefits and risks using functional terms and probabilities tailored to clinical risk; and steps for considering the issue in a woman's own situation, including a value-clarification exercise. Compared with the pamphlet group, the decision-aid group had statistically significant (p < 0.05) improvements in terms of realistic personal expectations of the benefits and risks, decisional conflict, and perceived acceptability of the intervention. Levels of general knowledge about the main benefits and risks were comparable for the two interventions. It is concluded that tailored decision aids prepare women for decision making better than do general pamphlets.

A decision aid for women considering hormone therapy after menopause: decision support framework and evaluation

Although postmenopausal women are advised to consider their values when deliberating about potential benefits and risks of hormone therapy (HRT), feasible, effective methods of decision support in primary care have yet to be established. Using an explicit decision support framework, we developed a self-administered HRT decision aid and evaluated it in a before/after study of 94 women from six family practices. An audiotape guided women through an illustrated booklet including: detailed information about HRT benefits and risks tailored to a woman's clinical risk, and a values clarification exercise to promote informed decision making consistent with personal values. After using the decision aid participants: had better general knowledge and more realistic personal expectations of HRT benefits and risks; and, felt more certain, informed, clear about values, and supported in decision making. Women's values elicited in the clarification exercise were 84% accurate in discriminating between decisions. Women with polarized preferences at baseline did not change their minds, but were better informed. Changes in preferences occurred in the uncertain group, with equal numbers accepting or declining HRT. Most participants found the decision aid comprehensible, acceptable in length and pace, and balanced. Decision aids are useful in preparing women for decision making about this complex, personal issue.

[Acute effect of lorazepam on respiratory muscles in stable patients with chronic obstructive pulmonary disease]

Benzodiazepines are known to cause muscle hypotonia, but their effects on respiratory muscle function, particularly on diaphragm, have not yet been studied. Our aim was to look for any effect of lorazepam on respiratory muscle function in patients with chronic obstructive pulmonary disease (COPD). Nine stable COPD patients (mean +/- SD forced expiratory volume in one second (FEV1) 0.91 +/- 0.31 l) were included in the study. The following measurements were performed before and 1 hour after lorazepam administration (doses: 1.5 to 2 mg) by sublingual route: forced vital capacity (FVC), FEV1, maximal voluntary ventilation (MVV), arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), minute ventilation (Ve), tidal volume (Vt), respiratory rate (f), inspiratory time/inspiratory plus expiratory time (Ti/Ttot)-, mean inspiratory flow (Vi), maximal inspiratory (MIP) and expiratory (MEP) pressures, maximal pleural pressure (Pplmax), transdiaphragmatic pressures (Pdi) and skeletal muscle strength and endurance. As expected, no change was noted in FVC, FEV1, FEV1/FVC (Table-1). Besides stability of expiratory flows, this denotes no change in collaboration in spite of the sedative effects of lorazepam. There was a 20% decrease in Ve, due to a Vt reduction and a small increase in PaCO2. These could be explained by the central effects of benzodiazepines. Skeletal muscle strength and endurance decreased significantly (22 and 50% respectively-Table 2), in accordance with the previously reported muscular actions of this pharmacological group. Respiratory muscle function parameters, MIP, MEP, MVV and Ppl showed significant reductions (10 to 20 per cent), as was the case with diaphragmatic function measured by Pdi (Muller maneuver with abdominal protrussion and maximal open-glottis expulsive maneuver) (Table 3). This study demonstrates that a single lorazepam dose reduces strength and endurance of respiratory muscle in chronic stable COPD patients.

Primary thrombocythemia in pregnancy: a report of two cases

We report two cases of primary thrombocythemia diagnosed during pregnancy. One patient developed transient visual field defects. She was treated with plateletpheresis at term and delivered of a normal child by cesarean section. The second patient was not treated. Intrauterine fetal death occurred at 36 weeks' gestation from multiple placental infarcts. In cases of primary thrombocythemia, we suggest close monitoring of both mother and fetus throughout pregnancy.

Genetic counseling, a health department service to physicians

Questions about inheritance in all kinds of diseases and defects are commonly asked of nearly all physicians. In attempting to answer these questions, however, the physician is often hampered by lack of formal instruction in clinical genetics. Since the health department, if it is to carry out its epidemiologic function, must be as concerned over the increasing identification of genetic agents in disease as it is and has been over environmental disease agents, it should come to represent a source of assistance not now generally available to the physician. In short, as it carries out those activities by which its store of general genetic information is increased, and until other sources of genetic consultation become reasonably available, the health department can be of real service to physicians as a resource to which they may turn for help when dealing with families wanting genetic information. Such a service has been provided experimentally for the last two years by the Contra Costa County Health Department. This program calls for the taking of family pedigrees by public health nurses on families with questions of a genetic nature who are health department clients and on families who are referred by their private physicians for this service. An interpretation of each pedigree is made by the department's physician in charge of the program and submitted to the family's physician for his use in counseling the family. Evidence to date suggests the process can be a highly useful service to the practitioner and his patient.