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Biomedical subjects

P Fox

Publications and source records attributed to P Fox.

At least 37 records · Page 2Linked to original sources
PubMed2000

Functional imaging of brain areas involved in the processing of coherent and incoherent wide field-of-view visual motion.

The brain areas involved in processing wide field-of-view (FOV) coherent and incoherent visual stimuli were studied using positron emission tomography (PET). The brains of nine subjects were scanned as they viewed texture patterns moving in the roll plane. Five visual conditions were used: (1) coherent clockwise (CW) wide-FOV (>100 degrees) roll motion; (2) coherent counter-clockwise (CCW) wide-FOV roll motion; (3) wide-FOV incoherent motion; (4) CCW motion confined to the central visual field (approximately 55 degrees); and (5) a stationary control texture. The region most activated by the coherent-motion stimulus relative to the static one was the medial-occipital cortex, whereas both the medial- and lateral-occipital cortices were activated by incoherent motion relative to a static texture. Portions of the retroinsular parietal-temporal cortex, superior insula, putamen, and vestibulocerebellum responded specifically to the coherence of the stimulus, whereas a widespread lateralized activation was observed upon subtracting the CW scans from the CCW scans. The results indicate separate neural regions for processing wide-FOV motion versus stimulus coherence.

Adult↗
PubMed2000

Population aging and the need for long term care: a comparison of the United States and the People's Republic of China.

Both developing and major developed countries of the world are facing the global aging of their citizenry. The United States and the People's Republic of China each share in this phenomenon. The rapid growth of their aging populations comes as both countries are experiencing a sustained period of economic stability with an accompanying drop in fertility rates (Coale & Watkins 1986; Dyson & Murphy 1985). Together with longer expected life spans in both countries, these factors have caused a shift in the population structure which will result in increasingly large portions of the population who will potentially require assistance with ADL's and/or long term care (Olson 1990; Kennedy, LaPlante & Kaye 1997). The careful assessment and interpretation of available data to define the actual extent of need should be part of a process to help guide each country as they prepare for the future.

Journal Article↗
PubMed2000

Effectiveness of a bed positioning program for treating older adults with knee contractures who are institutionalized.

BACKGROUND AND PURPOSE: Although contractures in patients in long-term care institutions are an important issue, there have been only a few studies that have evaluated interventions for contractures. The purpose of this study was to determine the effectiveness of a bed positioning program (BPP) for the treatment of patients with knee flexion contractures. SUBJECTS: Sixteen patients with a high level of cognitive and functional impairment (mean age=82 years, SD=6.48, range=71-93) in a chronic care hospital participated in the study. METHODS: The BPP consisted of stretching a patient's knee into extension and then securing and maintaining the position for a period of 40 minutes, 4 times per week. Participants were randomly assigned to 2 groups (n=8 in each group). One group received a BPP for 8 weeks, followed by 8 weeks of no intervention. The other group received the intervention in the reverse order. Once a week, participants were assessed for range of knee extension, knee pain, and skin integrity. RESULTS: Twelve participants completed the study. There was no improvement in participants' range of knee extension during the intervention period. Overall, there was no difference in mean range of knee extension between the intervention period and the no-intervention period. CONCLUSION AND DISCUSSION: The results of this study do not support the use of a BPP for treating patients with knee flexion contractures.

Aged↗
PubMed2000

Language mapping in pretreatment planning of patients with cerebral arteriovenous malformation: a PET study.

PURPOSE: Three patients who had cerebral arteriovenous malformations underwent language mapping by positron emission tomography (PET) to identify the dominant hemisphere for language and the spatial relation of lesions to language areas. METHODS: Mapping was performed to assess the risk that surgery could cause neurologic deficits and to plan other therapeutic strategies. RESULTS: The information obtained by PET language mapping changed the course of management for these patients. Two patients were treated with stereotactic radiosurgery and one patient with surgical resection. CONCLUSIONS: PET imaging can be a valuable noninvasive tool for mapping the functional cortex and for preoperative planning of different treatment options in patients with arteriovenous malformations.

Adolescent↗
PubMed2000

Efficiency and sustainability of soil-aquifer treatment for indirect potable reuse of reclaimed water.

An increasing number of municipalities are considering the indirect reuse of treated wastewater (recycled water) by groundwater recharge as a feasible option to augment potable water supplies. This planned approach offers several advantages compared to the conventional way of discharging effluents into surface waters, including the additional treatment afforded as the water percolates and co-mingles with groundwater (soil aquifer treatment). While groundwater recharge has been used in the United States (U.S.) for several decades and has been the subject of a number of studies, limitations in methodology and testing have prevented many within the scientific and technical community from being able to fully address a number of complex public health questions related to organic chemicals, nitrogen and microorganisms. Ongoing research being conducted in Arizona and California is directed at reducing the uncertainties about the efficiency and sustainability of soil aquifer treatment for indirect potable reuse of recycled water.

Conservation of Natural Resources↗
PubMed2000

Evaluation of octree regional spatial normalization method for regional anatomical matching.

The goal of regional spatial normalization is to remove anatomical differences between individual three-dimensional (3D) brain images by warping them to match features of a standard brain atlas. Processing to fit features at the limiting resolution of a 3D MR image volume is computationally intensive, limiting the broad use of full-resolution regional spatial normalization. In Kochunov et al. (1999: Neuro-Image 10:724-737), we proposed a regional spatial normalization algorithm called octree spatial normalization (OSN) that reduces processing time to minutes while targeting the accuracy of previous methods. In the current study, modifications of the OSN algorithm for use in human brain images are described and tested. An automated brain tissue segmentation procedure was adopted to create anatomical templates to drive feature matching in white matter, gray matter, and cerebral-spinal fluid. Three similarity measurement functions (fast-cross correlation (CC), sum-square error, and centroid) were evaluated in a group of six subjects. A combination of fast-CC and centroid was found to provide the best feature matching and speed. Multiple iterations and multiple applications of the OSN algorithm were evaluated to improve fit quality. Two applications of the OSN algorithm with two iterations per application were found to significantly reduce volumetric mismatch (up to six times for lateral ventricle) while keeping processing time under 30 min. The refined version of OSN was tested with anatomical landmarks from several major sulci in a group of nine subjects. Anatomical variability was appreciably reduced for every sulcus investigated, and mean sulcal tracings accurately followed sulcal tracings in the target brain.

Algorithms↗
PubMed2000

Is "ambient vision" distributed in the brain? Effects of wide-field-view visual yaw motion on PET activation.

Ambient vision comprises the visual functions that are associated with the maintenance of spatial orientation and that depend on peripheral, preconscious visual inputs. Although a limited number of brain areas appear to be activated by coherent wide-field-of-view (WFOV) motion in more than one axis, a diffuse pattern of lateralized brain activity occurs in response to clockwise or counterclockwise ambient visual roll motion. In the present study involving positron emission tomography (PET), a similar finding was shown for rightward versus leftward yaw stimulation. A total of 18 PET scans were obtained from six subjects in response to either leftward or rightward WFOV motion in a collimated display subtending > 100 degrees horizontally. Rightward stimulation elicited mainly activation throughout the right hemisphere, whereas leftward stimulation elicited mainly activation throughout the left hemisphere. These findings provide further evidence that the ambient vision signal is either processed or transmitted throughout the entire brain, as befits a visual function that is fundamental to all other perceptual systems.

Adult↗
PubMed1999

Highly active anti-retroviral therapy (HAART) prolongs time to treatment failure in Kaposi's sarcoma.

OBJECTIVE: To evaluate the impact of highly active antiretroviral therapy (HAART) on Kaposi's sarcoma. DESIGN: Retrospective study of patients who had received systemic or local treatment for AIDS-related Kaposi's sarcoma who subsequently commenced HAART. METHODS: Case note review to determine time to treatment failure for Kaposi's sarcoma before and after starting HAART. Time to treatment failure was calculated from the end of last therapy to the start of the next new treatment for Kaposi's sarcoma. RESULTS: The cohort contained 78 patients. Only 38% had good risk Kaposi's sarcoma (stage T0I0) at presentation. The median time to treatment failure before starting HAART was 0.5 years. Initial HAART therapy was three or more drugs including a protease inhibitor for 38 (49%), three or more drugs without a protease inhibitor for 27 (35%) and a two-drug protease combination for 13 (16%). The median follow-up after starting HAART was 12 months (range, 0.5-52 months) and anti-Kaposi's sarcoma treatment has been required for 24 (31%) patients. The median time to treatment failure for Kaposi's sarcoma from the start of HAART is 1.7 years. This is statistically longer than the time to treatment failure for the same cohort of patients before they started HAART (log rank chi2 = 16.5, P < 0.0001). The serum HIV RNA viral load (VL) at the time of Kaposi's sarcoma progression revealed virological failure of HAART (defined as VL > 5000 copies/ml) in 14 of 24 (58%) and good control (VL < 200 copies/ml) in five of 24 (21%). CONCLUSION: HAART is associated with prolonged time to treatment failure in Kaposi's sarcoma. Progression of Kaposi's sarcoma while on HAART is not necessarily associated with virological failure as determined by rising viral RNA titre.

Adult↗
PubMed1999

Neuroimaging of genesis and satiation of thirst and an interoceptor-driven theory of origins of primary consciousness.

There are defined hypothalamic functions in the genesis of thirst, but little is known of the cortical processes subserving consciousness of thirst notwithstanding the medical disorders that occur in psychiatric illness, addiction, and the attested decline of thirst with aging. In 10 adult males, positron emission tomography scans were made (i) during genesis of moderate thirst by infusion of i.v. hypertonic saline 0.51 M, (ii) after irrigation of the mouth with water to remove the sensation of dryness, and (iii) 3, 14, 45, and 60 minutes after drinking water to fully satiate thirst. The correlation of regional cerebral blood flow with thirst score showed the major activation to be in the posterior cingulate. Maximum thirst sensation evoked 13 highly significant activations and 9 deactivations in cingulate and parahippocampal gyri, insula, thalamus, amygdala, and mesencephalon. It is possible that cingulate sites (Brodmann's areas 32, 24, and 31) that persisted with wet mouth but disappeared immediately after drinking to satiation may have an important role in the consciousness of thirst. Consciousness of thirst, a primal vegetative emotion, and satiation of thirst appear to be subserved by phylogenetically ancient brain regions. This is salient to current discussion on evolutionary emergence of primary consciousness.

Adult↗
PubMed1999

Correlation of regional cerebral blood flow and change of plasma sodium concentration during genesis and satiation of thirst.

Positron emission tomography studies were conducted during genesis of moderate thirst by rapid i.v. infusion of hypertonic saline (0.51 M) and after satiation of thirst by drinking water. The correlation of regional cerebral blood flow with the change in the plasma Na concentration showed a significant group of cerebral activations in the anterior cingulate region and also a site in the middle temporal gyrus and in the periaqueductal gray. Strongest deactivations occurred in the parahippocampal and frontal gyri. The data are consistent with an important role of the anterior cingulate in the genesis of thirst.

Adult↗
PubMed1999

Anniversary reactions in Gulf War veterans: a follow-up inquiry 6 years after the war.

OBJECTIVE: The goal of this study was to assess the occurrence of anniversary reactions in Gulf War veterans 6 years after the conclusion of the war. METHOD: Subjects were administered questionnaires and asked to identify specific months of best and worst functioning and months of least or most symptoms of posttraumatic stress disorder (PTSD) for the 12 months before the study. Months of negative experiences were compared with previously documented dates of exposure to traumatic events during the war. Similar reports were also obtained from the veterans' spouses in order to assess corroborative evidence for the occurrence of anniversary reactions. RESULTS: Anniversary reactions occurred with a frequency greater than chance and most often in individuals exposed to a greater number of traumatic events. Overall, spouse reports matched the veterans' reports of anniversary reactions. In addition, spouses identified anniversary reactions that were not endorsed by their veterans. CONCLUSIONS: These data suggest that anniversary reactions occur in numbers greater than those expected by chance, are correlated to the occurrence of traumatic events, and may be a part of the syndrome of PTSD.

Adjustment Disorders↗
PubMed1999

Effects of the Medicare Alzheimer's Disease Demonstration on the use of community-based services.

STUDY QUESTION: Did the Medicare Alzheimer's Disease Demonstration with its case management and community service waivers affect the use of community-based long-term care services among people with dementia and their primary caregivers? DATA SOURCES: Baseline and periodic caregiver interviews. Measures include client and caregiver attributes and self-reported service use. STUDY DESIGN: The demonstration randomly assigned voluntary applicants into treatment and control groups. Treatment group cases were eligible for case management and for up to $699 per month in community care benefits. The actual monthly entitlement varied among the eight demonstration communities due to regional cost and inflation adjustments over time. Analyses are for the year after enrollment. DATA COLLECTION: Analyses are of cases surviving six months or more in the community after enrollment (n = 5,209). Cases received baseline and semi-annual assessments. PRINCIPAL FINDINGS: The intervention of case management and community service reimbursement had a strong, consistent, and positive effect on the likelihood of using home care (including homemaker/chore services, personal care services, companion services) and adult day care. Treatment group clients were at least twice as likely as control group clients to be using any of the four community-based services. A similar, but less pervasive effect was achieved with caregiver training and support group participation. Reimbursement provided by the demonstration's Medicare waiver was generally not sufficient to exceed the level of control group service acquired through private payment. CONCLUSIONS: Reimbursement levels within the demonstration may have enabled more individuals to purchase some services, but they were not sufficient to increase the average level of use over those in the control group. No consistent differences between demonstration models were found in service use likelihood or average use among users.

Aged↗
PubMed1999

Effects of the Medicare Alzheimer's Disease Demonstration on caregiver burden and depression.

STUDY QUESTION: Does improved access to community-based care reduce perceived burden and reported levels of depression among primary caregivers of people with dementia? DATA SOURCES: Baseline and periodic caregiver interviews with participants in the Medicare Alzheimer's Disease Demonstration. Client and caregiver attributes and caregiver outcomes such as depression and burden scores were among the measures. STUDY DESIGN: Applicants to the demonstration (all voluntary) were randomly assigned into treatment and control groups. Treatment group cases were eligible for case management and for up to $699 per month in community care benefits. (The actual monthly entitlement varied among the eight demonstration communities due to regional cost differences and inflation adjustments over the four-year demonstration period.) DATA COLLECTION: A total of 5,307 eligible individuals received a baseline assessment at the time of application to the demonstration and at least one semi-annual reassessment. Clients and their caregivers were periodically reassessed producing a total of 20,707 observations. PRINCIPAL FINDINGS: Persons in the treatment group had a high exposure to case management and a greater likelihood of community service use relative to those in the control group. Treatment group membership was associated with statistically significant, but very small reductions in caregiver burden (in four of eight sites) and depression (three of eight sites) over a 36-month tracking period. These findings are not sustained with all cases combined, or among a higher-resource demonstration model considered separately. CONCLUSIONS: Both the fact that these programmatic differences did not translate into substantial treatment group reductions in caregiver burden or depression, and the consistency of these findings with those of prior case management evaluations suggest the need to reformulate this programmatic intervention into areas not previously tested: 24-hour care, crisis intervention, coordination with primary care, or chronic disease management.

Aged↗
PubMed1999

Effects of the Medicare Alzheimer's Disease Demonstration on nursing home entry.

STUDY QUESTION: Did the Medicare Alzheimer's Disease Demonstration, with its goal of improving caregiver outcomes through case management and subsidized community services, affect the nursing home entry rate of treatments with dementia compared to controls? DATA SOURCES: Interviews conducted at baseline and six months thereafter. Measures include date of nursing home entry, client and caregiver health, and income. STUDY DESIGN: The demonstration randomly assigned voluntary applicants into treatment and control groups. Treatment group cases were eligible for case management and for an 80 percent discount on community care benefits, up to about $600 per month. DATA COLLECTION: All cases received baseline and semi-annual assessment interviews for up to three years after enrollment. Analyses are among cases that remained in the demonstration for more than 30 days after enrollment (n = 8,095). PRINCIPAL FINDINGS: The intervention of case management and subsidized community service had no effect on nursing home entry rates for treatments overall, compared to those of controls, and few effects on treatment subgroups, with the exception of one site where it may have increased nursing home entry rates. CONCLUSIONS: Providing case management and subsidized community services with the goal of improving caregiver outcomes may have little effect on nursing home entry rates for people with dementia.

Adult↗
PubMed1999

Case manager-defined roles in the Medicare Alzheimer's Disease Demonstration: relationship to client and caregiver outcomes.

This study explores the different approaches to case management within, the Medicare Alzheimer's Disease Demonstration. Eight sites from around the country were selected to participate in a survey of case managers (N = 57) that evaluated their professional background and experience and how certain tasks, functions, and goals of case management were prioritized at each site. Client and caregiver outcomes were collected on a site-by-site basis as part of the demonstration. The hypothesis was that the way in which case managers performed their work would vary by site. Furthermore it was hypothesized that these differences would be measurable and correlated with project outcomes. Case managers differed significantly by site in how they prioritized tasks, functions, and goals, viewing themselves along a continuum from a clinical approach to one that emphasizes service management. These differences in case management style are reflected in between-site differences in certain client and caregiver outcomes but not others. Specifically, variations in case management style are not related to client cognitive or functional status but to other outcomes including behavioral management, caregiver burden, and service use.

Alzheimer Disease↗
PubMed1999

Effects of the Medicare Alzheimer's disease demonstration on Medicare expenditures.

Applicants were randomized either into a group with a limited Medicare community care service benefit and case management or into a control group receiving their regular medical care. Analyses assess whether or not community care management affected health care use. A tendency toward reduced expenditures was observed for the treatment group, combining all demonstration sites, and when observing each separately. These differences were or approached statistical significance in two sites for Medicare Part A and Parts A and B expenditures averaged over 3 years. Expenditure reductions approached budget neutrality with program costs in two sites.

Adult↗
PubMed1999

Long-term care eligibility criteria for people with Alzheimer's disease.

Long-term care (LTC) eligibility criteria are applied to a sample of 8,437 people with dementia enrolled in the Medicare Alzheimer's Disease Demonstration. The authors find that mental-status-test cutoff points substantially affect the pool of potential beneficiaries. Functional criteria alone leave out people with relatively severe dementia and with behavioral problems. It is therefore important to consider both behavioral and mental-status-test criteria in establishing eligibility for community-based services for people with dementia.

Activities of Daily Living↗