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Biomedical subjects

J Fisk

Publications and source records attributed to J Fisk.

12 recordsLinked to original sources
PubMed2006

Clinical field testing of vulcanized rubber feet for trans-tibial amputees in tropical low-income countries.

In a prospective, controlled study, 186 prosthetic rubber feet of different designs were fitted to amputees with trans-tibial prostheses. There were 158 amputees available for follow-up. The amputee compliance was good and 89% were satisfied with their device. After 18 months of use one VI-Solid rubber foot from VVAF in Cambodia had failed, as compared to 11% failures with the same foot with a heel cavity, 3% with the EB-1 sandwich construction from POF in Vietnam, all performing significantly better than the 62% encountered with the vulcanized rubber foot from ICRC in Cambodia; the latter representing half of the feet failing in amputees walking bare-footed. Nearly all failures were located at the foot-sole or the keel. The failure rate was 20% for the HI-Cambodia foot after 12 months. After 24 months of use, still only one VI-Solid rubber foot had failed and this foot design was found superior to the others in regard of durability.

Adolescent↗
PubMed2002

The effect of the living situation on the severity of dementia at diagnosis.

INTRODUCTION: Previous studies have shown that social determinants not directly involved in the disease process may be implicated in the timing of dementia diagnosis. This study explores the relationship between a patient's living situation and the severity of dementia at diagnosis. METHODS: Data were collected from the baseline interviews of 1,325 patients with cognitive decline enrolled in the Consortium for the Investigation of Vascular Impairment of Cognition study. Data collected included: age, sex, living situation and scores on the Mini-Mental State Examination (MMSE), Global Deterioration Scale (GDS), the Functional Rating Scale (FRS), the Disability Assessment for Dementia (DAD) scale and the Cumulative Illness Rating Scale (CIRS). Living situation was grouped as: (1) lives alone, (2) lives with spouse, (3) lives with child, relative or other and (4) lives in a nursing home. A general linear model univariate analysis was used to compare patients by their respective living situations for differences in mean scores on each of the 4 measures of dementia severity. RESULTS: Statistical analysis of both unadjusted data and data adjusted for age, sex and CIRS scores showed significant differences among the groups. Those who lived alone were diagnosed at an earlier stage (mean scores: MMSE 21.4, GDS 3.6, FRS 20.0, DAD 29.8) followed by those who lived with a spouse (mean scores: MMSE 20.5, GDS 3.7, FRS 20.4, DAD 28.0), those who lived with a child or other (mean scores: MMSE 19.3, GDS 3.9, FRS 22.5, DAD 24.9) and finally those who lived in a nursing home (mean scores: MMSE 15.2, GDS 4.8, FRS 27.5, DAD 16.9). CONCLUSION: Living situation is related to the severity of dementia at diagnosis. Primary care providers should have a low threshold for case-finding in older adults who live with family or friends.

Aged↗
PubMed2001

Tympanic membrane vs. pulmonary artery thermometry.

Studies that compare tympanic membrane thermometry with other thermometry methods conflict. Research at this facility suggests clinically significant discrepancies, which preclude expanding its tympanic thermometer use.

Bias↗
PubMed1999

Roles of p53 and caspases in the induction of cell cycle arrest and apoptosis by HIV-1 vpr.

The vpr gene from the human immunodeficiency virus type-1 (HIV-1) encodes a 14-kDa protein that prevents cell proliferation by causing a block in the G(2) phase of the cell cycle. This cellular function of vpr is conserved in evolution because other primate lentiviruses, including HIV-2, SIV(mac), and SIV(agm) encode related genes that also induce G(2) arrest. After G(2) arrest, cells expressing vpr undergo apoptosis. The signaling pathways that result in vpr-induced cell cycle arrest and apoptosis have yet to be determined. The p53 tumor suppressor protein is involved in signaling pathways leading to cell cycle arrest and apoptosis in a variety of cell types. In this work, we examine the potential role of p53 in mediating cell cycle block and/or apoptosis by HIV-1 vpr and demonstrate that both phenomena occur independently of the presence and function of p53. Caspases are common mediators of apoptosis. We examined the potential role of caspases in mediating vpr-induced apoptosis by treating vpr-expressing cells with Boc-D-FMK, a broad spectrum, irreversible inhibitor of the caspase family. Boc-D-FMK significantly reduced the numbers of apoptotic cells induced by vpr. Therefore, we conclude that vpr-induced apoptosis is effected via the activation of caspases.

Amino Acid Chloromethyl Ketones↗
PubMed1999

The risk of dementia and death after delirium.

BACKGROUND: delirium is common and is associated with many adverse short-term consequences. OBJECTIVES: to examine the relationship between an episode of delirium and subsequent dementia and death over 3 years. DESIGN: prospective cohort study. SETTING: patients (n = 203) were aged 65 years or older at baseline and survivors of the index admission. METHODS: Using a standard assessment of cognitive function, we followed 38 inpatients diagnosed with delirium (22 with delirium and dementia, 16 with delirium only) and 148 patients with no delirium or dementia, for a median of 32.5 months. Follow-up was by personal interviews, supplemented by standardized clinical examinations. We calculated the incidence and odds of dementia and the incidence and hazard ratio for death, with adjustment for potential confounders. RESULTS: The incidence of dementia was 5.6% per year over 3 years for those without delirium and 18.1% per year for those with delirium. The unadjusted relative risk of dementia for those with delirium was 3.23 (95% confidence interval 1.86-5.63). The adjusted relative risk of death also increased (1.80; 1.11-2.92), while the median survival time was significantly shorter in those with (510 days; 433-587) than in those without delirium (1122 days; 922-1322). CONCLUSION: delirium appears to be an important marker of risk for dementia and death, even in older people without prior cognitive or functional impairment.

Aged↗
PubMed1999

Lentivirus vectors using human and simian immunodeficiency virus elements.

Lentivirus vectors based on human immunodeficiency virus (HIV) type 1 (HIV-1) constitute a recent development in the field of gene therapy. A key property of HIV-1-derived vectors is their ability to infect nondividing cells. Although high-titer HIV-1-derived vectors have been produced, concerns regarding safety still exist. Safety concerns arise mainly from the possibility of recombination between transfer and packaging vectors, which may give rise to replication-competent viruses with pathogenic potential. We describe a novel lentivirus vector which is based on HIV, simian immunodeficiency virus (SIV), and vesicular stomatitis virus (VSV) and which we refer to as HIV/SIVpack/G. In this system, an HIV-1-derived genome is encapsidated by SIVmac core particles. These core particles are pseudotyped with VSV glycoprotein G. Because the nucleotide homology between HIV-1 and SIVmac is low, the likelihood of recombination between vector elements should be reduced. In addition, the packaging construct (SIVpack) for this lentivirus system was derived from SIVmac1A11, a nonvirulent SIV strain. Thus, the potential for pathogenicity with this vector system is minimal. The transduction ability of HIV/SIVpack/G was demonstrated with immortalized human lymphocytes, human primary macrophages, human bone marrow-derived CD34(+) cells, and primary mouse neurons. To our knowledge, these experiments constitute the first demonstration that the HIV-1-derived genome can be packaged by an SIVmac capsid. We demonstrate that the lentivirus vector described here recapitulates the biological properties of HIV-1-derived vectors, although with increased potential for safety in humans.

Animals↗
PubMed1998

Establishment and characterization of primary gallbladder epithelial cell cultures in the prairie dog.

BACKGROUND: The prairie dog has become the established animal gallstone model. This species has a unique propensity to form cholesterol gallstones in response to dietary manipulations. The development of a reliable gallbladder cell culture technique is critical for understanding pathogenic mechanisms of gallstone formation. MATERIALS AND METHODS: Prairie dogs underwent laparotomy and cholecystectomy, followed by initiation of cell cultures. [3H]Thymidine incorporation was used to assess cell growth, and cell lines were assessed using routine histochemical and immunohistochemical staining. RESULTS: Cell yields from prairie dog gallbladders were 4-8 x 10(6) viable cells per animal with viability ranging from 80 to 95%. When plated at 5 x 10(5) cells/cm2, cell clusters, visible within 24 h, coalesced into confluent monolayers within 3-5 days. Cultures remained viable for 6-8 weeks and could be passed for three to four subcultures. Immunohistochemical staining demonstrated a high degree of epithelial purity with immunopositivity for AE1/AE3, and cytokeratin, with no vimentin positivity (mesenchymal antigen). Intracytoplasmic vacuoles demonstrated positive staining for Alcian blue, periodic acid-Schiff, and mucicarmine and an anti-gallbladder mucin antibody confirmed the presence of the glycoprotein mucin. CONCLUSIONS: This study demonstrates a reliable method for initiation and maintenance of prairie dog gallbladder epithelial cell cultures with a high degree of purity. This technique should allow further studies into the pathogenesis of cholesterol gallstones in this model.

Animals↗
PubMed1993

Design for the elderly: a biological perspective.

In past times growing old has been synonymous with increasing disability, so that the old have been seen as sans everything. But it is argued here that old age no longer needs to be a time of greater disability, especially if the lifestyles of children and adults are made as healthy as those in less industrialized nations. Design for old age should consder the effects of ageing tissues and common chronic diseases, but, more importantly, should empower the elderly person so that they may continue a dignified, productive life.

Journal Article↗
PubMed1993

Gravitoinertial force level influences arm movement control.

1. The ability to move the forearm between remembered elbow joint angles immediately after rapid increases or decreases of the background gravitoinertial force (G) level was measured. The movements had been well-practiced in a normal 1G environment before the measurements in high-(1.8G) and low-force (0G) environments. The forearm and upper arm were always unsupported to maximize the influence of altered G-loading and to minimize extraneous cues about arm position. 2. Horizontal and vertical movement planes were studied to measure the effects of varying the G load in the movement plane within a given G background. Rapid and slow movements were studied to assess the role of proprioceptive feedback. 3. G level did not affect the amplitude of rapid movements, indicating that subjects were able to plan and to generate appropriate motor commands for the new G loading of the arm. The amplitude of slow movements was affected by G level, indicating that proprioceptive feedback is influenced by G level. 4. The effects of G level were similar for horizontal and vertical movements, indicating that proprioceptive information from supporting structures, such as the shoulder joint and muscles, had a role in allowing generation of the appropriate motor commands. 5. The incidence and size of dynamic overshoots were greater in 0G and for rapid movements. This G-related change in damping suggests a decrease in muscle spindle activity in 0G. A decrease in muscle spindle activity in 0G and an increase in 1.8G are consistent with the results of our prior studies on the tonic vibration reflex, locomotion, and perception of head movement trajectory in varying force backgrounds.

Adult↗
PubMed1992

Tonic vibration reflexes and background force level.

On Earth, the functional stretch reflex is an important component in the maintenance of posture and muscle tone. In parabolic flight experiments, we evaluated whether the functional stretch reflex, as reflected in the tonic vibration reflex, adjusts appropriately for changes in background gravitoinertial force level. Virtually immediate alterations of appropriate sign occurred.

Forearm↗