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Biomedical subjects

M L Lewis

Publications and source records attributed to M L Lewis.

At least 19 recordsLinked to original sources
PubMed2001

Long-term follow-up of unoperated macular holes.

OBJECTIVE: To investigate the anatomic and visual acuity outcomes among patients with unoperated macular holes and at least 5 years of follow-up. DESIGN: Retrospective, noncomparative case series from an institutional practice setting. PARTICIPANTS: All patients with unoperated full-thickness macular holes evaluated at Bascom Palmer Eye Institute between January 1, 1968 and December 31, 1993 and observed for at least 5 years. METHODS: Demographic and clinical data were abstracted from patients' medical records and ophthalmologic photography records. For patients with bilateral macular holes, only one eye was included. MAIN OUTCOME MEASURES: Visual acuity and clinical features on initial examination, at 5 years, and at final follow-up. RESULTS: The study included 65 eyes of 65 patients with a median age of 65 years (range, 52-85 years) and a median follow-up of 9.3 years (range, 5-29 years). On initial examination at Bascom Palmer Eye Institute, the macular hole was stage 2 in 15 eyes (24%), stage 3 in 23 eyes (37%), and stage 4 in 25 eyes (40%). At final follow-up, the macular hole was stage 3 in 10 eyes (16%) and stage 4 in 53 eyes (84%). Visual acuity was 20/200 or worse in 35 eyes (54%) on initial examination, in 43 eyes (74%) at 5 years, and in 53 eyes (82%) at final follow-up. Poorer visual acuity on initial examination was a significant predictor of poorer final vision (P < 0.01). Other accompanying clinical features such as the presence of operculum, posterior vitreous detachment, and epiretinal membrane were not significantly associated with final vision. Throughout follow-up, there was a redistribution and reduced number of yellow nodular opacities at the level of the retinal pigment epithelium at the base of the macular holes and the development of retinal pigment epithelial atrophy around the macular holes. CONCLUSIONS: Long-term follow-up of unoperated macular holes demonstrates progression in hole size and stage, vision loss which generally stabilizes at the 20/200 to 20/400 level, a redistribution and reduced number of yellow nodular opacities at the level of the retinal pigment epithelium, and the development of retinal pigment epithelial atrophy surrounding the macular hole, resulting in a "bull's-eye" macular appearance.

Aged↗
PubMed2001

Effect of vibrational stress and spaceflight on regulation of heat shock proteins hsp70 and hsp27 in human lymphocytes (Jurkat).

Heat shock protein levels are increased in cells as a result of exposure to stress. To determine whether heat shock protein regulation could be used to evaluate stress in cells during spaceflight, the response of Jurkat cells to spaceflight and simulated space shuttle launch vibration was investigated by evaluating hsp70 and hsp27 gene expression. Gene expression was assessed by reverse transcription-polymerase chain reaction using mRNA extracted from vibrated, nonvibrated, space-flown, and ground control cells. Results indicate that mechanical stresses of vibration and low gravity do not up-regulate the mRNA for hsp70, although the gene encoding hsp27 is up-regulated by spaceflight but not by vibration. In ground controls, the mRNA for hsp70 and hsp27 increased with time in culture. We conclude that hsp70 gene expression is a useful indicator of stress related to culture density but is not an indicator of the stresses of launch vibration or microgravity. Up-regulation of hsp27 gene expression in microgravity is a new finding.

Cell Division↗
PubMed2000

Streptococcal toxic shock in a horse.

A 14-year-old horse was admitted to the veterinary hospital for treatment of tachycardia and lethargy. Initial diagnoses were ventricular tachycardia and renal dysfunction. During hospitalization other findings included fever, renal failure, hepatic failure, hypotension, and intermittent ventricular arrhythmias. Bacteriologic culture of 2 blood samples collected during febrile crises 7 days apart yielded Streptococcus mitis. These culture results along with other clinical and physical examination findings fulfill the criteria for a diagnosis of streptococcal toxic shock syndrome, previously described for humans and dogs. To our knowledge this is the first reported instance of this disease in a horse.

Animals↗
PubMed2000

Lumbar interbody fusion using the Brantigan I/F cage for posterior lumbar interbody fusion and the variable pedicle screw placement system: two-year results from a Food and Drug Administration investigational device exemption clinical trial.

STUDY DESIGN: A carbon fiber-reinforced polymer cage implant filled with autologous bone was designed to separate the mechanical and biologic functions of posterior lumbar interbody fusion. OBJECTIVES: To test the safety and efficacy of the carbon cage with pedicle screw fixation in a 2-year prospective study performed at six centers under a protocol approved by the Food and Drug Administration, and to present the data supporting the Food and Drug Administration approved indications. SUMMARY OF BACKGROUND DATA: The success of posterior lumbar interbody fusion has been limited by mechanical and biologic deficiencies of the donor bone. Some failures of pedicle screw fixation may be attributable to the absence of adequate load sharing through the anterior column. Combining an interbody fusion device with pedicle screw fixation may address some limitations of posterior lumbar interbody fusion or pedicle screw fixation in cases that are more complex mechanically. METHODS: This clinical study of posterior lumbar interbody fusion with pedicle screw fixation involved a prospective group of 221 patients. RESULTS: Fusion success was achieved in 176 (98.9%) of 178 patients. In the management of degenerative disc disease in patients with prior failed discectomy surgery, clinical success was achieved in 79 (86%) of 92 patients, and radiographic bony arthrodesis in 91 (100%) of 91 patients. Disc space height, averaging 7.9 mm before surgery, was increased to 12.3 mm at surgery and maintained at 11.7 mm at 2 years. Fusion success was notdiminished over multiple fusion levels. These results were significantly better than those reported in prior literature. Although significant surgical complications occurred, those attributable to the implant devices occurred less frequently and generally were minor. CONCLUSIONS: The Brantigan I/F Cage for posterior lumbar interbody fusion and the Variable Screw Placement System are safe and effective for the management of degenerative disc disease.

Adult↗
PubMed2000

FePer 1, a gene encoding an evolutionarily conserved 1-Cys peroxiredoxin in buckwheat (Fagopyrum esculentum Moench), is expressed in a seed-specific manner and induced during seed germination.

A cDNA corresponding to 1-Cys peroxiredoxin, an evolutionarily conserved thiol-specific antioxidant enzyme, was isolated from buckwheat (Fagopyrum esculentum Moench), a dicotyledonous plant species belonging to the Polygonaceae family. The cDNA, which we have designated as FePer1, contains a major open reading frame capable of encoding a polypeptide of 219 residues with a predicted molecular mass of 24.3kDa. The deduced primary structure of FePer1 polypeptide shows a high level (about 70%) of sequence homology to other recently identified plant 1-Cys peroxiredoxins. FePer1 also exhibits a significant level of sequence similarity to non-plant 1-Cys peroxiredoxins, sharing 52 and 42% identities with mammalian and fungal 1-Cys peroxiredoxins, respectively. As for all 1-Cys peroxiredoxins identified from various organisms, the amino acid sequence proposed to constitute the active site of the enzyme is highly conserved in FePer1 polypeptide. The gene corresponding to FePer1 cDNA is a single-copy gene in the buckwheat genome. Its expression is regulated in a seed-specific and temporal manner during seed development. FePer1 gene is induced transiently for a short period immediately after seed imbibition.

Amino Acid Sequence↗
PubMed2000

Fas/APO-1 protein is increased in spaceflown lymphocytes (Jurkat).

Human lymphocytes flown on the Space Shuttle respond poorly to mitogen stimulation and populations of the lymphoblastoid T cell line, Jurkat, manifest growth arrest, increase in apoptosis and time- and microgravity-dependent increases in the soluble form of the cell death factor, Fas/APO-1 (sFas). The potential role of apoptosis in population dynamics of space-flown lymphocytes has not been investigated previously. We flew Jurkat cells on Space Transportation System (STS)-80 and STS-95 to determine whether apoptosis and the apparent microgravity-related release of sFas are characteristic of lymphocytes in microgravity. The effects of spaceflight and ground-based tests simulating spaceflight experimental conditions, including high cell density and low serum concentration, were assessed. Immunofluorescence microscopy showed increased cell associated Fas in flown cells. Results of STS-80 and STS-95 confirmed increase in apoptosis during spaceflight and the release of sFas as a repeatable, time-dependent and microgravity-related response. Ground-based tests showed that holding cells at 1.5 million/ml in medium containing 2% serum before launch did not increase sFas. Reports of increased Fas in cells of the elderly and the increases in spaceflown cells suggest possible similarities between aging and spaceflight effects on lymphocytes.

Aging↗
PubMed2000

Regulation of heat shock protein message in Jurkat cells cultured under serum-starved and gravity-altered conditions.

Although our understanding of effects of space flight on human physiology has advanced significantly over the past four decades, the potential contribution of stress at the cellular and gene regulation level is not characterized. The objective of this ground-based study was to evaluate stress gene regulation in cells exposed to altered gravity and environmentally suboptimal conditions. We designed primers to detect message for both the constitutive and inducible forms of the heat shock protein, HSP-70. Applying the reverse transcriptase-polymerase chain reaction (RT-PCR), we probed for HSP-70 message in human acute T-cell leukemia cells, Jurkat, subjected to three types of environmental stressors: (1) altered gravity achieved by centrifugation (hypergravity) and randomization of the gravity vector in rotating bioreactors, (2) serum starvation by culture in medium containing 0.05% serum, and (3) temperature elevation (42 degrees C). Temperature elevation, as the positive control, significantly increased HSP-70 message, while centrifugation and culture in rotating bioreactors did not upregulate heat shock gene expression. We found a fourfold increase in heat shock message in serum-starved cells. Message for the housekeeping genes, actin and cyclophilin, were constant and comparable to unstressed controls for all treatments. We conclude that gravitational perturbations incurred by centrifugal forces, exceeding those characteristic of a Space Shuttle launch (3g), and culture in rotating bioreactors do not upregulate HSP-70 gene expression. In addition, we found RT-PCR useful for evaluating stress in cultured cells.

Aerospace Medicine↗
PubMed2000

The effects of intense physical exercise on secondary antibody response in young and old mice.

BACKGROUND AND PURPOSE: Based largely on data from young subjects, intense physical exercise is believed to suppress immune function. In addition, immune function, including secondary antibody response, declines with advancing age. Therefore, intense exercise in old subjects may further suppress the secondary antibody response. The purpose of this in vivo study was to investigate the effects of intense physical exercise on secondary antibody response in young (6-8 weeks) and old (22-24 months) C57BL/6 mice. SUBJECTS AND METHODS: Data were obtained from 22 young and 18 old C57BL/6 mice that were immunized to human serum albumin (HSA) and randomly divided into 3 groups. Two groups were exposed to a single bout of intense exercise to exhaustion and immediately boosted with an injection of HSA. The first group did not exercise further, but the second group continued with daily bouts of intense exercise to exhaustion for 9 days. The third group (control group) did not undergo intense exercise, but received the booster injection of HSA at the same time as the other groups. Ten days after the HSA booster injection, when high level of antibodies are produced in secondary antibody response, serum anti-HSA antibodies were measured by enzyme-linked immunosorbent assay. RESULTS: Young mice did not show suppression of secondary antibody response following intense exercise. However, old mice, exposed to a single bout of intense exercise, had an enhanced response similar to the response seen in young control mice. CONCLUSION AND DISCUSSION: The widely accepted hypothesis of immunosuppression resulting from intense exercise may not be true for old mice.

Aging↗
PubMed1999

Visual acuity outcomes of patients 50 years of age and older with high myopia and untreated choroidal neovascularization.

OBJECTIVE: To evaluate visual outcomes of untreated submacular choroidal neovascularization (CNV) in patients 50 years of age and older with high myopia. DESIGN: Retrospective observational case series. PARTICIPANTS: Twenty-two eyes in 22 patients were studied. All were 50 years of age and older with myopia of 6.0 diopters (D) or greater or an axial length of 25.5 mm or greater. Patients had untreated CNV documented by clinical examination and fluorescein angiography at two medical centers between 1986 and 1997. INTERVENTION: Demographic and clinical data were abstracted from patients' medical records. MAIN OUTCOME MEASURE: Visual acuity at 1 year after CNV diagnosis. RESULTS: The study included 22 eyes of 22 patients (mean age, 63.1 years; mean refraction, -11.0 D). Baseline visual acuity (VA) in the study eye was 20/40 or greater in 2 (9%) patients, 20/50 to 20/150 in 9 (41%) patients, and 20/200 or less in 11 (50%) patients. Drusen were present in seven (32%) eyes, and lacquer cracks were noted in ten (45%) eyes. Mean refractive error was -7.0 D for patients with drusen and -12.5 D for patients without drusen. Choroidal neovascularization was less than 0.25 disc diameters (DD) in 11 (50%) eyes, 0.25 to 0.5 DD in 5 (23%) eyes, and greater than 0.5 DD in 6 (27%) eyes. Visual acuity in the study eye 1 year after CNV diagnosis was 20/40 or greater in 3 (14%) patients, 20/50 to 20/150 in 3 (14%) patients, and 20/200 or less in 16 (73%) eyes. The presence of drusen was significantly associated with older age and a lower degree of myopia but was not associated with size of the CNV or visual acuity outcome. CONCLUSION: When compared to patients younger than 50 years of age with high myopia and CNV reported in previous publications, the patients in the current series generally have poorer visual outcomes.

Aged↗
PubMed1999

Hair combing interactions: a new paradigm for research with African-American mothers.

The hair combing interaction is proposed as a naturalistic observational research paradigm, within the conceptual framework of attachment theory, for understanding the socioemotional domains of African-American mother-child relationships. A pilot study of 11 mother-daughter dyads explores the validity of the hair combing context for assessing strategies of racial and gender socialization of children, evolving mother-child relationships, and the formation of internal working models of attachment relationships. The model is discussed as a method for research into enduring qualities of the mother-child relationship.

Adolescent↗
PubMed1999

The kinetics of translocation and cellular quantity of protein kinase C in human leukocytes are modified during spaceflight.

Protein kinase C (PKC) is a family of serine/threonine kinases that play an important role in mediating intracellular signal transduction in eukaryotes. U937 cells were exposed to microgravity during a space shuttle flight and stimulated with a radiolabeled phorbol ester ([3H]PDBu) to both specifically label and activate translocation of PKC from the cytosol to the particulate fraction of the cell. Although significant translocation of PKC occurred at all g levels, the kinetics of translocation in flight were significantly different from those on the ground. In addition, the total quantity of [3H]PDBu binding PKC was increased in flight compared to cells at 1 g on the ground, whereas the quantity in hypergravity (1.4 g) was decreased with respect to 1 g. Similarly, in purified human peripheral blood T cells the quantity of PKCdelta varied in inverse proportion to the g level for some experimental treatments. In addition to these novel findings, the results confirm earlier studies which showed that PKC is sensitive to changes in gravitational acceleration. The mechanisms of cellular gravisensitivity are poorly understood but the demonstrated sensitivity of PKC to this stimulus provides us with a useful means of measuring the effect of altered gravity levels on early cell activation events.

Biological Transport↗
PubMed1999

Women's approaches to decision making about mammography.

Health professionals have an obligation to understand women's decision making about mammography and to advocate for their active participation in health care decision making. Although mammography is a major screening measure for the second largest cancer killer of women, only approximately half of women older than age 50 years, and fewer older than age 70 years, undergo mammography in accordance with American Cancer Society (ACS) guidelines. Therefore, the purpose of this study was to identify women's overall decision-making approaches when considering mammography. Subjects were a purposive, convenience sample of 50 women in the community who had made a decision about mammography; they included those who chose to have mammograms and those who decided not to have mammograms according to the pre-1997 ACS guidelines. Subjects participated in audiotaped interviews. Results indicated that women approached the mammography decision differently, regardless of the decision they made. Three overall decision-making approaches to addressing risk factors, issues about mammography, or other factors before their decision were evident. The approaches were (1) thoughtful consideration; (2) cursory consideration; and (3) little or no consideration. Each approach has implications for nurses who assist women in making decisions about mammography.

Adult↗
PubMed1999

Violence against nurses in outpatient mental health settings.

Nurses in outpatient mental health settings who have been assaulted may have an increased sense of vulnerability. Assault and verbal threats influence how nurses view client behavior. Mechanisms need to be developed to protect staff in outpatient settings and to support colleagues when assaults or threats occur.

Adult↗
PubMed1999

Cognitive behavioral group therapy for residents in assisted-living facilities.

Geriatric depression is a disabling illness that is associated with increased morbidity and mortality and deserves aggressive and early intervention. Cognitive-behavioral group therapy is an effective intervention for the treatment of geriatric depression and can be used with residents in an assisted living facility to manage and prevent depression. Cognitive-behavioral group therapy protocol modifications for residents in assisted-living facilities aids their participation and learning.

Aged↗
PubMed1998

Use of an adaptable cell culture kit for performing lymphocyte and monocyte cell cultures in microgravity.

The results of experiments performed in recent years on board facilities such as the Space Shuttle/Spacelab have demonstrated that many cell systems, ranging from simple bacteria to mammalian cells, are sensitive to the microgravity environment, suggesting gravity affects fundamental cellular processes. However, performing well-controlled experiments aboard spacecraft offers unique challenges to the cell biologist. Although systems such as the European 'Biorack' provide generic experiment facilities including an incubator, on-board 1-g reference centrifuge, and contained area for manipulations, the experimenter must still establish a system for performing cell culture experiments that is compatible with the constraints of spaceflight. Two different cell culture kits developed by the French Space Agency, CNES, were recently used to perform a series of experiments during four flights of the 'Biorack' facility aboard the Space Shuttle. The first unit, Generic Cell Activation Kit 1 (GCAK-1), contains six separate culture units per cassette, each consisting of a culture chamber, activator chamber, filtration system (permitting separation of cells from supernatant in-flight), injection port, and supernatant collection chamber. The second unit (GCAK-2) also contains six separate culture units, including a culture, activator, and fixation chambers. Both hardware units permit relatively complex cell culture manipulations without extensive use of spacecraft resources (crew time, volume, mass, power), or the need for excessive safety measures. Possible operations include stimulation of cultures with activators, separation of cells from supernatant, fixation/lysis, manipulation of radiolabelled reagents, and medium exchange. Investigations performed aboard the Space Shuttle in six different experiments used Jurkat, purified T-cells or U937 cells, the results of which are reported separately. We report here the behaviour of Jurkat and U937 cells in the GCAK hardware in ground-based investigations simulating the conditions expected in the flight experiment. Several parameters including cell concentration, time between cell loading and activation, and storage temperature on cell survival were examined to characterise cell response and optimise the experiments to be flown aboard the Space Shuttle. Results indicate that the objectives of the experiments could be met with delays up to 5 days between cell loading into the hardware and initial in flight experiment activation, without the need for medium exchange. Experiment hardware of this kind, which is adaptable to a wide range of cell types and can be easily interfaced to different spacecraft facilities, offers the possibility for a wide range of experimenters successfully and easily to utilise future flight opportunities.

Biological Transport↗
PubMed1998

Challenges of teaching graduate psychiatric-mental health nursing with distance education technologies.

As student demographics change and distance educational technology continues to evolve, faculty teaching advanced psychiatric-mental health nursing are attempting to meet the needs of students at distant sites through telecommunications. Graduate education in psychiatric-mental health nursing at the University of Minnesota School of Nursing has used distance education technology since 1994. The use of technology, such as interactive television, audio and audio/video telephone conferencing, facsimile, and electronic mail to teach has been exciting and challenging. This article discusses challenges related to connectedness, confidentiality, and communication; describes approaches to address these challenges; and identifies student, faculty, and environmental attributes that help make teaching with this technology successful.

Education, Nursing, Graduate↗
PubMed1998

Spaceflight alters microtubules and increases apoptosis in human lymphocytes (Jurkat).

Alteration in cytoskeletal organization appears to underlie mechanisms of gravity sensitivity in space-flown cells. Human T lymphoblastoid cells (Jurkat) were flown on the Space Shuttle to test the hypothesis that growth responsiveness is associated with microtubule anomalies and mediated by apoptosis. Cell growth was stimulated in microgravity by increasing serum concentration. After 4 and 48 h, cells filtered from medium were fixed with formalin. Post-flight, confocal microscopy revealed diffuse, shortened microtubules extending from poorly defined microtubule organizing centers (MTOCs). In comparable ground controls, discrete microtubule filaments radiated from organized MTOCs and branched toward the cell membrane. At 4 h, 30% of flown, compared to 17% of ground, cells showed DNA condensation characteristic of apoptosis. Time-dependent increase of the apoptosis-associated Fas/ APO-1 protein in static flown, but not the in-flight 1 g centrifuged or ground controls, confirmed microgravity-associated apoptosis. By 48 h, ground cultures had increased by 40%. Flown populations did not increase, though some cells were cycling and actively metabolizing glucose. We conclude that cytoskeletal alteration, growth retardation, and metabolic changes in space-flown lymphocytes are concomitant with increased apoptosis and time-dependent elevation of Fas/APO-1 protein. We suggest that reduced growth response in lymphocytes during spaceflight is linked to apoptosis.

Apoptosis↗