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Biomedical subjects

K Allen

Publications and source records attributed to K Allen.

At least 55 records · Page 3Linked to original sources
PubMed1998

Structural and functional changes in proteins induced by free radical-mediated oxidative stress and protective action of the antioxidants N-tert-butyl-alpha-phenylnitrone and vitamin E.

The free radical theory of aging proposes that reactive oxygen species (ROS) cause oxidative damage over the lifetime of the subject. It is the cumulative and potentially increasing amount of accumulated damage that accounts for the dysfunctions and pathologies seen in normal aging. We have previously demonstrated that both normal rodent brain aging and normal human brain aging are associated with an increase in oxidative modification of proteins and in changes in plasma membrane lipids. Several lines of investigation indicate that one of the likely sources of ROS is the mitochondria. There is an increase in oxidative damage to the mitochondrial genome in aging and a decreased expression of mitochondrial mRNA in aging. We have used a multidisciplinary approach to the characterization of the changes that occur in aging and in the modeling of brain aging, both in vitro and in vivo. Exposure of rodents to acute normobaric hyperoxia for up to 24 h results in oxidative modifications in cytosolic proteins and loss of activity for the oxidation-sensitive enzymes glutamine synthetase and creatine kinase. Cytoskeletal protein spin labeling also reveals synaptosomal membrane protein oxidation following hyperoxia. These changes are similar to the changes seen in senescent brains, compared to young adult controls. The antioxidant spin-trapping compound N-tert-butyl-alpha-phenylnitrone (PBN) was effective in preventing all of these changes. In a related study, we characterized the changes in brain protein spin labeling and cytosolic enzyme activity in a series of phenotypically selected senescence-accelerated mice (SAMP), compared to a resistant line (SAMR1) that was derived from the same original parents. In general, the SAM mice demonstrated greater oxidative changes in brain proteins. In a sequel study, a group of mice from the SAMP8-sensitive line were compared to the SAMR1-resistant mice following 14 days of daily PBN treatment at a dose of 30 mg/kg. PBN treatment resulted in an improvement in the cytoskeletal protein labeling toward that of the normal control line (SAMR1). The results of these and related studies indicate that the changes in brain function seen in several different studies may be related to the progressive oxidation of critical brain proteins and lipids. These components may be critical targets for the beneficial effects of gerontotherapeutics both in normal aging and in disease of aging.

Adult↗
PubMed1998

Biosynthesis of endotubin: an apical early endosomal glycoprotein from developing rat intestinal epithelial cells.

Endosomes are the site of sorting of internalized receptors and ligands in all cell types and, in polarized cells, the apical endosomal compartment is involved in the selective transepithelial transport of immunoglobulins and growth factors. The biochemical composition of this specialized compartment remains largely unresolved. We have characterized a glycoprotein, called endotubin, that is located in the apical endosomal tubules of developing rat intestinal epithelial cells. A monoclonal antibody against endotubin recognizes a broad band of 55-60kDa, which upon isoelectric focusing can be resolved into two bands, and a faint band of 140kDa. Metabolic labelling followed by immunoprecipitation indicates that endotubin is synthesized as a 140kDa precursor that is cleaved to the 55-60kDa forms. High pH washing of endosomal membranes removes the 55-60kDa forms from the membrane, whereas the high-molecular-mass form remains membrane associated and appears to be an integral membrane protein. Immunoblotting with a polyclonal antibody against the putative cytoplasmic tail of the protein identifies a 140kDa band and a band of 74kDa, presumably the cleavage product. Immunoprecipitation with antibodies against the 55-60kDa form results in coprecipitation of a 74kDa protein, and immunoprecipitation with antibody against the 74kDa protein results in coprecipitation of the 55-60kDa form. Epitope mapping of the monoclonal antibody binding site supports a proposed type I membrane protein orientation. We propose that endotubin is proteolytically processed into a heterodimer with the 55-60kDa fragment remaining membrane-associated through a non-covalent association with the membrane-bound 74kDa portion of the molecule.

Animals↗
PubMed1998

Conceptualizing sexual health in cancer care.

This qualitative study was designed to describe women's experiences with changes in sexual function related to physical comfort, sexual satisfaction, and feelings of intimacy post-treatment for gynecological cancer. The 17 women who participated in this study described sexuality as a much broader construct. Contrary to existing literature, sexual functioning was found to be one aspect that contributed to the view of the self as a sexual being, but the women's perceptions were not limited to this single dimension. The identification of multidimensional components to be considered in developing a conceptual model to describe sexual health are presented. This study indicates that sexuality should be viewed as a health issue that has an impact on quality of life.

Adult↗
PubMed1998

Essential concepts of addiction for general nursing practice.

Nurses face the challenge of providing care to persons who use, abuse, or become addicted to alcohol, tobacco, and other drugs in all health care settings-those specific to cure as well as those specific to prevention. The opportunity to address the problem with their clients presents itself to nurses practicing along the full continuum of care. This article addresses basic concepts for general nursing practice.

Communication↗
PubMed1998

Preventing and managing childhood emergencies in schools.

The Emergency Medical Services for Children (EMSC) program, initially funded in 1984, is jointly administered by the Health Resources and Services Administration and the National Highway Traffic Administration. The program is designed to reduce child and youth mortality and morbidity resulting from severe illness or trauma. Several initiatives, focused at the federal, state, and local levels, have established collaboration between the education and health communities. They include injury prevention education and programs in school settings; school and staff preparation for a medical emergency; and emergency care planning for school children with special health care needs. This article provides an overview of key issues.

Child↗
PubMed1997

Diagnostic and therapeutic video assisted thoracic surgery (VATS) following chest trauma.

OBJECTIVE: Thoracic injury remains a major source of morbidity and mortality in urban trauma centers. With the advent and increasing expertise in video assisted thoracic surgery, this modality has become an attractive alternative in the management of patients with thoracic injury. This report will review our experience with video assisted thoracic surgery at a level I trauma center and attempt to further delineate the indications for and timing of thoracoscopy in thoracic trauma. METHODS: We identified 16 patients who had undergone video assisted thoracic surgery following chest trauma between July 1991 and June 1994. There were 15 penetrating and one blunt trauma. All 16 patients were initially treated with tube thoracostomy. From 0-20 days post-injury, video assisted thoracic surgery was attempted with either diagnostic or therapeutic intentions. RESULTS: Twelve of the 16 patients (75%) had successful thoracoscopy. Three patients had diaphragmatic injury excluded and nine patients had successful evacuation of clotted hemothoraces. Evacuation of clotted hemothorax up to 7 days post-injury was safe and easily accomplished. Four patients (25%) had unsuccessful thoracoscopy and were converted to standard thoracotomy; failure was attributed to either suboptimal single lung ventilation or severe pleural inflammatory reaction. The only death in the entire group occurred 10 days after a thoracotomy for retained hemothorax. The median post-operative hospital stay following successful video assisted thoracic surgery was 3.5 days. CONCLUSIONS: Video assisted thoracic surgery can be utilized as an effective and safe method for the initial diagnostic evaluation and surgical management of stable patients with penetrating thoracic trauma.

Adolescent↗
PubMed1997

Weight gain associated with adjuvant tamoxifen therapy in stage I and II breast cancer: fact or artifact?

There is a perception that tamoxifen causes weight gain in breast cancer patients. The purpose of this research study was to determine if weight gain is associated with tamoxifen therapy and to observe the impact of weight gain on recurrence and survival. Prognostic indicators, changes in weight, and disease status from diagnosis to the end of treatment were studied in 200 consecutive Stage I and II breast cancer patients, not receiving systemic chemotherapy, admitted from 1986 to the present, with observation periods ranging from 3-5 years. A mean weight gain of 1.2 Kgs was seen in all patients; however, weight gain was not significantly different for those receiving tamoxifen vs. those not receiving tamoxifen, (P = 0.66, CI 95% for the difference -1.8 Kgs to +1.2 Kgs). Weight gain during treatment with tamoxifen was not correlated with treatment duration or with recurrence or survival. Age at diagnosis was positively correlated to weight gain in all groups. Our data failed to show that tamoxifen is associated with weight gain. The moderate weight gain observed in this patient population is comparable to the general aging disease-free population and may no be treatment-related. These findings may help to alleviate some concerns of both physicians and patients when tamoxifen is the drug of choice for adjuvant therapy.

Adult↗
PubMed1997

Social indicators and the prediction of psychiatric admission in different diagnostic groups.

BACKGROUND: Recent findings indicate that the established association between social indicators of deprivation and psychiatric admission rates may not hold across all diagnoses. METHOD: Admission rates in individuals aged 16-64 years for 71 electoral wards in North Staffordshire were calculated for six diagnostic groups using data from the Korner Episode System for 1987-1993. These were correlated with selected individual census variables, Townsend and Jarman indices. The ability of regression models to predict admission rates was tested. RESULTS: The strongest correlations were found for total admissions (r 0.44-0.79). Strong correlations were found for neurotic disorders/depression (r 0.29-0.62), schizophrenia (r 0.24-0.59), all non-psychotic disorders combined (r 0.41-0.71) and all psychotic disorders combined (r 0.33-0.67). Predicted admission rates for total admissions, psychotic and non-psychotic admissions using regression models showed strong positive correlations with observed admission rates. CONCLUSIONS: The strong correlations between social indicators of deprivation and total psychotic admission rates are consistent with the results of previous studies. The strong associations between social indicators and admissions for non-psychotic disorders is contrary to previous findings and may be partly explained by the relatively high admission rates for neurotic disorders.

Adolescent↗
PubMed1997

Reproducibility of bone height measurements made on serial radiographs.

The objective of this study was to determine the reproducibility of alveolar bone height measurements made on digitized images of serial radiographs using 3 different alignment systems for taking serial radiographs: 1) XCP Rinn System, 2) XCP Rinn System modified to include an alignment pin, and 3) I/EGAD system (impression based-electronically guided alignment device). Eighty duplicate films taken 1 hour apart of randomly selected anterior or posterior sites for alignment systems 1 and 2 were taken on 40 subjects. Thirty-eight duplicate films were taken of posterior and anterior sites on 19 subjects with alignment system 3. Cemento-enamel junction alveolar crest measurements were made on digital images using the side-by-side technique. Image pairs of serial radiographs were dichotomized into well-matched and poorly matched groups based on subjective evaluation of the geometric likeness. Of those taken with system 1, 47% were well matched; with system 2, 62%; and with system 3, 98%. The measurement error of change in radiographic bone height, defined as twice the standard deviation of difference (mm), was determined. This varied between 1.03 mm for poorly matched radiographic pairs taken with alignment system 1 and 0.52 mm for all radiographic pairs taken with alignment system 3. These results can be used together with power calculations to select an alignment system for a particular study. For example, power calculations indicate that detecting a bone change of 0.5 mm using the I/EGAD system would require one-third of the subjects needed when using the XCP Rinn method.

Adult↗
PubMed1996

The value of service dogs for people with severe ambulatory disabilities. A randomized controlled trial.

OBJECTIVE: To assess the value of service dogs for people with ambulatory disabilities. DESIGN: Randomized, controlled clinical trial. SETTING: Environments of study participants. PARTICIPANTS: Forty-eight individuals with severe and chronic ambulatory disabilities requiring use of wheelchairs who were recruited from advocacy and support groups for persons with muscular dystrophy, multiple sclerosis, traumatic brain injury, and spinal cord injury. Participants were matched on age, sex, marital status, race, and the nature and severity of the disability in order to create 24 pairs. Within each pair, participants were randomly assigned to either the experimental group or a wait-list control group. INTERVENTION: Experimental group members received trained service dogs 1 month after the study began, and subjects in the wait-list control group received dogs in month 13 of the study. MAIN OUTCOME MEASURES: Dependent variables evaluated were self-reported assessments of psychological well-being, internal locus of control, community integration, school attendance, part-time work status, self-esteem, marital status, living arrangements, and number of biweekly paid and unpaid assistance hours. Data collection occurred every 6 months over a 2-year period, resulting in five data collection points for all subjects. RESULTS: Significant positive changes in all but two dependent measures were associated with the presence of a service dog both between and within groups (P<.001). Psychologically, all participants showed substantial improvements in self-esteem, internal locus of control, and psychological well-being within 6 months after receiving their service dog. Socially, all participants showed similar improvements in community integration. Demographically, all participants showed increases in school attendance and/or part-time employment. Economically, all participants showed dramatic decreases in the number of both paid and unpaid assistance hours. CONCLUSIONS: Trained service dogs can be highly beneficial and potentially cost-effective components of independent living for people with physical disabilities.

Activities of Daily Living↗
PubMed1996

Validation of quantitative digital subtraction radiography using the electronically guided alignment device/impression technique.

The electronically guided alignment device (EGAD) has been demonstrated to function well with a custom fabricated stent for taking radiographs for subtraction. The objective of this study is to demonstrate that this device functions well when used with an impression bite-block rather than a full arch acrylic stent. Nineteen subjects participated. Two vinyl siloxane impressions were made for each subject and a pair of x-rays was taken with each impression. The location for study was divided among 7 for the maxillary premolar-1st molar region, 6 for the mandibular premolar-1st molar region, and 6 for the incisor-canine region. To simulate bone change 3 bone chips (approximately 1, 7, and 10 mg) were positioned in the mucobuccal fold when one of each pair of x-rays was taken. Pairs of radiographs were subtracted and the bone change (chips) isolated by thresholding to determine their area. An aluminum ramp was used to determine volume. A strong linear relationship between actual chip weight and equivalent aluminum volume (r2 = 0.64, P < 0.001) was obtained for all regions of the mouth when considered together. The strongest relationship of the 3 regions was for mandibular premolar-1st molar sites, r2 = 0.78. These data indicate that the EGAD/impression technique is suitable for taking radiographs in all areas of the mouth for quantitative digital subtraction.

Adult↗