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Biomedical subjects

L A Davis

Publications and source records attributed to L A Davis.

At least 19 recordsLinked to original sources
PubMed1998

Precollege enrichment programs intended to increase the representation of minorities in medicine.

The authors reviewed the literature published from 1966 to 1996 to identify enrichment programs for underrepresented minority precollege students sponsored by medical schools and affiliated programs, finding 19 articles describing 27 programs. The authors categorized the reported programs according to the components they contained. Most programs contained more than one component type. Twenty-four programs had an academic enhancement component. Two thirds had a motivational component to encourage students to consider medical and other health careers. Two programs set up mentoring relationship between students and health professionals. There were four research apprenticeships and three academic partnerships between medical schools and local school districts. Twelve of the 27 programs were evaluated in the literature. Eight evaluations focused on identifying the numbers of students who continued their education into college and professional schools. Five programs reported participant satisfaction or identified other short-term outcomes such as gains on standardized tests. While the percentage of participants completing college and entering health care careers is impressive, the authors do not believe that the educational success of participants can be attributed to involvement in these programs. The authors recommend ways to improve the quality and interpretability of enrichment program evaluations. Evaluators should adopt common terminology for activities and outcomes. Participants' economic and educational disadvantages should be described. Programs' theoretical underpinnings should be identified and related to evaluation. Measures should include immediate effects as well as long-term outcomes. Where possible, data from comparison groups should be reported to support conclusions. Adequate funding needs to be available to design and complete reasonable evaluations.

Education, Medical↗
PubMed1998

Enrichment programs for undergraduate college students intended to increase the representation of minorities in medicine.

The authors reviewed the literature published from 1966 to 1996 to identify enrichment programs for underrepresented minority college students sponsored by medical schools and affiliated programs, finding 20 such programs. The programs reported in the literature underestimate the number and variety of programs known to exist by about two thirds. The authors categorized the reported programs according to the types of components they contained. Most programs contained more than one component type. Eighteen of the programs had an academic enrichment component. Thirteen programs included components focused on preparation for the admission process. Mentoring activities were a component of only four of the programs. Eighteen of the 20 programs were evaluated in the literature. The largest focus of evaluation activities was the success of program participants entering medical school. While the medical school matriculation rate was quite high, these results were difficult to interpret as the studies did not use control groups. The evaluations could not demonstrate, therefore, that the programs were responsible for increased admission of minorities to medical schools. Relatively few studies measured the immediate effects of the programs' efforts. Further, there was even less evidence of which program components in particular were effective. A more public and energetic discussion of these programs in the medical education literature is essential. In a political and social environment that calls for accountability, programs must be able to clearly and truthfully declare what they have accomplished. Without this type of public discussion, enrichment programs for underrepresented minorities may continue to appear to be worthwhile endeavors, but lacking solid support and foundation and vulnerable to losing funding.

Counseling↗
PubMed1997

Comparison of detergent and protease enzyme combinations for the detection of scrapie-associated fibrils from the central nervous system of sheep naturally affected with scrapie.

Standardized samples of tissue from the central nervous system of four sheep naturally affected with scrapie and from four healthy control sheep were subjected to a centrifugal extraction technique used to obtain scrapie-associated fibrils; the latter were then demonstrated by negative-contrast transmission electron microscopy. This regime was used to evaluate the fibril yield obtained from the 25 possible combinations of five different detergents and five different proteolytic enzymes. N-lauroylsarcosine detergent was found to be the most efficient detergent for all five enzymes, followed by sulphabetaine 3-14. Sodium dodecyl sulphate detergent was successful only in combination with a subtilisin Carlsberg enzyme. Octylglucoside and nonidet P40 detergents did not produce fibrils with any of the enzymes. Proteinase K was the least efficient of the five enzymes when used in combination with N-lauroylsarcosine; subtilisin Carlsberg, clostripain, pronase and trypsin enzymes all gave higher fibril yields. A combination of N-lauroylsarcosine detergent and subtilisin Carlsberg proteolytic enzyme gave the highest fibril yield.

Animals↗
PubMed1997

Nucleus 22 cochlear implantation results in postmeningitic deafness.

Cochlear implant surgery was performed on 13 patients with postmeningitic deafness (seven adults, six children). Two adults and two children (30.8%) had severe labyrinthitis ossificans requiring radical "drill-out." Five of 13 (38.5%) had some bone growth requiring partial drill-out, and four of 13 (30.8%) had normal insertion with no drill-out. Hearing results for patients with no bone growth were similar to nonmeningitic patients; three of four (75%) had open-set speech recognition. Performance of patients with total drill-out was poor; "auditory only" performance was limited to detection and pattern perception of speech, and no patients had open-set speech recognition. Results for patients with partial drill-out were similar to results in patients with no bone growth. Labyrinthitis ossificans not only presents surgical challenges to cochlear implantation but may also adversely affect hearing outcome.

Adolescent↗
PubMed1996

Factors predicting employment 1 year after traumatic spine fracture.

STUDY DESIGN: This prospective cohort study evaluates the employment status of 489 persons after traumatic spine fracture. OBJECTIVES: To determine the rate, type, and predictors of employment 1 year after traumatic spine fracture. SUMMARY OF BACKGROUND DATA: The limited existing literature regarding employment after spine fracture reports variable return-to-work rates, tends to be retrospective, and generally evaluates a limited number of predictor factors at a time. METHODS: Four hundred eighty-nine persons ranging in age from 15 to 64 years who had experienced a spine fracture were assessed by a single examiner at hospital discharge and 1 year postinjury. Employment status and type. discharge neural and functional status, pain level, demographics, injury level and severity, and early treatment details were evaluated. RESULTS: At 1 year postinjury, 54% of subjects were working. A higher percentage of the employed were working part time and for fewer weeks per year than preinjury. A higher percentage were working at unskilled clerical, sales, or service jobs than preinjury. The significant positive (+) and negative (-) predictors of employment were (from strongest to weakest); worked in year previous to injury (+); employed at time of injury (+); Worker's compensation Board coverage (-); spinal fracture surgery (+); high-level spine fracture (-); pain (-); Functional Independence Measure score (+); and days of stay in intensive care unit and spinal unit (-). CONCLUSIONS: For the first year after spinal fracture, unemployment is common. Those who do return to work are more likely to modify the amount and type of work they do and to have been employed preinjury.

Adolescent↗
PubMed1996

Preference for and performance with damped and undamped hearing aids by listeners with sensorineural hearing loss.

This study investigated the relationship between acoustic damping of hearing aid responses and listeners' speech discrimination and judgments of preference and sound quality. Eighteen subjects with essentially equivalent hearing impairments participated. Subjects' speech discrimination was evaluated for a male talker in quiet and in noise and for a female talker in the same conditions with hearing aids with 0 dB, -5 dB, and -10 dB of damping. Subjects also compared the damping levels using eight bipolar adjective pairs and provided judgments of overall preference. Measurements of the hearing aid responses were made in a 2-cm3 coupler and in the subjects' ears using probe microphone techniques. Smoothness of the responses was quantified using the Index of Response Irregularity (IRI) and the Frequency Response Smoothness Quantification Index (FReSQI). Subjects preferred the two damped hearing aid responses to the undamped. They also had better speech discrimination with damped hearing aid responses. The bipolar adjectives were of limited use in comparing hearing aids. A few questions about hearing aid sound quality and preference appear adequate for evaluating listeners' choice of hearing aids. Smoothness of the hearing aid responses in the test box was higher for the damped hearing aids than for the undamped. However, for real ear responses measured using a probe microphone, smoothness did not change as a function of damping level.

Acoustics↗
PubMed1996

Healthy People 2000 Goal 1.12: primary care physicians and exercise counseling.

The Healthy People 2000 Goal 1.12 was designed to increase to 50% the number of primary care physicians who regularly counsel their patients concerning the appropriate frequency, duration, type and intensity of exercise. To assess the overall progress in relation to this goal, a survey of 212 physicians was conducted in an eight county region of northern Mississippi. Fifty-nine physicians completed and returned the survey. The findings indicate that 90% of the physicians perceive exercise to be important and that they are discussing exercise with approximately 50% of their patients aged 40 and older. However, the average length of the counseling segment is two minutes or less. It is therefore probable that the appropriate frequency, duration, type and intensity of exercise may not be adequately discussed during physician-based exercise counseling.

Adult↗
PubMed1994

Acceptance of moderate drinking by alcohol treatment services in the United States.

This study was designed to survey the acceptance of moderate drinking as an outcome goal by alcohol treatment services in the United States. Of a sample of 330 randomly selected services, there were 312 potential respondents of whom 196 (63%) returned surveys that were usable. Three-quarters of respondents reported that nonabstinence was not an acceptable outcome goal for patients in their program; however, 17% of these respondents endorsed the statement that nonabstinence was acceptable for patients in other alcohol programs or for their own patients after discharge. Of the remaining one-quarter of respondents who found moderate drinking acceptable for their patients, 80% worked in outpatient programs and 70% reported moderate drinking as appropriate for only 1-25% of their clientele. Respondents endorsing moderate drinking rated the following factors as important when selecting outcome goals: severity of physiological dependence, drinking history, psychological dependence, previous treatment, criminal behavior and liver function test results.

Adolescent↗
PubMed1993

Pulmonary embolism: early recognition and management in the postanesthesia care unit.

Based on the content of this article, the reader should be able to (1) list patients who are at risk to develop pulmonary embolism; (2) identify measures to prevent pulmonary embolism; (3) list the signs and symptoms of pulmonary embolism; (4) identify diagnostic tests and pertinent findings for pulmonary embolism; (5) identify nursing priorities for a patient with pulmonary embolus; and (6) identify medical and surgical interventions to treat the patient with a pulmonary embolus.

Humans↗
PubMed1993

Electrical systems for improving locomotion after incomplete spinal cord injury: an assessment.

Simple systems for electrical stimulation (1-4 channels) with either surface, percutaneous, or implanted electrodes during locomotion were assessed in 10 subjects who had chronic, incomplete spinal cord injury (SCI). On average, the speed of locomotion was increased by 4 m/min independently of the subject's speed of locomotion without stimulation (0-50 m/min) while oxygen consumption was reduced somewhat. These simple systems can provide practical help, particularly for incomplete SCI subjects who can stand but are lacking or have very limited ability to walk. Further improvement in locomotion requires stabilization and reduction in the duration of the stance phase of locomotion.

Adult↗
PubMed1993

Incomplete neural deficits in thoracolumbar and lumbar spine fractures. Reliability of Frankel and Sunnybrook scales.

Because neural status is used both as a treatment determiner and outcome measure, a universal, reliable scale is required. Experienced personnel, provided with concise definitions, demonstrated high inter-rater reliability of Frankel and Sunnybrook scales (Pearson correlation coefficients 0.71-0.91), with 94-100% intra-rater agreement. Both scales correspond to total sensory and motor function but are insensitive to walking and bladder function. Frankel's wide clinical use, reliability, and simplicity identify it to be the preferred measurement system until a better alternative is developed. Discussion of neural status must include description of bladder and walking function.

Adolescent↗
PubMed1992

Antibodies to beta 1-integrins cause alterations of aortic vasculogenesis, in vivo.

Vasculogenesis is the de novo formation of blood vessels from mesoderm. This process occurs very early in development and provides a convenient system for studying morphogenesis in higher vertebrates. The cell-extracellular matrix (ECM) interactions that occur during dorsal aortic vasculogenesis were examined using the monoclonal antibody, CSAT, a reagent known to neutralize the ligand-binding activity of avian beta 1-integrins. We injected CSAT into quail embryos during a period of active vasculogenesis (4-10 somites). The CSAT antibodies, but not controls, had a marked and reproducible effect on aortic vessel formation. Vasculogenesis appeared to be arrested at the stage when slender cord-like assemblies of angioblasts rearrange to form tubules. Indeed, aortic primordia near the site of CSAT injection did not form patent vessels.

Animals↗
PubMed1992

Perturbation of beta 1 integrin-mediated adhesions results in altered somite cell shape and behavior.

Cell contact and adhesion between somites and the axial extracellular matrix (ECM) is likely to play a fundamental role in vertebrate development. In a preliminary report we showed that injection of the monoclonal antibody CSAT, which recognizes the avian beta 1 integrins, causes a lateral separation of both somites and segmental plate tissue from the embryonic axis (Drake and Little, 1991). In this study we addressed the cell biological response to CSAT injection, particularly the cell-ECM interactions involved in maintaining normal somite-axial relationships. A total of 150 stage 7-10 quail embryos have been injected with CSAT and then cultured for varying periods (1-30 hr). CSAT caused somitic cells to behave abnormally. Changes include, rounding-up, extensive blebbing, and formation of retraction fibers. A majority of separated somites were able to assume normal axial position with further time culture. Whether a somite subsequently aligned at the axis was dependent on the amount of CSAT injected and the postinjection culture period. Embryos in which somites remained separated from the axis after relatively long culture intervals (18-24 hr) displayed abnormal sclerotomal cell migrations. In no case did control injected embryos exhibit cellular alterations. Similarly, the injection of RGD-containing peptides had no detectable effect on somitogenesis or somite/segmental plate adhesion to the axis. On the basis of these data, we conclude that beta 1 integrins are necessary for normal somitic cell adhesions to the axis, but not somite segmentation and differentiation.

Amino Acid Sequence↗
PubMed1992

Clinical experience with reinforced, anchored intramuscular electrodes for functional neuromuscular stimulation.

Implanted intramuscular electrodes must remain functional for many years if functional neuromuscular stimulation (FNS) is to become a standard treatment in paralysed individuals. In initial trials we found that 5 of 11 coiled single-wire FNS electrodes implanted in 3 patients failed within 8 months. Consequently, we turned to a reinforced electrode comprising 2 multi-stranded, insulated wires tandem-wound on a prolene core and terminated by a prolene anchor or tine (after Mortimer et al., 1986, 1987). The electrodes were implanted with a translumbar aortogram needle, the teflon sheath of which enabled us to stimulate through the tip to guide placement. We have monitored the electrical and functional properties of 8 reinforced electrodes implanted in 2 incomplete quadriplegic patients over 22 months. Four of the electrodes were used for at least 1 h daily to exercise muscles or to provide FNS in gait. Electrical impedances, thresholds and elicited limb motion remained constant in all 8 electrodes over the test period. Disadvantages of the reinforced electrodes are (1) difficulty of eventual removal, and (2) risk of pathogenic infiltration is increased by the 3-filament structure (fortunately dense tissue encapsulation seems to mitigate infection). We conclude that tandem-wound, prolene-reinforced FNS electrodes are much more robust than previous single-coil designs and may form the basis for FNS devices of the future.

Adult↗
PubMed1992

A survey of vertebral burst-fracture management in Canada.

In the management of burst fractures, the role of direct surgical removal of retropulsed bony fragments encroaching upon the spinal canal (direct decompression) is controversial. A questionnaire was mailed to 65 neurosurgeons and 36 orthopedic surgeons across Canada to determine the current management of vertebral burst fractures and the willingness of these surgeons to participate in a longitudinal study of the effects of direct surgical decompression in the management of burst fractures. Sixty-nine (44 neurologic and 25 orthopedic) surgeons responded to the questionnaire. Of those who responded, 97% of the neurologic surgeons and 95% of the orthopedic surgeons stated that they used plain radiography and computed tomography in their pretreatment investigations, and at least 50% in each specialty repeated these investigations at follow-up examinations. Standard tomography, magnetic resonance imaging and myelography were used less frequently both before and after surgery. There were no significant differences between specialties in the use of tests. Neurologic status and the treating surgeon's specialty were found to significantly influence management of burst fractures. According to 56% of neurologic surgeons and 81% of orthopedic surgeons, neurologically intact patients were usually treated with stabilization only (p less than 0.05). The greater number of neurosurgeons who used direct decompression was balanced by the number of orthopedic surgeons who used indirect decompression. Patients with partial, stable neurologic injuries were usually managed by direct decompression and stabilization according to 84% of the responding neurologic surgeons and 77% of the responding orthopedic surgeons.(ABSTRACT TRUNCATED AT 250 WORDS)

Canada↗
PubMed1991

Spine trauma and associated injuries.

A longitudinal, prospectively gathered data base of spine trauma has been developed. A review of 508 consecutive hospital admissions identified the presence of associated injuries in 240 (47%) individuals, most frequently involving head (26%), chest (24%), or long bones (23%). Twenty-two per cent had one associated injury, 15% had two, and 10% had three or more. Most spine fractures involved the lower cervical (29%) or thoracolumbar junction (21%). Comparisons of presence or absence of associated injuries and spine fracture level showed significant differences (p less than 0.001). Eighty-two per cent of thoracic fractures and 72% of lumbar fractures had associated injuries compared to 28% of lower cervical spine fractures. While there was no significant relationship between type of associated injury and spine fracture level, those with associated injuries were less likely to have a neural deficit (p less than 0.05). After hospital admission, there were seven deaths. Early assessment and transport of spine trauma victims must be carried out with appropriate management of associated injuries. Conversely, multiple trauma victims must be handled with due regard for a possible spine fracture. The value of spinal units with specially trained personnel is emphasized.

Adult↗
PubMed1990

Avian vasculogenesis and the distribution of collagens I, IV, laminin, and fibronectin in the heart primordia.

The heart-forming regions of the early embryo are composed of splanchnic mesoderm, endoderm, and the associated ECM. The ECM of the heart-forming regions in stage 7-9 chicken embryos was examined using immunofluorescence. Affinity purified antibodies to chicken collagens type I and IV, chicken fibronectin, and mouse laminin were used as probes. We report that (1) the basement membrane of the endoderm contains immunoreactive laminin and collagen IV; (2) the nascent basement membrane of the heart splanchnic mesoderm contains immunoreactive laminin, but not type IV collagen, and (3) the prominent ECM between the splanchnic mesoderm and the endoderm (the primitive-heart ECM) contains collagen IV, collagen I, fibronectin, but not laminin. In addition, we describe microscopic observations on the spatial relationship of cardiogenic cells to the primitive-heart ECM and the endodermal basement membrane.

Animals↗