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Biomedical subjects

C W Lewis

Publications and source records attributed to C W Lewis.

At least 19 recordsLinked to original sources

Assessment of subchondral bone mineral density in equine metacarpophalangeal and stifle joints.

Functional relationships between articular cartilage and underlying subchondral bone have been shown to be associated with the progression of osteoarthritis (OA). However, quantifiable factors substantiating this relationship do not exist. Therefore, the study objective involved quantifying subchondral bone mineral density (BMD) of the equine metacarpophalangeal (MCP) and stifle joints as a step in determining if regional subchondral BMD may be associated with OA changes. BMD was bilaterally quantified using dual energy xray absorptiometry (DEXA) for four subchondral regions: palmer and dorsal aspect of the medial 3rd metacarpal (MC3P, MC3D), medial femoral condyle (MFC), and the medial trochlear ridge (MTR). BMD (g/cm2) was measured using a 5.2 x 5.2 mm region of interest in the subchondral bone area. To account for the differences in thickness, BMD (g/cm2) was divided by sample thickness providing volumetric BMD (g/cm3). No significant effect of side on BMD values was found (p > 0.72). However, there were significant differences in BMD found between all regions (p < 0.05). The volumetric BMD of the MC3P region was significantly greater than the MC3D and the MC3D was greater than the MFC, while the MFC was greater than the MTR (MC3P > MC3D > MFC > MTR). The MCP regions had a higher volumetric BMD than the stifle regions possibly due to higher weight distribution, smaller articular surface area, and joint geometry. The adaptive bone structural variations between the regions studied were shown to be significant. Mechanical properties of the overlying cartilage are currently being analyzed to correlate with these results and provide a possible diagnostic method to investigate OA progression.

Absorptiometry, Photon↗

Use of the Dermatology Life Quality Index (DLQI) in a midwestern US urban clinic.

BACKGROUND: The Dermatology Life Quality Index (DLQI), a self-administered general dermatology quality of life instrument, was originally developed and published in a dermatology clinic at University Hospital of Wales. OBJECTIVE: Our goal was to test the feasibility of having patients answer the DLQI in a busy dermatology clinic and to find out to what extent results vary from those published in Wales. We also wanted to examine the validity of the index in terms of the correlation between DLQI scores and stage of illness (disease severity). METHODS: We administered the DLQI to 200 consecutive patients who were seen in a dermatology clinic at Indiana University Medical Center. Results were examined in light of results found by those who originated the DLQI. A pilot group of patients were given the DLQI and rated for severity of disease by means of the Dermatology Index of Disease Severity (DIDS). RESULTS: Overall, the DLQI is easy to administer and can be completed within 3 minutes. The scores in our study were compatible with those previously reported by the DLQI originators. There was a "ceiling" effect in that 11% of the patients indicated no quality of life impairment on the DLQI rating. This index shows stratification with severity of disease. CONCLUSION: The DLQI is an easy and efficient instrument for assessing quality of life in dermatology patients. Patients needed minimal assistance with the form. Our results were similar to those of the DLQI originators, and this further shows reliability and validity of the DLQI. In addition, this study further supports the use of DLQI as a quality of life instrument suitable for use in international studies.

Adolescent↗

The effect of immobilization on rotator cuff healing using modified Mason-Allen stitches: a biomechanical study in sheep.

Long-term biomechanical integrity of the surgical site is crucial to the outcome of rotator cuff repair. Usually after rotator-cuff surgery, the arm is immobilized for 6-12 weeks to minimize disruption at the healing site. Unfortunately, currently there is very little clinical data on the effects of immobilization after rotator cuff surgery. This study analyzed the effect of immobilization on rotator cuff healing by comparing the healing strength of the tendon in a bone trough using a sheep model. In sixteen (16) female adult sheep, the right infraspinatus tendons were reattached into a bone trough using a modified Mason-Allen suture pattern. After surgery, each sheep was randomly assigned into either an immobilized or non-immobilized treatment group. The immobilized group was fitted with a softball taped under the foot to restrict limb movement for 6 weeks. The non-immobilized treatment group was allowed to fully bear weight on the treated shoulder. At 26 weeks, the animals were sacrificed and the surgical shoulders were harvested and stored in a -30 degrees C freezer. Biomechanical testing was performed using a MTS 809 Axial/Torsional Servohydraulic System. Special cryo-grips were used to test the infraspinatus tendon-bone interface in anatomical alignment. All samples were preloaded with 10 +/- 5 N, and then force was measured during a crosshead displacement of 500 mm/min until failure. Force and displacement were acquired at 100 Hz and used to calculate load-to-failure and stiffness of the bone-tendon interface. The load-to-failure (N) and stiffness (N/cm) were determined for both treatment groups. For the non-immobilized group, the loads to failure and stiffness means were 2571.95 +/- 329.9 N and 2319.09 +/- 457.72 N/cm. The immobilized group means were 2954.42 +/- 473.52 N (load-to-failure) and 2579.13 +/- 383.51 N/cm (stiffness). A two-tailed two-samples unequal variance student t-test with significance set at 0.05, found no significant difference between the treatment groups for load-to-failure (p = 0.2174) and stiffness (p = 0.8286).

Animals↗

The role of the pediatrician in the oral health of children: A national survey.

OBJECTIVES: To assess pediatricians' knowledge, attitudes, and professional experience regarding oral health, and to determine willingness to incorporate fluoride varnish into their practices. BACKGROUND: Poor and minority children suffer disproportionately from dental caries and have limited access to dental care. In a recent analysis of national survey data, the General Accounting Office reported that poor children had 5 times more untreated decay than did children from higher income families. Untreated decay can lead to problems with eating, speaking, and attending to learning. Children who are poor suffer 12 times the number of restricted activity days because of dental problems, compared with more affluent children. Despite higher rates of dental decay, poor children had one half the number of dental visits compared with higher income children in 1996. Medicaid's Early Periodic Screening Diagnosis and Treatment (EPSDT) program is intended to provide regular dental screenings and appropriate treatment but has apparently played a limited role in improving access to dental care for poor children. According to a report by the Office of the Inspector General of the Department of Health and Human Services, only 20% of children under 21 years of age, who were enrolled in Medicaid and eligible for EPSDT, actually received preventive dental services. By increasing their involvement in oral health prevention during well-child care visits, pediatricians may be able to play an important role in improving the dental health of their patients who have difficulty obtaining access to professional dental care. However, it is unclear to what degree pediatricians are knowledgeable about preventive oral health and the extent to which they may already be participating in prevention and assessment. Also, little is known about the incidence of dental problems in pediatric practice, and whether pediatricians perceive barriers to their patients' receiving professional dental care. Finally, it is important to know how pediatricians value the promotion of oral health and whether they would be willing to take on additional activities aimed at its improvement. We addressed these questions in a national survey of pediatricians. DESIGN: We surveyed a national sample of 1600 pediatricians randomly selected from the American Medical Association Master File to assess their knowledge, current practice, and opinion on their role in the promotion of oral health; experience with dental decay among patients and in referring patients for professional dental care; and willingness to apply fluoride varnish. RESULTS: Of 1386 eligible survey recipients, 862 returned surveys for a response rate of 62%. Respondents reported seeing dental problems regularly. Two thirds of respondents observed caries in their school-aged patients at least once a month. Of the respondents, 55% reported difficulty achieving successful dental referrals for their uninsured patients and 38% reported difficulty referring their Medicaid patients. More than 90% of the respondents agreed that they had an important role in identifying dental problems and counseling families on the prevention of caries. Moreover, respondents were interested in increasing their involvement: 74% expressed a willingness to apply fluoride varnish in their practices. One half of the respondents, however, reported no previous training in dental health issues during medical school or residency, and only 9% correctly answered all 4 knowledge questions. CONCLUSION: Access to dental care and unmet dental health needs are serious, under addressed problems for poor and minority children in the United States. In promoting preventive oral health, pediatricians benefit all children and particularly the underserved. We know of 2 states, Washington and North Carolina, that have acknowledged, through the provision of reimbursement, that pediatricians have a unique opportunity at well-child care visits to provide caries prevention c

Child↗

Intracardiac transplantation of skeletal myoblasts yields two populations of striated cells in situ.

BACKGROUND: Adult heart lacks stem cells and cannot effectively regenerate. In contrast, skeletal muscle is constantly undergoing repair. We proposed to transplant immature skeletal myoblasts into injured myocardium. METHODS: Approximately 7x10(6) soleus skeletal myoblasts were expanded in vitro from adult New Zealand White rabbits (n = 23) whose posterior left ventricle was cryoinjured to create a transmural lesion. Autologous myoblasts (n = 18) or saline (n = 5) was transplanted into the central cryolesion at the time of injury (n = 6) or 1 week later (n = 12). Hearts were harvested 2 weeks after injection. RESULTS: Myoblast transfer did not incur further morbidity. After cryolesion, grossly, a 1.6-cm epicardial hemorrhagic lesion could be seen. Histologically, the transmural lesion contained inflammatory cells and active scarring but no viable cardiomyocytes. Electron microscopy demonstrated a predominance of collagen and fibroblasts. Nine hearts contained multinucleated cells within the cryolesion that covered approximately 75% of the central cryolesion in 17% of animals. Immunohistochemical analysis confirmed their skeletal muscle origin. At the periphery of the lesion, isolated clusters of nonskeletal muscle cells could be visualized (n = 12) that resembled immature cardiocytes. CONCLUSIONS: Autologous skeletal myoblasts can regenerate viable striated tissue within damaged myocardium. Myoblast transfer warrants further investigation as a new method for improving myocardial performance within infarcted myocardium.

Animals↗

Increased cytotoxicity of food-borne mycotoxins toward human cell lines in vitro via enhanced cytochrome p450 expression using the MTT bioassay.

Eight food-borne mycotoxins epidemiologically implicated in human disease were tested for their cytotoxic effects on human cells previously immortalised and transfected to introduce human cytochrome p450 (CYP 450) genes. Such cells retain many characteristics of normal cell growth and differentiation while simultaneously having the potential of either increasing or decreasing the metabolic activity (cytotoxicity) of the challenging mycotoxins. The MTT assay provided an indication of cytotoxicity. Of the nine CYP450s introduced CYP1A2 was most effective, rendering the cells 540 times more sensitive than the control cells to aflatoxin B1, 28 times more sensitive to aflatoxin G1 and 8-fold more sensitive to ochratoxin A. CYP3A4 resulted in the cells being 211 times more toxic to aflatoxin B1 and 8-fold more toxic to aflatoxin G1 while CYP 2A6, CYP 3A5 and CYP 2E1 also produced observable effects. No increase in metabolic activity was found using cyclopiazonic acid, deoxynivalenol, fumonisin B1, patulin or T-2 toxin. CD5Os were calculated for the mycotoxins against the non-CYP-introduced control cells. There was almost a five order of magnitude difference between the most toxic, T-2 toxin (CD50 0.0057 microgram/ml) and the least toxic, fumonisin B1 (CD50 476.2 micrograms/ml). In vitro biological assays thus provide an excellent system for quantifying the often low CD50s expressed by mycotoxins in foods.

Biological Assay↗

Comparison of tunnel suture and suture anchor methods as a function of time in a sheep model.

There is little quantitative information available on the required healing time after a rotator cuff surgery. This study evaluated two surgical procedures by comparing the healing strength as a function of time of the tendon in a bone trough using a sheep model. The two surgical procedures compared were bioabsorbable suture anchors and bone tunnel suture technique. The infraspinatus tendon was split in half and procedure (suture anchor/tunnel suture) locations were randomly allocated to the proximal or distal half of the tendon at the healing time points of 0, 3, 6, 9, and 12 weeks with n = 6 at t = 0 and n = 8 in all other groups. At each time point, the surgical (right) and normal (left) shoulders were harvested and stored in a -30 degrees C freezer until testing. Biomechanical testing was performed using a MTS 809 Axial/Torsional Servohydraulic System. Special cryo-grips designed and built to test the infraspinatus tendon-bone interface in anatomical alignment were used. All samples were preloaded with 5 Newtons, and then force was measured during a crosshead displacement of 50 cm/min until failure. Force and displacement data were recorded to calculate load to failure and stiffness of the bone-tendon construct. There was only significant difference (95% CI) in mean tensile force at week 0, with the bone tunnel suture technique tensile force greater than the suture anchor method tensile force (p = 0.0261). There was no significant difference between stiffness means at any of the survival times.

Animals↗

An exploratory look at hydrocarbon data from the Photochemical Assessment Monitoring Stations network.

This paper describes some characteristics of speciated nonmethane organic compound (NMOC) data collected in 1994 at five Photochemical Assessment Monitoring Stations (PAMS) and archived in the U.S. Environmental Protection Agency's Aerometric Information Retrieval System (AIRS). Topics include data completeness, distribution of individual NMOCs in concentration categories relative to minimum detectable levels, percentage of total NMOC associated with the sum of the 55 PAMS target compounds, and use of scatterplots to diagnose chromatographic misidentification of compounds. This is an early examination of a database that is expanding rapidly, and the insights presented here may be useful to both the producers and future users of the data for establishing consistency and quality control.

Air Pollutants↗

A load-independent in vivo model for evaluating therapeutic interventions in injured myocardium.

Although cardiomyocyte damage is normally irreversible, gene therapy and somatic cell transfer offer potential for improving function in damaged regions of the heart. However, in ischemic models of injury, variability in depth, size, and location of damage compromises statistical evaluation of in vivo function. We have adapted cryoablation to create a reproducible, posterior, transmural lesion within rabbit myocardium in which small changes in function are measurable in vivo. Before and at 2 and 6 wk postinjury, in vivo left ventricular intracavitary pressure and myocardial segment length were measured. Regional indexes of performance, segmental stroke work (SW), and percent systolic shortening (SS) were significantly decreased (P < 0.001) postcryoinjury as was the slope (Mw) of the linear preload recruitable SW relationship between SW and end-diastolic segment length (P = 0.0001). Decreased SW, SS, and Mw correlated with wall thinning, loss of myocytes, presence of fibroblasts, and transmural scar formation. Reproducible changes in regional myocardial performance in vivo postcryoinjury suggest that this is a reasonable model for evaluating novel therapies for cardiovascular disease.

Animals↗

Outcomes research: an overview.

During the past few years there has been significant interest in studying methods that document outcomes of medical care. Outcomes management should result in higher quality health care at lower cost. However, what does outcomes research mean and how does it apply to dermatology and specifically to the individual dermatologist? This article reviews the evolution of medical outcomes research and presents the status of the current instruments, indices, and methods.

Dermatology↗

Reliability testing of the dermatology index of disease severity (DIDS). An index for staging the severity of cutaneous inflammatory disease.

OBJECTIVES: To describe a new severity of illness index for inflammatory skin disease called the Dermatology Index of Disease Severity (DIDS), and to show its preliminary use and reliability in staging disease in patients with psoriasis and dermatitis. DESIGN: Interobserver rating study using the DIDS with as many as 10 observers independently rating the same patient at a single point in time. SETTING: Ambulatory care clinics at an academic medical center with patients from various socioeconomic backgrounds. PATIENTS: Thirty-four patients with psoriasis and 15 patients with dermatitis were included in the study. MAIN OUTCOME MEASURES: The severity of illness for each patient was rated as 1 of 5 stages: 0, no evidence of clinical disease; I, limited disease; II, mild disease; III, moderate disease; and IV, severe disease. The degree of interobserver concordance was measured by the Cohen kappa statistic. RESULTS: All 5 stages were represented in the study of patients with psoriasis. The overall kappa statistic was 0.76, which is defined as substantial interobserver concordance. The use of the instrument in dermatitis showed good consensus in staging, where the kappa statistic was 0.41. CONCLUSION: We introduce an easy and efficient instrument for staging the severity of illness in inflammatory cutaneous diseases. The reliability of the DIDS is demonstrated in patients with psoriasis and in patients with dermatitis.

Adult↗