Alternatives to lifting concrete masonry blocks onto rebar: biomechanical and perceptual evaluations.

This study examined the use of and barriers to H-block and high lift grouting, two alternatives to lifting concrete masonry blocks onto vertical rebar. Peak and cumulative shoulder motions were evaluated, as well as adoption barriers: H-block cost and stakeholder perceptions. Results indicated that using the alternatives significantly decreased peak shoulder flexion (p < 0.001). A case study indicated that building cost was higher with H-block, but the difference was less than 2% of the total cost. Contractors and specifiers reported important differences in perceptions, work norms, and material use and practices. For example, 48% of specifiers reported that use of high lift grouting was the contractor's choice, while 28% of contractors thought it must be specified. Use of H-block or high-lift grouting should be considered as methods to reduce awkward upper extremity postures. Cost and stakeholders' other perceptions present barriers that are important considerations when developing diffusion strategies for these alternatives. PRACTITIONER SUMMARY: This study provides information from several perspectives about ergonomic controls for a high risk bricklaying task, which will benefit occupational safety experts, health professionals and ergonomists. It adds to the understanding of shoulder stresses, material cost and stakeholder perceptions that will contribute to developing effective diffusion strategies.

Altered activation of phospholipase D by lysophosphatidic acid and endothelin-1 in mouse embryo fibroblasts lacking phospholipase C-gamma1.

Lysophosphatidic acid (LPA) and endothelin-1 (ET-1) activate phospholipase D (PLD) in many cell types. To see if phospholipase C-gamma1 plays a role, we used embryonic fibroblasts from mice in which the PLCgamma1 gene was disrupted. Surprisingly, the effect of LPA on inositol phosphate accumulation was increased in these PLCgamma1-/- cells, whereas that of ET-1 was completely abrogated. When PLD activity was measured, the response to LPA was also enhanced and the response to ET-1 lost in the PLCgamma1-/- cells. Treatment of these cells with ionomycin and oleoyl acetyl glycerol to mimic PLC stimulation restored PLD activity. Treatment of either PLCgamma1+/+ and PLCgamma1-/- cells with tyrosine kinase inhibitors did not inhibit LPA- or ET-1-induced PLD activity. Moreover, LPA and ET-1 treatment of PLCgamma1+/+ and PLCgamma1-/- cells did not cause tyrosine phosphorylation of PLC-gamma1 or PLC-gamma2. In summary, these results show that the altered PLD responses to LPA and ET-1 in PLCgamma1-/- are due to changes in PLC activity and do not involve tyrosine kinase activity.

Epidermal toxicity of disinfectants.

The purpose of the present study was to investigate the capacity of various disinfectant chemicals to cause epithelial toxicity with repeated exposure. The abdominal area of 3-month old, experimental ICR/CD-1 mice was initially shaved, denuded with a depilatory agent and allowed to rest for 24 hours. Commercial preparations of iodophors, bleach, synthetic phenols, phenolic/alcohols, and glutaraldehydes were then sprayed onto the exposed abdominal tissue 8 times/day (0.8 ml spray) for 2 consecutive days. The applied disinfectant was allowed to dry between procedures. In comparison to controls sprayed with distilled water, each disinfectant stimulated some degree of epidermal changes. Resultant multiple brownish lesions showed local thickening and hardening. Histologically, epidermal changes ranged from mild hypertrophy to extensive epithelial erosion. A few inflammatory cells were occasionally detected in the epithelium. When present, dermal reactions ranged from a mild inflammation to focal areas of collagen degeneration. The results indicated that iodophors stimulated the mildest reactions, followed by the synthetic phenol preparations, bleach, phenolic/alcohols, and glutaraldehyde sprays. Similar assays using glutaraldehyde immersion sterilants/disinfectants produced marked tissue destruction.

Scanning electron micrographic effects of air-abrasion cavity preparation on human enamel and dentin.

Recent developments in technology and restorative materials have renewed interest in air abrasion as a means of tooth preparation. The technique, also called kinetic cavity preparation, uses kinetic energy to remove tooth structure. The purpose of this investigation was to use scanning electron microscopy to compare the effects of this technique to those of high-speed burs on extracted human teeth. Class V buccal preparations were made on five teeth with a No. 34 carbide bur used at 400,000 rpm and on 23 teeth with kinetic cavity preparation using differing combinations of aluminum oxide particle sizes and delivery pressures. Features of the specimens prepared at high speed included sharp line angles, chipping of the cavo-surface margin, and striated internal surfaces. Kinetic cavity preparations had rounded cavo-surface margins and internal line angles. The surfaces were microscopically rough and the dentinal tubules were occluded. There was little difference in appearance between specimens treated with various combinations of particle sizes and delivery pressures.

Scanning electron microscopic study of laser-induced morphologic changes of a coated enamel surface.

A low-energy Nd:YAG laser was used to irradiate extracted human teeth coated with a black energy-absorbent laser initiator in a study to determine the extent of the morphologic changes produced in the enamel surface. The laser initiator was applied to a cleaned enamel surface and irradiated at an energy output of 30 mJ or 75 mJ. Both energy levels produced morphologic changes of the surface. There was a sharp line of demarcation between the coated, irradiated area and the surrounding noncoated enamel surface. The scanning electron microscope view at the lower energy level showed that the surface had melted and reformed with numerous small, bubble-like inclusions. The 75 mJ energy level showed individual impact craters with shallow centers and raised edges containing numerous pores and large, bubble-like inclusions. Etching is a dental procedure in which an acid is normally used to remove a thin outer layer of the tooth structure. This is necessary to create a roughened, irregular surface in order to provide mechanical retention for dental restorative materials. The changes produced by the laser in this study suggest a simple, effective, and controlled method of etching the enamel surface of a tooth by altering its surface characteristics.

Subsurface morphologic changes of ND:YAG laser-etched enamel.

BACKGROUND AND OBJECTIVE: Etching the enamel surface with a Nd:YAG dental laser produces impact craters with cavities, micropores, and microfissures. This in vitro SEM study examined laser-etched enamel to determine the pattern and extent of subsurface changes. STUDY DESIGN/MATERIALS AND METHODS: The facial surface of 10 maxillary central incisor teeth were coated with a black initiator and laser-etched with a pulsed Nd:YAG laser (1.06 lambda, 75 mJ, 15 Hz, 320 microns fiber, 94 J/cm2 fluence). The facial surface of five teeth were plastic-embedded under a low vacuum, then demineralized in 10% formic acid. The other teeth were split incisoapically. All samples were prepared for SEM. RESULTS: Examination of the plastic impressions showed a delicate interlacing pattern of thin partitions and small knob-like expansions. Examination of the split teeth showed the penetration of microfissures into the enamel estimated at 10 microns. CONCLUSION: These subsurface alterations may provide space for the infiltration and mechanical retention of dental resin.

Comparison of work and time estimates by chiropractic physicians with those of medical and osteopathic providers.

BACKGROUND: Resource-based relative value scales (RBRVS) have become a standard method for identifying costs and determining reimbursement for physician services. Development of RBRVS systems and methods are reviewed, and the RBRVS concept of physician "work" is defined. OBJECTIVE: Results of work and time inputs from chiropractic physicians are compared with those reported by osteopathic and medical specialties. Last, implications for reimbursement of chiropractic fee services are discussed. METHODS: Total work, intraservice work, and time inputs for clinical vignettes reported by chiropractic, osteopathic, and medical physicians are compared. Data for chiropractic work and time reports were drawn from a national random sample of chiropractors conducted as part of a 1997 workers' compensation chiropractic fee schedule development project. Medical and osteopathic inputs were drawn from RBRVS research conducted at Harvard University under a federal contract reported in 1990. Both data sets used the same or similar clinical vignettes and similar methods. Comparisons of work and time inputs are made for clinical vignettes to assess whether work reported by chiropractors is of similar magnitude and variability as work reported by other specialties. RESULTS: Chiropractic inputs for vignettes related to evaluation and management services are similar to those reported by medical specialists and osteopathic physicians. The range of variation between chiropractic work input and other specialties is of similar magnitude to that within other specialties. Chiropractors report greater work input for radiologic interpretation and lower work input for manipulation services. CONCLUSIONS: Chiropractors seem to perform similar total "work" for evaluation and management services as other specialties. No basis exists for excluding chiropractors from using evaluation and management codes for reimbursement purposes on grounds of dissimilar physician time or work estimates. Greater work input by chiropractors in radiology interpretation may be related to a greater importance placed on findings in care planning. Consistently higher reports for osteopathic work input on manipulation are likely attributable to differences in reference vignettes used in the respective populations. Research with a common reference vignette used for manipulation providers is recommended, as is development of a single generic approach to coding for manipulation services.

Resource-Based Relative Value Scales: impacts and recommendations relative to chiropractic practice.

PURPOSE: The American health care financing and delivery system is changing at a rapid pace. As part of recent reform of payment systems for physician services, Medicare has adopted a resource-based relative value scale (RBRVS) that is becoming a national standard. Research has now documented characteristics of physicians' work and the overhead for providing specific health services for most medical specialties and disciplines. This information is being used to develop service descriptions (billing codes) and reimbursement levels. No such data exist relative to chiropractic, which may hinder chiropractic's efforts to be included in evolving reimbursement schemes. RBRVS and its relevance to chiropractic is reviewed, information on work levels and practice costs is discussed, chiropractic practice is reviewed and a research and policy agenda for documenting chiropractic work, overhead and service descriptions is provided. METHODOLOGY: A manual systemic review of available recent and relevant medical and chiropractic literature was undertaken to characterize how the RBRVS system for reimbursement of physician services was developed and implemented. Payer and trade association literature was used to determine what established work value and practice costs for DCs there are. Published payment scales from governmental commissions were also obtained. CONCLUSIONS: Resources are urgently needed to survey levels of work by chiropractors in providing their various health services. The methodology should be the one used by the Health Care Financing Administration to assess other specialties. A range of generic manipulation codes should be developed and tested in a similar fashion for submission for inclusion in Physician's Current Procedural Terminology (CPT). A seed range of descriptions is presented. A systematic collection of practice overhead costs and malpractice risk should be undertaken and documented using standardized methodology.

Sequential mesenteric lymph node histological response following Trichinella spiralis infection.

The histology of mouse secondary lymphoid tissue was examined following infection of Trichinella spiralis. ICR/CD-1 mice were orally infected with 200 T. spiralis and sacrificed at either 0, 3, 7, 14, 28 or 56 days after nematode administration. The animals were bled and sacrificed, and mesenteric lymph nodes were removed from each animal. They were fixed in 10% neutral buffered formalin, embedded in paraffin, and cut in 4-micron sections. Examination of serial sections demonstrated the sequential development of histological alteration in these regional lymph nodes. Hyperplasia was detected as early as 3 days after infection. Progressive changes occurring between 7 and 28 days after larval inoculation included hyperplasia with concurrent congestion of medullary sinuses, with increased numbers of neutrophils, histiocytes, lymphocytes, and eosinophils. Microscopic appearance of nodes removed from 56-day infected mice was similar to that noted for control tissues.

Two cases of incompatibility to carbon-coated subperiosteal implants.

Two cases of clinical incompatibility of carbon-coated subperiosteal implants are presented. The clinical history and the microscopic features of biopsy material of each case are reviewed. The histologic appearance of tissue from both cases presented scattered particles of carbon surrounded by lymphocytes, macrophages, plasma cells, and tissue eosinophils. Active phagocytosis and Russell's bodies were seen. Large masses of carbon were surrounded by connective tissue. The clinical and microscopic findings suggest an immunologic rejection of the implant-coating material.

Drug information course for pharmacy staff development.

An interactive course in drug information skills developed for pharmacists at a not-for-profit, tertiary-care hospital is described. Faculty members from the area school of pharmacy developed, taught, and evaluated the program. Before the course was developed, pharmacy staff members were asked to rate their drug information skills; the pharmacists' responses indicated their belief that they were not proficient enough in the skills needed in daily practice. The course content and format were refined after 11 pharmacists completed a pilot program. A handbook was developed that contained objectives, session outlines, and literature for each of the six topics chosen for the course. Although the handbook was the primary teaching aid, wall charts and computer demonstrations were also used. Sessions were structured for the needs of adult students by using a small-group discussion format that emphasized the practical relevance of the information and encouraged participants to share personal experiences. Each session was offered on two separate days to facilitate attendance. Those who completed the course received credit for 12 contact hours of continuing education. Of 16 pharmacists enrolled in the course, 11 completed it. An interactive course in drug information skills, developed to meet the needs of hospital pharmacists, was well accepted because it incorporated personal experiences, small-group activities, and flexible scheduling.

Establishment of total and intraservice work by chiropractic physicians in providing spinal manipulative therapy and evaluation and management services.

OBJECTIVE: To develop and test a self-report survey instrument that measures the work performed by chiropractors in the delivery of evaluation and management (E/M) services and spinal manipulative therapy (SMT). Work is one leg of a triad used to develop Resource-Based Relative Values Scales (RBRVS) for physician reimbursement. DESIGN: Reliability study modeled after a tool designed and tested by economists at Harvard University School of Public Health in the development of relative values scales for physician reimbursement. The survey instrument uses magnitude estimation as a means of obtaining reliable and valid measures of the subjective assessments of the dimensions of a physicians work. SAMPLE: A random national sample was drawn from all members of the American Chiropractic Association. RESULTS: Estimates of the work performed by chiropractors in providing E/M and SMT services were established. The reliability of work ratings indicated that chiropractors agree closely on their ratings for work. The validity of the results indicated a high degree of consistency in rating work, which implies that the results are realistic. A review of demographics suggested that the survey population was representative of the general population of chiropractors. CONCLUSIONS: This study generated valid and reliable estimates of the work performed by chiropractors in providing E/M and SMT services. Work is one of three components used in the development of RBRVS, the method of physician reimbursement that is currently the industry standard. By quantifying the work required in providing services, chiropractors can now develop RBRVS. Additionally, the evidence-based data on work collected here can be used for a comparison with the work of similar services provided by other specialists. This can facilitate the use or modification of service description codes for use by chiropractic physicians.

Role of Rho family proteins in phospholipase D activation by growth factors.

Treatment of fibroblasts with growth factors results in activation of phospholipase D (PLD). In order to determine the role of the Rho family of small GTPases in growth factor-mediated PLD activation, we used cells transfected with wild type and mutant Rac1. In response to epidermal growth factor (EGF), PLD activity was greatly increased in Rat1 fibroblasts expressing wild type Rac1 (wtRac1), and completely abrogated in cells expressing dominant negative N17Rac1, consistent with Rac1 mediating the action of this growth factor. In contrast, in cells treated with platelet-derived growth factor (PDGF) or phorbol ester, the wtRac1 cells showed little or no enhancement of PLD activity, and the response was not affected in the N17Rac1 cells, implying that Rac1 played a minimal role in the activation of PLD by PDGF or protein kinase C. Both growth factors produced an attenuated PLD response in cells expressing constitutively active V12Rac1, but these cells showed other changes, including altered morphology, increased basal PLD, and decreased growth factor receptor autophosphorylation. The effects of EGF and PDGF on phosphoinositide phospholipase C activity were not enhanced in cells expressing wtRac1 or inhibited in those expressing N17Rac1. In cells expressing constitutively active V12Rac1, basal phosphoinositide phospholipase C was elevated, but there were no significant effects of EGF or PDGF. We used C3 transferase of Clostridium botulinum, which ADP-ribosylates and inactivates RhoA, to investigate the involvement of RhoA in the activation of PLD by PDGF. Cells expressing wtRac1 and N17Rac1 showed a decreased PLD in response to PDGF when treated with C3 transferase, indicating a role for RhoA. In summary, these data indicate a major role for Rac1 in the activation of PLD by EGF, but not PDGF or protein kinase C.

Analysis of platelet-derived growth factor-induced phospholipase D activation in mouse embryo fibroblasts lacking phospholipase C-gamma1.

Platelet-derived growth factor (PDGF) activates phospholipase D (PLD) in mouse embryo fibroblasts (MEFs). In order to investigate a role for phospholipase C-gamma1 (PLC-gamma1), we used targeted disruption of the Plcg1 gene in the mouse to develop Plcg1(+/+) and Plcg1(-/-) cell lines. Plcg1(+/+) MEFs treated with PDGF showed a time- and dose-dependent increase in the production of total inositol phosphates that was substantially reduced in Plcg1(-/-) cells. Plcg1(+/+) cells also showed a PDGF-induced increase in PLD activity that had a similar dose dependence to the PLC response but was down-regulated after 15 min. Phospholipase D activity, however, was markedly reduced in Plcg1(-/-) cells. The PDGF-induced inositol phosphate formation and the PLD activity that remained in the Plcg1(-/-) cells could be attributed to the presence of phospholipase C-gamma2 (PLC-gamma2) in the Plcg1(-/-) cells. The PLC-gamma2 expressed in the Plcg1(-/-) cells was phosphorylated on tyrosine in response to PDGF treatment, and a small but significant fraction of the Plcg1(-/-) cells showed Ca2+ mobilization in response to PDGF, suggesting that the PLC-gamma2 expressed in the Plcg1(-/-) cells was activated in response to PDGF. The inhibition of PDGF-induced phospholipid hydrolysis in Plcg1(-/-) cells was not due to differences in the level of PDGF receptor or in the ability of PDGF to cause autophosphorylation of the receptor. Upon treatment of the Plcg1(-/-) cells with oleoylacetylglycerol and the Ca2+ ionophore ionomycin to mimic the effect of PLC-gamma1, PLD activity was restored. The targeted disruption of Plcg1 did not result in universal changes in the cell signaling pathways of Plcg1(-/-) cells, because the phosphorylation of mitogen-activated protein kinase was similar in Plcg1(+/+) and Plcg1(-/-) cells. Because increased plasma membrane ruffles occurred in both Plcg1(+/+) and Plcg1(-/-) cells following PDGF treatment, it is possible neither PLC nor PLD are necessary for this growth factor response. In summary, these data indicate that PLC-gamma is required for growth factor-induced activation of PLD in MEFs.

Comparative efficacy of ketoconazole and mebendazole in experimental trichinosis.

The therapeutic efficacy of ketoconazole and mebendazole was studied in ICR/CD-1 mice infected with Trichinella spiralis for 17 to 20 weeks. Efficacy of both drugs was over 70% when compared with results in control mice. This study indicates that both ketoconazole and mebendazole should be considered in the treatment of trichinosis in humans.