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Biomedical subjects

R C Anderson

Publications and source records attributed to R C Anderson.

At least 19 recordsLinked to original sources
PubMed1992

1,000 consecutive children with a cardiac malformation with 26- to 37-year follow-up.

The current status of 997 of 1,000 consecutive children with a cardiac malformation initially evaluated between 1952 and 1963 was determined. Of the 1000, 285 have died and the survivors have been followed up for periods of 26 to 37 years. Six hundred thirty-two are in excellent or good clinical condition, being asymptomatic and without planned need for further treatment. The other 80 have significant abnormalities, although 63 of these have few symptoms. Infective endocarditis occurred in 12 of 10,000 susceptible patient-years, with a lower rate in the past decade. Only 22 of the survivors are currently receiving cardiac medication. These data are derived from a group of patients initially seen during a period of time that cardiac surgery was being developed for congenital heart disease. Thus, the outlook should be even better for children who are currently undergoing treatment.

Arrhythmias, Cardiac↗
PubMed1992

Modeling the biomechanics of the mandible: a three-dimensional finite element study.

Three-dimensional finite element models of a partially edentulated human mandible were generated to calculate the mechanical response to simulated isometric biting and mastication loads. The level of mesh refinement was established via a convergence test and showed that a model with over 30,000 degrees of freedom was required to obtain analysis accuracy. The functional loading cases included muscle loading based on an algorithm that assigns muscle forces in accordance with muscle cross-sectional area, while maintaining static equilibrium. Results were found for isometric application of unilateral and bilateral bite and mastication loading, and two different sets of displacement boundary conditions were imposed at the condyles. The mechanical response is shown in terms of displacements, principal strains, and a new measure called the 'mechanical intensity scalar'. For each load case studied, there was substantial bending in the molar region of the corpus and high tensile strains in the anterior portion of the ramus.

Bicuspid↗
PubMed1992

Psychological adjustment following work-related hand injury: 18-month follow-up.

Severe, work-related hand injuries are often accompanied by a significant number of psychological symptoms that are frequently associated with posttraumatic stress disorders. These symptoms occur in the following four domains of psychological functioning: cognitive, affective, physiological, and behavioral. This study examined the incidence of a variety of symptoms occurring with work-injured patients. Interviews were conducted at 1 week, 3 months, 6 months, 12 months, and 18 months after injury. Symptom frequencies were recorded. The results indicate that many of these symptoms were persistent 18 months later and continued to be significantly debilitating. The results support the need for psychological intervention after severe, work-related hand injuries.

Accidents, Occupational↗
PubMed1991

Measuring the effectiveness of the Star Parenting Program with parents of young children.

This study evaluated the effectiveness of the STAR Parenting Program, designed specifically for parents with children between the ages of 1 and 5 yr. The 8-hr. program was completed by 35 parents. There was a significant increase in parents' favorability and a significant decrease in anxiety afterwards. Parents also significantly lowered their expectations, reduced the emotionality of their reactions to their child's problem behaviors, and increased their use of time-out and tangible rewards following training. These changes were maintained at a 6-wk. follow-up.

Adult↗
PubMed1991

Worksite health promotion. The benefits of providing personal health status feedback and education programs to employees.

Discovering ways to initiate and maintain health related behavior changes is a growing concern to business and industry. This research supports previous data indicating that wellness programs offered at the worksite are significantly beneficial in assisting employees to change behavior. This research did not find significant benefits to the employees who obtained health status information prior to participating in a worksite health program; however, the health assessment tool was informative and may have been adequate to assist in behavior changing activities. Wellness programs are important factors for promoting health related behaviors; failure of this study to support the importance of assessment feedback does not negate the desirability of assessment as an important component of the corporate wellness program.

Adult↗
PubMed1990

A worksite parenting program.

With more and more companies offering wellness programs for their employees, it seems reasonable to offer parent training classes to employees as an educational tool and a means of coping with stress. A series of parenting classes was developed using the STAR Parenting Model. The STAR Model teaches parents to stop, think, ask, and respond to their children based on tenets of cognitive behavior management. Classes taught to faculty and staff of the university were well attended and participants indicated that the method positively altered their parenting practices. Parents are challenged by their young children and by their jobs and careers. Parenting education at work may help to ease some employee stress and improve their parenting practices.

Adaptation, Psychological↗
PubMed1990

Success and failure attributions in smoking cessation among men and women.

1. Smoking behavior is intermingled with a very complicated array of social and psychological processes which suggests the presence of sociocultural factors that directly influence smoking behavior. 2. Social and cultural factors which distinguish former smokers from smokers indicate that behavioral factors may be related to the ability to successfully stop smoking. 3. Evidence suggests that attributional patterns differ according to gender, with women being more external and employing more luck attributions than men. 4. When attribution and self-efficacy expectations were combined with demographic variables, increased understanding of the cessation process increased and predictive power of success in smoking cessation improved.

Cultural Characteristics↗
PubMed1988

The effect of post-sintering heat treatments on the fatigue properties of porous coated Ti-6Al-4V alloy.

Porous coated Ti-6Al-4V alloy implant systems provide a biocompatible interface between implant and bone, resulting in firm fixation and potential long-term retention via bony ingrowth. In order to achieve an acceptable porous coating structure, the sintering protocol for Ti-6Al-4V alloy systems often requires that the material be heat treated above the beta transus. This transforms the as-received equiaxed microstructure, recommended for surgical implants, to a lamellar alpha-beta distribution, which has been shown to have the worst fatigue properties of the most common structures attainable in Ti-6Al-4V alloy. However, post-sintering heat treatments may be used to improve these properties by producing microstructures more resistant to crack initiation and propagation. This study investigated the influence of microstructural variations on the fatigue properties of porous coated Ti-6Al-4V alloy material. Nonporous coated and porous coated Ti-6Al-4V alloy fatigue specimens were subjected to a standard sintering heat treatment to produce a lamellar microstructure. In addition, two post-sintering heat treatments were used to produce coarse and fine acicular microstructures. Rotating beam (reversed bending) fatigue testing was performed and the endurance limits determined for the noncoated and porous coated microstructures. The values determined were 668 MPa (noncoated as-received equiaxed), 394 MPa (noncoated lamellar), 488 MPa (non-coated coarse acicular), 494 MPa (noncoated fine acicular), 140 MPa (porous coated lamellar), 161 MPa (porous coated coarse acicular), and 162 MPa (porous coated fine acicular). The noncoated coarse and fine acicular specimens displayed an approximate 25% increase over the noncoated lamellar specimens. The porous coated coarse and fine acicular specimens showed an approximate 15% improvement over the porous coated lamellar specimens.

Alloys↗
PubMed1988

Nematode transmission patterns.

The transmission of nematode parasites of vertebrates is reviewed with special reference to the phenomena of monoxeny, heteroxeny, paratenesis, and precocity. Monoxeny is divided into 2 types. Primary monoxeny assumes that there was never an intermediate host in the transmission. Secondary monoxeny assumes the loss of an intermediate host during the course of evolution and its replacement by a tissue phase in the final host. Heteroxeny, or the use of intermediate hosts, is a common feature of many nematode groups. The Spirurida utilize arthropods, the Metastrongyloidea molluscs, and Ascaridida arthropods and vertebrates. Paratenesis, or the use of transport hosts, is a common feature of the transmission of nematode parasites of carnivores. It is postulated that in some instances paratenic hosts have become intermediate hosts and replaced the original intermediate host. Precocity in the development of nematodes in intermediate hosts (including what may have been paratenic hosts) is defined as growth and/or development beyond the expected. Its occurrence among the nematode parasites of vertebrates is reviewed. It is regarded as a transmission strategy which accelerates gamete production in the final host. Precocity could also provide the mechanism for the transfer of a parasite from a predator final host to a prey final host.

Animals↗
PubMed1987

Inhibition by SRI 63-072 and SRI 63-119 of PAF-acether and immune complex effects in the guinea pig.

We have examined two PAF-acether receptor antagonists, SRI 63-072 and SRI 63-119, for their ability to inhibit PAF-acether and immune complex effects in the guinea pig. Both compounds exhibited dose-dependent inhibition of bronchoconstriction and hemoconcentration induced by 0.1 micrograms kg-1 PAF-acether, where the ED50 values of SRI 63-072 were 0.3/0.4 mg kg-1 i.a. and 0.14/0.17 mg kg-1 i.a. for SRI 63-119 for each response, respectively. The d and 1 chiral forms of both antagonists were equipotent towards inhibition of hemoconcentration and bronchoconstriction, suggesting a lack of enantiomeric selectively. SRI 63-072 was further evaluated for its ability to inhibit dermal extravasation in the reverse passive Arthus reaction. Guinea pigs given 125I-BSA i.v as antigen and anti-BSA antibodies by intradermal injection exhibited plasma leakage that was dose- and time-dependent relative to the antibody amount. SRI 63-072 exhibited 46% maximal inhibition of dermal plasma leakage when injected in the skin (100 micrograms site-1 i.d.) with the antibody but less than 10% inhibition when administered intra-arterially (3.0 mg kg-1 i.a.) with the antigen. Therefore, these antagonists effectively inhibit systemic effects of PAF-acether and are partially effective towards inhibition of the dermal extravasation induced by immune complexes. Furthermore, unlike the enantiomeric differences between R and S PAF-acether, the chiral molecules of 63-119 and 63-072 effectively antagonized hemoconcentration and bronchoconstriction induced by PAF-acether.

Administration, Oral↗
PubMed1987

Unusual finding of encapsulated nematode larvae (Spiruroidea) in Bartramia longicauda and Numenius americanus (Charadriiformes) in western Canada.

Third-stage spiruroid larvae were found encapsulated on the serosa of the small and large intestines and in the mesentery of one of 15 adult upland sandpipers (Bartramia longicauda) from Manitoba, Canada, and three of 18 adult long-billed curlews (Numenius americanus) from Alberta, Canada. The larvae resemble third-stage larvae of Physocephalus sexalatus and birds may serve as a paratenic host of this unidentified spiruroid species.

Animals↗
PubMed1987

The use of silver nitrate staining and backscattered electron imaging to visualize nematode sensory structures.

Parasitic nematodes of the species Cosmocercoides variabilis were stained with silver nitrate and examined with backscattered electron imaging (BEI). Sensory papillae were selectively highlighted in backscatter images. Silver stain deposited on papillae was located on the papillary surface as well as on the underlying dendritic process. Portions of the body cuticle were also stained. Some cuticular staining was attributed to non-specific deposition of silver but, consistent patterns of cuticular staining were noted in the anterior and posterior regions. This observation suggests that some staining of the cuticle was specific. Results of this preliminary work suggest that BEI is a technique useful to the study of nematode form.

Animals↗
PubMed1987

Optimum pore size for bone cement fixation.

The interface shear properties of porous coated Ti-6Al-4V alloy embedded in bone cement were examined as a function of pore size. Cylindric Ti-6Al-4V alloy push-out specimens were coated with two layers of spheric powders having particle size ranges of 297-420 microns, 420-500 microns, 595-707 microns, and 850-1400 microns. Sintering resulted in mean pore sizes of 165, 285, 345, and 550 microns, respectively, and porosities in the range of 40%-44%. There was a statistically significant difference between the mean pore sizes obtained from the four particle size ranges. There were no differences between the mean porosities. The porous-coated specimens were embedded in bone cement and mechanical push-out testing was performed. Non-coated specimens having a satin surface finish were also embedded in bone cement and tested. The noncoated metal specimens displayed an interface shear strength of 4.2 +/- 0.4 MPa, whereas the shear strengths for the porous-coated specimens were significantly higher and increased as pore size increased. The mean interface shear strengths determined were 17.0 +/- 2.1 MPa (165 microns pore size), 18.1 +/- 2.3 MPa (285 micron pore size), 23.6 +/- 1.7 MPa (345 microns pore size), and 25.4 +/- 3.4 MPa (550 microns pore size). Significant differences in shear strength for the porous-coated specimens were found between the two smaller particle sizes and the two larger particle sizes. As pore size increased from 285 microns to 345 microns, a statistically significant increase in shear strength from 18.1 MPa to 23.6 MPa was observed.

Alloys↗
PubMed1986

Infection in renal transplant recipients. Current approaches to diagnosis, therapy, and prevention.

Despite dramatic improvements in patient and renal allograft survival, infections continue to be an important cause of post-transplantation morbidity and mortality. Most serious infections manifest clinically as febrile diseases, and immunosuppression-induced compromised cell-mediated immunity is the basis for the predominance of infections due to opportunistic intracellular microorganisms. Diagnostic evaluation is guided by the timing of fever after transplantation, epidemiologic factors, and evidence of specific organ system involvement. Although current therapy of bacterial and parasitic infections is usually effective, the management of deep-seated fungal infections remains highly unsatisfactory. Cytomegalovirus disease, the single most important infection in some transplant centers, frequently presents as a self-limited viral syndrome; however, multiple organs may be affected. New measures for the rapid diagnosis and treatment of this viral infection hold promise. A number of recommendations have been proposed to prevent infections in renal transplant recipients; however, continued progress will depend primarily upon further refinements in immunosuppressive therapy.

Anti-Bacterial Agents↗
PubMed1986

Platelet activating factor-induced ischemic bowel necrosis: the effect of PAF antagonists.

We have reported a model of ischemic bowel necrosis produced in the rat by injecting platelet activating factor (PAF) or PAF with bacterial endotoxin (LPS) into the mesenteric vasculature. In the present study, we examined the protecting effects of three PAF antagonists, i.e. (R,S)-3-[2-[(2-octadecylaminocarbonyloxymethyltetrahydro-2-fura nylmethoxy) -hydroxyphosphinyloxy]-ethyl]-thiazolium hydroxide inner salt 4-oxide (SRI 63-072), (+/-)-3-[4-[3-octadecylaminocarbonyloxy-2-methoxy)-propoxy]-butyl] -thiazolium bromide (SRI 63-119) and 1-O-hexadecyl-2RS-O-ethyl-3-O -(7-thiazolinoheptyl)-glycerol-methanesulfonate (ONO-6240), on PAF-induced bowel necrosis. The antagonists were injected into the vein 10 min before PAF. Two microgram of PAF or 20 micrograms LPS with 1 microgram of PAF were injected into the aorta above the renal arteries. The parameters assessed included blood pressure, hematocrit, white blood cell count, extent of bowel perfusion and microscopic changes of the bowel. We found that SRI 63-072 (3 mg/kg), SRI 63-119 (3 mg/kg) and ONO-6240 (2 mg/kg) significantly improved the initial hypotension, hemoconcentration and leukopenia caused by PAF. All three drugs also corrected the sustained hypotension and hypoperfusion and gross lesions of the bowel, although microscopic examination still revealed focal mild lesions. SRI 63-072 was also active at a much lower dose (0.3 mg/kg).

Animals↗
PubMed1986

The effect of post-sintering heat treatments on the tensile properties of Ti-6A1-4V alloy.

Previous studies have shown that the application of a porous coating to a solid substrate offers several advantages over current methods of implant fixation. However, the heat treatments required to sinter porous metal coatings have also been shown to cause significant decreases in the mechanical properties of the substrate. With Ti-6A1-4V alloy, sintering above the material beta transus results in a transformation from the as-received, equiaxed microstructure, recommended for surgical implants, to a lamellar alpha-beta microstructure. This lamellar structure has been shown to have inferior mechanical properties. In the present study, microstructural analysis and mechanical testing were performed on Ti-6A1-4V alloy subjected to various post-sintering heat treatments in an attempt to improve the mechanical properties. The microstructures examined were a fine and a coarse acicular alpha in a retained beta matrix. Tensile tests were performed on specimens containing these structures and results were compared with the lamellar and equiaxed microstructures. The fine acicular alpha structure was shown to exhibit the best tensile properties for the post-sintering Ti-6A1-4V alloy microstructures examined, displaying a 9.8% elongation value, as compared to the as-received, equiaxed microstructure value of 13.5%. This represents a significant improvement over the 5.1% value obtained with the lamellar microstructure.

Alloys↗