Search PubMed⌕ Search

Biomedical subjects

R B Irwin

Publications and source records attributed to R B Irwin.

At least 19 recordsLinked to original sources
PubMed2003

The correlation between ion beam/material interactions and practical FIB specimen preparation.

The focused ion beam (FIB) tool has been successfully used as both a stand alone analytical instrument and a means to prepare specimens for subsequent analysis by SEM, TEM, SIMS, XPS, and AUGER. In this work, special emphasis is given to TEM specimen preparation by the FIB lift-out technique. The fundamental ion/solid interactions that govern the FIB milling process are examined and discussed with respect to the preparation of electron transparent membranes. TRIM, a Monte Carlo simulation code, is used to physically model variables that influence FIB sputtering behavior. The results of such computer generated models are compared with empirical observations in a number of materials processed with an FEI 611 FIB workstation. The roles of incident ion attack angle, beam current, trench geometry, raster pattern, and target-material-dependent removal rates are considered. These interrelationships are used to explain observed phenomena and predict expected milling behaviors, thus increasing the potential for the FIB to be used more efficiently with reproducible results.

Computer Simulation↗
PubMed2001

Coralline hydroxyapatite as bone substitute in orthopedic oncology.

We retrospectively reviewed the results of 71 consecutive patients managed with coralline hydroxyapatite (Pro-Osteon 500; Interpore Cross International) for bone defects produced as a result of surgical extirpation of bone tumors. All patients underwent a thorough physical examination and a radiographic evaluation at baseline and follow-up by the same senior surgeon (R.B.I.). Seventy-one patients were followed up for an average of 2.4 years (range, 8.1 months to 3.5 years); mean age of female patients was 39.8 years and that of male patients was 30 years. The functional status of patients at follow-up was evaluated based on comparison with preoperative functional status. Radiographic evaluation was performed and graded as follows: stage I (obvious margins), stage II (hazy margins), and stage III (obvious incorporation). The average time of return of preoperative function was 7.6 weeks. There were 3 major and 9 minor complications. We conclude that coralline hydroxyapatite graft in the form of Pro-Osteon 500 is a viable option for the management of bone defects in orthopedic oncology.

Adolescent↗
PubMed1998

Applications of the FIB lift-out technique for TEM specimen preparation.

A site-specific technique for cross-section transmission electron microscopy specimen preparation of difficult materials is presented. A focused ion beam was used to slice an electron transparent membrane from a specific area of interest within a bulk sample. Micromanipulation lift-out procedures were then used to transport the electron-transparent specimen to a carbon-coated copper grid for subsequent TEM analysis. The FIB (focused ion beam) lift-out technique is a fast method for the preparation of site-specific TEM specimens. The versatility of this technique is demonstrated by presenting cross-sectioned TEM specimens from several types of materials systems, including a multi-layered integrated circuit on a Si substrate, a galvanized steel, a polycrystalline SiC ceramic fiber, and a ZnSe optical ceramic. These specimens have both complex surface geometry and interfaces with complex chemistry. FIB milling was performed sequentially through different layers of cross-sectioned materials so that preferential sputtering was not a factor in preparing TEM specimens. The FIB lift-out method for TEM analysis is a useful technique for the study of complex materials systems for TEM analysis.

Ceramics↗
PubMed1997

Low-grade central osteosarcoma resembling fibrous dysplasia. A report of two cases.

We describe 2 cases of low-grade central osteosarcoma mimicking fibrous dysplasia and present a review of the literature. These cases illustrate the importance of obtaining a large representative sample of tumor in suspicious lesions, because it may be difficult or impossible to histologically distinguish low-grade central osteosarcoma from a benign lesion with limited samples from a core biopsy or needle aspiration. The treatment of choice for low-grade central osteosarcoma is resection with wide surgical margins or, if limb salvage is not technically feasible, amputation.

Adolescent↗
PubMed1996

An unusual presentation of telangiectatic osteosarcoma.

Telangiectatic osteosarcoma (TOS) is a rare subtype of osteosarcoma that accounts for approximately 2% of all osteosarcomas. Presented is a case of a sacral mass that was originally thought to be a chordoma and was treated surgically but on pathologic examination was diagnosed as a TOS. A review of the literature on other sacral lesions is provided. The intention for presenting this case is twofold: to make physicians aware of the differential diagnoses of sacral lesions and to report an unusual presentation of this rare tumor.

Adult↗
PubMed1996

Aneurysmal bone cyst of the patella.

Aneurysmal bone cysts are uncommon lesions accounting for less than 1% of reported primary bone tumors. This case study reports the ninth primary aneurysmal bone cyst of the patella, and the second to be reported in a white male patient. The scarcity of reports in this vulnerable site may refute trauma as the cause. If the articular surface is spared, this lesion can be treated successfully by curettage and bone grafting, once a definitive diagnosis is made.

Adolescent↗
PubMed1992

Clear cell sarcoma presenting as an interdigital neuroma.

The incidence of malignant soft-tissue sarcomas in the general population is approximately 1.4 per 100,000. Approximately 2% of all cancer deaths are attributable to these tumors. Presented is a case history of a soft-tissue malignant neoplasm that was originally thought to be an interdigital neuroma and that eventually required a modified Chopart's amputation. A review of the literature is presented on other soft-tissue malignant tumors that have an affinity for the foot and ankle. The intention of presenting this case is to caution physicians that malignant lesions can simulate a benign process and should always be considered in the differential diagnosis of any foot mass.

Adolescent↗
PubMed1991

Osteolytic monostotic Paget's disease of the fifth lumbar vertebra. A case report.

Osteolytic monostotic Paget's disease or osteitis deformans of the fifth lumbar vertebra occurred in a 55-year-old woman. An isolated lytic process involving the entire vertebral body and posterior elements and an open biopsy showed extensive remodeling with cement lines, myelofibrosis, and osteoclastic resorption typical of Paget's disease.

Female↗
PubMed1985

Mediator release in local heat urticaria: protection with combined H1 and H2 antagonists.

Two patients with local heat urticaria were examined for evidence of histamine release and for changes in mast cell morphology after local heat challenge. Both patients demonstrated significant release of histamine into the draining venous blood in the challenged arm. Biopsy specimens revealed mucosal edema after 30 min, followed by a mononuclear, perivascular infiltrate by 6 hr, and increasing in intensity by 24 hr. Degranulated mast cells were observed by electron microscopy. Heat challenge was repeated after treatment with hydroxyzine, cimetidine, or a combination of both drugs. Neither hydroxyzine nor cimetidine alone affected the clinical response to challenge, but both drugs together completely abolished the clinical response. In addition, the combination of both drugs taken regularly completely prevented symptoms. This observation suggests that histamine is one of the major mediators of this disorder and that both H1 and H2 receptors are operative.

Adult↗
PubMed1981

Training speech pathologists through microtherapy.

Two microtraining methods were evaluated for training speech pathologists in the acquisition of skills utilized in treating misarticulations. Fifteen subjects in an introductory class in speech pathology were randomly placed in two groups (modeling, video replay, and counseling versus video replay and counseling). The training included reading a manual about the skills and a sequence of three teach sessions. The control group did not view the video model. According to the results, the model group made a greater gain score (M = 8.38) than the nonmodel group (M = 3.88). Significant gains were made for both experimental groups between teach sessions one and two, but no significant gains were made between the second and third teach sessions.

Books↗
PubMed1981

Video self-confrontation in speech pathology.

Fifteen students in speech pathology observed and reacted to video replay of clinical sessions, representing presituation and postsituation tests with intervening microtherapy sessions, which were also videotaped and replayed. Reactions to video replays were made to questions. Experience through microtherapy and video self-confrontation gives more evidence of reduction of anxiety. Further study of the concerns of clinical trainees through video self-confrontation in a microtraining format is recommended.

Anxiety↗