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Biomedical subjects

M J Joyce

Publications and source records attributed to M J Joyce.

At least 19 recordsLinked to original sources
PubMed2006

The design of a portable cosmic ray three-band neutron detector.

The design of a portable three-band cosmic-ray neutron detector is reported in this article. This instrument has been designed to characterise cosmic ray neutron fields in the upper atmosphere and in cosmic reference field facilities. The design utilises a spherical moderator with a layer of spallation material covering a central (3)He proportional counter. The instrument incorporates twelve lithium-coated diodes, six on the outside of the polyethylene layer and six placed within the structure. The dimensions, materials and arrangement of these in the instrument have been optimised with MCNPX to provide a compromise between the requirements of portability and spectral response.

Cosmic Radiation↗
PubMed2005

Multicenter evaluation of a Candida albicans peptide nucleic acid fluorescent in situ hybridization probe for characterization of yeast isolates from blood cultures.

We evaluated aliquots from 244 clinical blood culture bottles that demonstrated yeasts on Gram stain using a Candida albicans peptide nucleic acid (PNA) fluorescent in situ hybridization (FISH) probe. The sensitivity, specificity, positive predictive value, and negative predictive value of the C. albicans PNA FISH test in this study were 99%, 100%, 100%, and 99.3%, respectively.

Blood↗
PubMed2000

American association of tissue banks: a historical reflection upon entering the 21st century.

The American Association of Tissue Banks (AATB) is a scientific, not-for-profit, peer-group organization founded in 1976 to facilitate the provision of transplantable tissues of uniform high quality in quantities sufficient to meet national needs. The Association was created well before there was governmental oversight of tissue banking. The organization consists of individuals involved in tissue banking, medical users, and scientists in the field. Current structure consists of a 13-member Board of Governors with specific subgroups including Musculoskeletal, Reproductive, Skin, Tissue Bank Councils and Council of Accredited Tissue Banks. A historical review shows the evolution from development of guidelines to publication of standards, and from an inspection conducted by peers to one conducted by an independent, trained professional inspector. Association growth and historical accomplishments are highlighted.

Journal Article↗
PubMed1997

Paraarticular osteochondroma of the knee: report of 2 cases and review of the literature.

Paraarticular osteochondromas are unusual osteocartilaginous tumors that arise in the soft tissue adjacent to a joint. Their pathogenesis and classification are controversial, and worrisome histologic features make the distinction from chondrosarcoma difficult on morphologic grounds alone. Two cases of paraarticular osteochondroma of the knee arising in patients 66 and 75 years of age are reported in this study. Although the exact biologic nature of these tumors is not well characterized, limited data suggest that they will behave in benign fashion, similar to soft tissue chondromas. Paraarticular osteochondromas should be recognized to avoid unnecessarily aggressive surgical management.

Aged↗
PubMed1996

Dedifferentiated chondrosarcoma with rhabdomyosarcomatous differentiation.

Dedifferentiated chondrosarcomas are primary bone tumors characterized by the presence of both low-grade cartilaginous and high-grade sarcomatous components. The high-grade component usually shows histologic features of either malignant fibrous histiocytoma or fibrosarcoma. We are aware of only 10 published cases in which the high-grade component showed rhabdomyosarcomatous differentiation. To further clarify the clinical, radiographic, and pathologic features of this unusual variant, we report three additional cases of dedifferentiated chondrosarcoma with rhabdomyosarcomatous differentiation. The patients included two men and one woman; their mean age was 63 years. Tumors originated in the pelvis (ilium), scapula, and tibia. Two patients presented with radiographic findings typical of dedifferentiated chondrosarcoma, including a geographic, lytic lesion with areas of mineralization suggestive of cartilage in close association with a permeative component. The third patient presented with a primarily lytic, destructive lesion of the right iliac wing. Histologically, the tumors contained lobules of well-differentiated chondrosarcoma associated with a high-grade sarcoma with prominent rhabdomyoblasts. Immunohistochemical stains for actin and desmin were positive in all three tumors, and electron microscopy revealed evidence of skeletal muscle differentiation. All three patients died with metastatic disease, 1, 6, and 12 months postoperatively. This histologic variant of dedifferentiated chondrosarcoma is rare, but it shows radiographic and clinical features similar to "conventional" dedifferentiated chondrosarcoma, including a very poor prognosis.

Aged↗
PubMed1993

Open tibial fractures with severe soft-tissue loss. Limb salvage compared with below-the-knee amputation.

The long-term outcomes and the quality of life were studied in patients who had had an open fracture of the tibial shaft with severe soft-tissue loss. Limb salvage with a free flap was attempted in twenty-seven patients (sixteen of whom had a successful procedure and were examined personally by us), while eighteen patients were managed concurrently with an early below-the-knee amputation. Soft-tissue coverage was successful in all but one patient in whom limb salvage had been attempted. Ultimately, however, five extremities were amputated, with an infection at the site of a non-union being the most common reason for amputation. The patients who had had limb salvage had more complications (p < 0.001), more operative procedures (p < 0.001), and a longer stay in the hospital (p < 0.05) than the patients who had had an early below-the-knee amputation. The long-term functional results for sixteen patients who had had a successful limb-salvage procedure (average duration of follow-up, thirty-five months) were compared with those for eighteen patients who had had a below-the-knee amputation (average duration of follow-up, forty-four months). The patients who had had a successful limb-salvage procedure took significantly more time to achieve full weight-bearing (p < 0.05), were less willing or able to work (p < 0.01), and had higher hospital charges (p < 0.006) than the patients who had been managed with an early below-the-knee amputation. They also had a significant decrease in motion at the ankle and subtalar joint in the injured leg compared with the contralateral leg (p < 0.001). A quality-of-life evaluation was possible for only thirteen of the patients who had had a successful limb-salvage procedure and for sixteen of the patients who had had a below-the-knee amputation. The two groups were similar in terms of their responses, but significantly more patients who had had limb salvage considered themselves severely disabled (p < 0.05). They also had more problems with the performance of occupational and recreational activities (p < 0.05). This study confirmed the reliability of modern microvascular free tissue techniques for the coverage of large soft-tissue defects associated with tibial fractures. It also showed that complications and difficulties in the restoration of osseous union are common and may be directly related to the less satisfactory functional, occupational, recreational, and quality-of-life outcomes that are seen in many patients who have had limb salvage.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

Diffuse and localized tenosynovial giant cell tumor and pigmented villonodular synovitis: a clinicopathologic and flow cytometric DNA analysis.

The DNA content and proliferative indexes of seven cases of tenosynovial giant cell tumor of tendon sheath, diffuse type (TGCT-D); 11 cases of tenosynovial giant cell tumor of tendon sheath, localized type (TGCT-L); and seven cases of pigmented villonodular synovitis (PVNS) were analyzed by flow cytometry in an attempt to assess objectively their biologic differences. Three cases of TGCT-D manifested an aneuploid DNA content and four had a diploid DNA pattern. All cases of TGCT-L and PVNS showed a diploid DNA content. The proliferative indexes for TGCT-D were significantly higher than those found in the other two groups. There was no histopathologic feature that correlated with the aneuploid DNA pattern found in two of the three cases of TGCT-D. Only one of the three aneuploid DNA content TGCT-D cases displayed marked cellular pleomorphism with dense fibrous stroma; in that case there was recurrence 4 years after initial excision. Our data further support that TGCT-D, TGCT-L, and PVNS are histopathologically similar but clinically distinct lesions. The high proliferative indexes of TGCT-D may reflect a rapid, uncontrolled growth that may explain its aggressive biologic behavior. The presence of an aneuploid DNA pattern in some cases of TGCT-D in this study, coupled with the reported chromosomal abnormalities and occurrence of malignant transformation in these lesions, clearly supports their neoplastic nature.

Adult↗
PubMed1992

Imaging rounds. Multifocal adamantinoma of the tibia and fibula.

The following is a description of the clinical and roentgenographic findings in a case exhibiting a condition of interest to the orthopaedic surgeon. Initial history, physical findings, and roentgenographic examinations are found on this page. The diagnosis and discussion of this case are presented on the following pages.

Adult↗
PubMed1991

Noninvasive grading of musculoskeletal tumors using PET.

Twenty-five patients with mass lesions involving the musculoskeletal system were studied with positron emission tomography (PET) in order to determine if a relationship exists between histologic grade and tumor uptake of [fluorine-18]2-deoxy-2-fluoro-D-glucose (FDG). There were 6 benign lesions and 19 malignant lesions of various grades. A high correlation (Rho = 0.83) was found between the normalized uptake of tracer and the NCl grade. The high-grade malignancies had significantly greater (p = 0.0091) uptake of FDG than the combination of benign lesions and low-grade malignancies. All lesions with a normalized uptake value of 1.6 or greater were high-grade, while all lesions less than 1.6 represented either benign tumors or low grade malignancies. This strong relationship between FDG uptake and grade among neoplasms from a wide variety of cell types within a single organ system suggests that the technique may be useful in predicting grade even when the cell type is unknown.

Bone Neoplasms↗
PubMed1989

Unicameral bone cyst (simple bone cyst).

A simplified treatment outline reflecting a conservative, nonoperative intervention approach for the management of simple bone cysts is presented. Included are a discussion of the etiology of these lesions and several case studies.

Adolescent↗
PubMed1988

Intramedullary osteosclerosis. A report of the clinicopathologic features of five cases.

The clinicopathologic features of five patients with intramedullary osteosclerosis are presented. The patients, ranging in age from 8 to 52 years (mean 31 years), all presented with pain referred to the lower extremity. The sclerotic lesions involved the entire lower extremity in 1 patient, mid-tibial shaft in 2, distal tibia in 1, and distal fibula in 1 patient. The histopathologic features of intramedullary osteosclerosis overlap with those of melorheostosis. The differential diagnosis also includes a spectrum of entities, each characterized by osteosclerosis and each of which is compared and contrasted to the cases presented.

Adolescent↗
PubMed1986

Competitive inhibitors of rabbit hepatic microsomal steroid 12 alpha-hydroxylase.

The sterols 7 alpha-hydroxycholest-4-en-3-one (I) and 5 alpha-cholestane-3 alpha,7 alpha-diol (II) are competitive inhibitors for rabbit hepatic microsomal preparations of steroid 12 alpha-hydroxylase with apparent Ki values of 56 and 93 microM, respectively. To ascertain the optimum structure for a substrate with maximal enzymic activity, nine sterols or steroidal acids containing the 7 alpha-hydroxy-4-en-3-one or 3 alpha,7 alpha-dihydroxy-5 alpha configuration were prepared and studied as inhibitors with enzyme preparations in the presence of NADPH, oxygen and appropriate cofactors. Although each of these compounds exhibited competitive inhibition, the best inhibitor for sterol (I) was 7 alpha,25-dihydroxycholest-4-en-3-one (IV) (Ki 36 microM). Steroidal acids (3-oxo-7 alpha-hydroxychol-4-enoic acid and 3-oxo-7 alpha-hydroxy-4-cholene-24-carboxylic acid) were poor inhibitors (Ki 1080 and 654 microM, respectively). For sterol (II) the best inhibitors were sterol (IV) (Ki 35 microM) and 5 alpha-cholestane-3 alpha,7 alpha,25-triol (VIII) (Ki 45 microM). The 12 alpha-hydroxylated products of sterols (I) and (IV) were less tightly bound to the enzyme (Ki 88 and 98 microM, respectively) in the presence of sterol (II). Allochenodeoxycholic acid (Ki 495 microM) was not a good inhibitor for sterol (II). 12 alpha-Hydroxylated products of sterols (IV) and (VIII) were isolated from larger scale incubations, separated by HPLC and identified by mass spectrometry.

Animals↗
PubMed1985

McKeever metallic hemiarthroplasty of the knee in unicompartmental degenerative arthritis. Long-term clinical follow-up and current indications.

Forty patients with forty-four unicompartmental McKeever metallic uncemented hemiarthroplasties were followed for five to thirteen years (average, eight years). Thirty-nine knees had a medial and five, a lateral arthroplasty. The age at surgery ranged from thirty-two to eight-two years (average, sixty-seven years). At the final follow-up, 70 per cent of the knees were rated as good or excellent. Seventy-nine per cent of the knees in patients who were less than sixty-five years old at the time of surgery were in these categories. Six knees (14 per cent) had required revision to either a unicompartmental or a bicompartmental total knee replacement. The average preoperative and postoperative knee flexion did not change, but knees with initially poor motion improved. The average preoperative flexion contracture of 10 degrees improved postoperatively to 5 degrees. Complications were rare and no cases of infection, peroneal palsy, or clinically detectable phlebitis occurred. Obesity did not seem to adversely affect the outcome. This study indicated that the McKeever unicompartmental metallic hemiarthroplasty can provide an attractive alternative in the treatment of unicompartmental degenerative arthritis when proximal tibial osteotomy is contraindicated or has failed or when the patient is too young, heavy, or active to consider total knee replacement.

Adult↗
PubMed1984

Ewing's sarcoma in female siblings. A clinical report and review of the literature.

The third reported case of Ewing's sarcoma in siblings is presented. All reported siblings to date have been female. Because of the most unusual occurrence, clues for environmental and genetic factors in the origin of the tumors were sought. Human leukocyte antigen (HL-A) genotyping, routine chromosomal, and prophase chromosomal studies were obtained. Despite extensive study, the existence of an infectious agent, exposure to a carcinogen, or genetic abnormality could not be defined.

Adult↗
PubMed1984

Bile acids. LXXIII. Synthesis of analogs of 7 alpha-hydroxy-4-cholesten-3-one as substrates for hepatic steroid 12 alpha-hydroxylase.

Analogs of 7 alpha-hydroxy-4-cholesten-3-one were prepared to ascertain structural features necessary for maximal activity of hepatic microsomal 12 alpha-steroid hydroxylase. Methyl 3 alpha,7 alpha-dihydroxy-5 beta-cholane-24-carboxylate derived from chenodeoxycholic acid was oxidized at C-3 with silver carbonate/Celite. The product was hydrolyzed and dehydrogenated with SeO2 to provide 3-oxo-7 alpha-hydroxy-4-cholene-24-carboxylic acid. 5 beta-Cholestane-3 alpha,7 alpha,25-triol and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol were similarly oxidized at C-3 and dehydrogenated to provide 7 alpha,25-dihydroxy-4-cholesten-3-one and 7 alpha,12 alpha,25-trihydroxy-4-cholesten-3-one, respectively. The products were characterized by thin-layer and gas chromatography, ultraviolet, infrared, proton resonance and mass spectrometry.

Animals↗