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Biomedical subjects

B C Parker

Publications and source records attributed to B C Parker.

At least 19 recordsLinked to original sources
PubMed2001

Periprosthetic bone mineral density changes with femoral components of differing design philosophy.

We measured the bone mineral density in 22 patients with the cylindrical stemmed cobalt-chrome AML prosthesis (collared) and in 22 patients with the tapered stem titanium CLS prosthesis (collarless). DEXA scanning was undertaken at a mean of 40 months in the AML and 52 months in the CLS group from the time of implant insertion. In both groups the greatest mean loss of BMD was found in Gruen zone 7 and the least change in Gruen zone 5. In all zones the BMD loss was greater in the AML group but only statistically significant in zones 6 (P<0.05) and 7 (P<0.01). Although numerous factors affect BMD changes around cementless implants, this study suggests that less bone loss can be associated with the titanium CLS stem.

Absorptiometry, Photon↗
PubMed1999

Migration of the uncemented CLS acetabular component.

The migration of uncemented press-fit CLS (Cementless Total Hip Replacement System) acetabular cups was measured retrospectively from standard anteroposterior pelvic radiographs using a digitizer and software specifically developed for this study. A radiographic and clinical review also were undertaken. There were 96 patients in the study group. The mean follow-up for radiographic review was 2.23 years, and the mean follow-up for clinical review was 3 years. Migration was measured in the cranial and medial directions. Mean migration of the cup at 2 years was 1.35 mm in the cranial direction and 2.15 mm in the medial direction. Radiographic appearances altered little over the study period. Fifty-five (57.3%) patients demonstrated bone ingrowth onto the prosthesis, predominantly in DeLee and Charnley zone 1. Twenty-one patients demonstrated nonprogressive sclerotic lines; no lucent lines were encountered. Statistical analysis showed a significant correlation between acetabular ingrowth and reduced cup migration in the medial direction (P = .011 at 5 years). There was no statistical relationship between migration of the cup and radiographic features or clinical outcome.

Acetabulum↗
PubMed1999

Migration of the uncemented CLS femoral component.

The migration of uncemented CLS (Cementless Total Hip Replacement System) femoral stems was measured retrospectively from standard anteroposterior pelvic radiographs using a digitizer and software specifically designed for this study. The study population was comprised of 117 patients with 126 uncemented CLS femoral stems. All radiographs were reviewed and the incidence of thigh pain obtained by means of a questionnaire. The mean clinical follow-up was 3 years and the mean follow-up for radiographic review was 2.77 years. The mean femoral stem migration was 2 mm at 2 years and 3.66 mm at 7 years. Radiographic features varied little with no specific predictive features in patients with excessive early migration or those who complained of thigh pain. There was no statistical relationship between the presence of thigh pain and femoral stem migration.

Adult↗
PubMed1992

Complications associated with the use of the gamma nail.

At Kingston Hospital, the Gamma nail has only been used for the fixation of unstable intertrochanteric and subtrochanteric fractures of the femur. There have been 28 cases; 21 required distal locking. Of these, there were intraoperative difficulties in nine.

Adult↗
PubMed1992

Epidemiology of infection by nontuberculous mycobacteria. Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum in acid, brown-water swamps of the southeastern United States and their association with environmental variables.

Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum (MAIS) organisms were isolated and identified from waters, soils, aerosols, and droplets ejected from water collected from four geographically separate aquatic environments (Okefenokee Swamp, GA; Dismal Swamp, VA; Claytor Lake, VA; and Cranberry Glades, WV) during several seasons. Recovery of MAIS was significantly higher from waters, soils, and aerosols collected from the two acid, brown-water swamps located in the southeastern coastal plain. High MAIS numbers correlated with warmer temperature, low pH, low dissolved oxygen, high soluble zinc, high humic acid, and high fulvic acid. This research, in relation to previous findings for the geographic distribution and physiologic ecology of MAIS, supports the conclusion that waters, soils, and aerosols of the acid, brown-water swamps of the southeastern United States coastal plain represent major environmental sources likely connected with the higher incidence of human infection in this region.

Georgia↗
PubMed1992

Current status and extended applications of intravascular stents.

The introduction of several novel techniques and mechanical devices to interventional radiology has expanded the range of therapies for a variety of medical disorders. Intravascular metallic stents have received widespread acclaim and may possess the most potential of all the newest devices available to the interventionist. The addition of metallic stents to the percutaneous therapeutic arsenal provides the interventionist with a device that can resist the elastic recoil of a stenotic vessel or support a newly created vascular tract. Peripheral artery metallic stent placement holds great promise for the treatment of selected patients; other applications of stents, including transjugular intrahepatic portosystemic stent shunts are likely to have a great impact in patient management. We review the techniques, appropriate indications, and recent clinical results of vascular stents for percutaneous intervention and therapy.

Angiography↗
PubMed1990

Unusual bony lesions of histiocytosis X in a patient previously treated for Hodgkin's disease.

We present an unusual case of multifocal Histiocytosis X in a 78-year-old man treated for Hodgkin's Disease 33 and 24 years previously. The Hodgkin's Disease at first involved cervical nodes and 9 years later axillary and inguinal nodes and was treated by radiotherapy. Chronic destructive lesions developed in the femora and pelvis and bone biopsies showed a curious mixture of fibroblastic tissue and foamy macrophages. These lesions eventually resulted in pathological fractures of the femoral necks, and bilateral hip replacements were required seven years after initial detection of the bony lesions. There was a focal infiltrate of S-100 protein positive histiocytic cells containing Birbeck granules in the femoral heads. There was radioisotopic and radiological evidence of other skeletal lesions. The association between Histiocytosis X and Hodgkin's Disease is recognised but rare and its significance is discussed.

Adult↗
PubMed1989

Epidemiology of infection by nontuberculous mycobacteria. VIII. Absence of mycobacteria in chicken litter.

Overlap in the geographic distributions of (1) higher frequencies of persons reacting to antigens prepared from the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) group; (2) higher frequencies of isolation from natural waters and soils; (3) higher densities of farms producing broilers (chicken) in the southeastern United States raises the question of whether MAIS organisms occur abundantly in chicken litter (pine bark shavings containing avian fecal material) and whether litter may be a potential source of animal or human infection through its subsequent use as a fertilizer or feed supplement. We show here that potentially pathogenic mycobacteria were seldom recovered from chicken litter containing avian fecal material. Further, litter appears bactericidal to these organisms in that less than 1% of cells inoculated survived more than 6 wk, probably because of the high pH of litters.

Animal Feed↗
PubMed1987

Epidemiology of infection by nontuberculous mycobacteria. VII. Absence of mycobacteria in southeastern groundwaters.

Using the fluorochrome auramine-O, direct microscopic counts of log phase cells of Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) group showed excellent correlations with viable spread-plate counts. Accordingly, an enumeration of total acid-fast and MAIS cells by stain and culture (respectively) in groundwaters from three United States regions that differ in their incidence of human infection by MAIS was undertaken. Of 30 state-monitored, undisinfected wells, 11 were in Georgia coastal plain (high incidence), 10 were in the Virginia coastal plain (intermediate incidence), and 9 were in Montgomery County, Virginia (low incidence). Total acid-fast cells ranged widely between 280 to 5,367 per ml among the groundwaters, and with one exception showed no correlations or trends between regions of different incidence of human infection, or to total bacterial cell counts or colony-forming units. The exception was that the proportions of acid-fast cells relative to total cells were higher in the Georgia groundwaters. However, despite the relatively high auramine-O counts, few mycobacteria were recovered by culture. Of 12 wells yielding mycobacteria, 9 yielded rapidly growing and 4 slowly growing mycobacteria. Only one well in Montgomery County, Virginia (region of low incidence) yielded a MAIS isolate, albeit at low density. This research supports the conclusion that clean groundwaters are unlikely sources of MAIS infection in humans in the southeastern United States.

Georgia↗
PubMed1986

Oxygen budget of a perennially ice-covered Antarctic lake.

A bulk O2 budget for Lake Hoare, Antarctica, is presented. Five years of seasonal data show the lake to be persistently supersaturated with O2. Oxygen is carried into the lake in glacial meltstreams and is left behind when this water is removed as ice by ablation and sublimation. A diffusive loss of O2 from the lake through the summer moat is suggested. Measured values of the total O2 in the water column indicate that the time scale of O2 turnover is much longer than a year. Based on these results we suggest that the amount of O2 in the water does not change significantly throughout the year and that the lake is also supersaturated with N2.

Antarctic Regions↗
PubMed1985

Cryoconite holes on glaciers.

Cryoconite holes are water-filled depressions on the surface of glaciers. They contain microbial communities and may contribute to glacial wastage and biological colonization of ice-free areas.

Antarctic Regions↗