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Biomedical subjects

K L Brown

Publications and source records attributed to K L Brown.

At least 91 records · Page 5Linked to original sources
PubMed1987

Bone ingrowth into polymer coated porous synthetic coralline hydroxyapatite.

Porous hydroxyapatite, converted hydrothermally from the calcium carbon exoskeleton of the coral genus Goniopora (CHAG), has been shown to be effective as a scaffold for bone ingrowth (2,3,5-7,9). However, the large pores in the material resulted in low compressive strengths. In a previous study, we found that microcoating the internal surfaces of CHAG with dilactic-polyactic acid (DL-PLA) improved significantly its compressive properties. The objective of this study was to determine the effect of PLA microcoating on bone ingrowth into CHAG plugs. Plugs of thick- (3:1 chloroform to DL-PLA by weight), medium- (10:1), and thin- (30:1) coated as well as uncoated CHAG were implanted transcortically in the proximal third of the diaphysis of the rabbit tibia. Specimens were harvested at 3, 12, and 24 weeks for mechanical testing and contralaterally for histological and histomorphometric assessment. At 12 weeks, uncoated CHAG plugs developed an average ultimate interface shear stress of 26.7 MPa, compared with 17 MPa for 30:1 and 8 MPa for 10:1 and 3:1 coated specimens. At 24 weeks, there were no significant differences in shear stress among any of the specimens. Histomorphometric assessments showed that the ratio of area fractions of new bone to area fractions of new bone and void space increased from 68-70% for 3:1 and 10:1 coated specimens at 3 weeks, and to 85.5-89.5% at 24 weeks. In comparison, uncoated and 30:1 specimens had area fraction ratios of about 82% at 3 weeks and 93% at 24 weeks. Histologic sections demonstrated direct apposition of new bone to both the coating and the hydroxyapatite as well as degradation of the coating.

Animals↗
PubMed1987

Noninvasive evaluation of mineral content of bone without use of ionizing radiation.

The mineral content of bone can be quantified by recording a 31P NMR spectrum while the bone is stationary. The quantity of mineral in the bone is determined from the spectrum with a reference standard by comparison of relative peak areas. The phosphate of bone mineral is readily distinguished from inorganic phosphate and phosphorylated metabolites dissolved in cytosol and from the head groups of phospholipids in membranes. The technical feasibility of constructing a cost-effective instrument for analysis of bone mineral content in the extremities is demonstrated. The possible utility of such a noninvasive assay for detecting osteoporosis and for monitoring the progress of treatment is discussed.

Bone and Bones↗
PubMed1987

Alveolar rhabdomyosarcoma of the larynx: case report and literature review.

We report the 11th well-documented case of laryngeal rhabdomyosarcoma and only the second of laryngeal alveolar rhabdomyosarcoma. The optimum treatment of head and neck rhabdomyosarcoma has not yet been defined, but it appears that the ideal should consist of an aggressive multimodality approach. This includes surgical extirpation if it can be done without major morbidity, postoperative radiotherapy with a margin around known and suspected disease, and multiagent chemotherapy. Unlike most sarcomas, rhabdomyosarcoma (especially alveolar rhabdomyosarcoma) spreads by way of the lymphatic system as well as the blood stream. Inclusion of the draining lymphatics in the radiation field must be given strong consideration.

Combined Modality Therapy↗
PubMed1985

Compressive properties of polymer coated synthetic hydroxyapatite for bone grafting.

A porous hydroxyapatite material hydrothermally converted from the calcium carbonate exoskeleton of the coral, genus Goniopora (CHAG) was either microcoated using polymethylmethacrylate (PMMA) or polylactic acid (PLA) to cover all internal surfaces, or externally coated to produce a shell, with the objective of reducing the brittleness of the material. Compressive testing showed that while CHAG, externally coated with PMMA, showed the largest increases in strength, stiffness, and energy absorption, the uncoated hydroxyapatite core cracked at low loads although the shell remained intact. CHAG internally microcoated with PMMA showed a 3.84 increase in compressive strength while specimens with internal PLA coatings had 1.81 times the compressive strength of uncoated CHAG specimens. Compared to the mechanical properties of cancellous graft material, specimens internally microcoated with either polymer could be produced having properties equivalent to or greater than those of cancellous graft.

Animals↗
PubMed1985

Distribution of gamma exposure rates in a reactor effluent stream flood plain system.

Ground-level gamma dosimetry surveys were conducted along the length of a radiocesium-contaminated reactor effluent stream flood plain system to determine the extent and patterns of isotope distribution over a decade after reactor releases were stopped. The maximum mean exposure rates were found at upstream locations near the source of the contamination and in a downstream sedimentary delta. Gamma exposure rates were not uniformly distributed and high exposure rates were generally restricted to small areas of the flood plain. There was little similarity in either the spatial distribution or magnitudes of maximum gamma exposure rates across flood plains along the stream. Frequency the measured exposure rates tended to be highly skewed and most closely approximated the log-normal distribution in most areas along the stream. However, the complex and changing patterns of dose distributions strongly affected the ability to predict the probability of encountering unusually high exposure rates. Complex statistical and distributional models are required to provide precise descriptions of the dosimetry environment in such complex ecosystems and different models could be required on a site-by-site basis.

Cesium Radioisotopes↗
PubMed1985

Rapid diagnosis of LaCrosse encephalitis: detection of specific immunoglobulin M in cerebrospinal fluid.

An immunoglobulin M (IgM) antibody capture enzyme immunoassay (MAC-EIA) was developed for the rapid and early diagnosis of LaCrosse (LAC) virus infections. The MAC-EIA was a sensitive and specific technique for the detection of IgM antibodies to LAC virus in cerebrospinal fluid specimens and in acute-phase serum specimens. In a retrospective study, cerebrospinal fluid and acute-phase serum paired samples from 108 patients were tested by the MAC-EIA and by an IgM immunofluorescence assay. The results were compared with the original diagnosis, which was made by using a variety of classical serological tests including serum neutralization, hemagglutination inhibition, and complement fixation. Thirty patients were confirmed as having LAC virus infections; of these, 30 (100%) were diagnosed as positive by serum MAC-EIA, and 27 (90%) were positive by cerebrospinal fluid MAC-EIA. The MAC-EIA was more sensitive than the IgM immunofluorescence assay. Two patients who were not previously confirmed as positive cases were diagnosed as having LAC virus infections by the MAC-EIA. One patient who was subsequently diagnosed as having a Jamestown Canyon virus infection and two patients who were previously infected with Jamestown Canyon virus were not falsely identified as having LAC virus infections by the MAC-EIA.

Antibodies, Viral↗
PubMed1985

Population-based occupational cancer incidence surveillance. Utilization of the telephone interview.

Because population-based surveillance of cancer incidence across a wide variety of industries and occupations is quite rare and because the vast literature in occupational cancer epidemiology concentrates to a great extent on cancer risks among white males, new methods are needed to generate hypotheses about occupational cancer risks. The results of a series of studies conducted during the past six years suggested that the telephone interview could be utilized as an effective method for occupational cancer surveillance. A 10-minute telephone interview that was developed to collect occupational histories, smoking histories, and other related data and some methodologic issues that were tested during a pilot study are described. The authors found the telephone interview to be an effective instrument for obtaining these data. This study suggests that it is important to obtain as high a proportion as possible of the responses from the study patients rather than proxy respondents; that when one cannot interview the patient, proxy respondents can provide much of the data requested; and that supplementing population-based cancer surveillance system data with these interview data is useful in routine monitoring.

Adult↗
PubMed1984

Computed tomography of synovial sarcoma of the foot.

We report two patients with synovial sarcoma of the foot. Both presented with a soft-tissue mass that exhibited calcification. Although the radiologic findings are non-specific, the presence of foci of calcification within the soft-tissue mass is suggestive of synovial sarcoma. Computed tomography shows the extent of the mass, soft-tissue calcification and bone destruction thus helping in earlier detection and more accurate staging.

Calcinosis↗
PubMed1984

Review of obstetrical palsies. Nonoperative treatment.

For the majority of patients with obstetrical brachial plexus palsy, present-day conservative management yields good results. We now must direct our efforts toward improving the 10 to 15 per cent of patients who do not do well. Presently the role of microsurgical reconstruction of these injuries is undergoing evaluation. We must identify the patients with poor prognosis early: Babies should be examined at monthly intervals to document functional return, to supervise the child's exercise program, and to provide parental support. Babies who do not improve rapidly within the first 2 to 3 months should have an electromyogram and nerve conduction study. If this shows evidence of a severe lesion, these patients should be referred to a physician with a special interest in this area.

Arm↗
PubMed1982

Indirect fluorescent-antibody technique for serological diagnosis of La Crosse (California) virus infections.

A clinically relevant indirect fluorescent-antibody technique (IFA) was developed for the serological diagnosis of La Crosse virus infections. The IFA (67%) was as sensitive as the hemagglutination inhibition (58%) and neutralization (58%) tests in the detection of antibodies in acute-phase specimens. Immunoglobulin M antibodies were detected by the IFA test in 48% (11 of 23) of these specimens. Diagnostically significant increases in IFA titer were detected in 86% (19 of 22) of the paired samples. Antibodies were detectable in some patients 7 years after infection; however, the IFA test was not as sensitive as the other two tests in the detection of previous infections.

Child↗
PubMed1982

Capture immunoglobulin M system for rapid diagnosis of La Crosse (California encephalitis) virus infections.

A capture immunoglobulin M (IgM) enzyme immunoassay was developed to diagnose La Crosse virus infections by the detection of specific IgM in acutephase serum specimens. IgM was detected by the capture IgM system in the serum of 24 of 29 (83%) of the patients studied. In comparison, IgM was detected in 19 of 29 (66%) of the patients by an indirect immunofluorescence technique. Specific IgM was detected in 83% (20 of 24) of patient serum specimens by day 3 after the onset of clinical symptoms.

Encephalitis, Arbovirus↗