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Biomedical subjects

R L Miller

Publications and source records attributed to R L Miller.

At least 127 records · Page 7Linked to original sources
PubMed1989

A radioimmunoassay for physostigmine in biological fluids and tissues.

Antibodies were produced in rabbits immunized with physostigmine conjugated to bovine serum albumin (BSA) by two different methods: a diazo immunogen coupled to BSA with carbodiimide and a Mannich coupled immunogen. Both immunogens produced antibodies that could be used to develop sensitive and specific radioimmunoassays (RIA) for physostigmine. The limit of detection of the RIA is 100 pg of physostigmine in plasma or tissue homogenates (1.0 ng ml-1), without the need for an extraction procedure. The interassay and intraassay coefficients of variation were less than 13% in the RIA. No appreciable binding was observed between the antibodies and physostigmine metabolites or other drugs commonly used with physostigmine. The specificity of the RIA was further validated by measuring physostigmine concentrations in biological samples in tandem with high-pressure liquid chromatography. The RIA was used to study the time course of plasma concentrations and tissue distribution of physostigmine in rats.

4-Aminobenzoic Acid↗
PubMed1989

A second survey of graduates of a traditionally black college of medicine.

To update and expand upon its 1975-76 survey of 729 graduates of seven classes, Howard University College of Medicine (HUCM) conducted a longer survey in 1985-86 of 1,985 graduates spanning 49 classes. Replies of the 728 respondents to the second survey confirm that HUCM's predominantly black alumni were continuing to provide patient care to a substantial number of poor blacks in urban areas. Fifty-six percent of all HUCM alumni were in primary care, compared with 46% of all alumni of U.S. medical schools who were in primary care. New findings included concerns about malpractice suits and physician impairment. Regarding physician supply in their own communities, 53% of respondents believed that there were too many physicians overall, but 63% believed there were too few black physicians. For the 1940-1969 graduates, loans financed 10% of their medical education, and indebtedness influenced the types of practice chosen by 4%; comparable figures for the 1970-1980 graduates were 25% and 11%.

Black or African American↗
PubMed1989

Cyclosporine augments renal mitochondrial function in vivo and reduces renal blood flow.

The in vivo action of cyclosporine A (CS) on rat renal cortical mitochondria was investigated. CS (30 mg.kg-1.day-1) given orally to rats for 30 days caused an augmentation of renal mitochondrial oxidative phosphorylation. The ADP-stimulated respiratory rate was increased by 37.0% with glutamate plus malate as respiratory substrates (P less than 0.025) but not with succinate-supported respiration, indicating enhancement of mitochondrial complex I activity. This reaction may be a response to the 32.5% reduction of renal blood (P less than 0.005) in the CS-treated group, possibly serving to maximize ATP synthesis during ischemia. Ligation-induced decreases in renal blood flow also resulted in enhancement of mitochondrial complex I activity.

Animals↗
PubMed1989

Death in the nursing home: senescence, infection and other causes.

1. Clinical reasons for death in a skilled nursing home continue to show infectious causes as the leading etiology. 2. The concept of senescence is probably overlooked as a legitimate explanation for death in elderly patients. Senescence can be defined as a protracted and progressive decline of multiple body functions not attributable to one specific etiology and culminating in the patient's death. 3. The majority of deaths occurred within the first year after admission to the skilled nursing home setting. 4. The majority of deaths among the patients in this study occurred in the nursing home setting, not the hospital.

Aged↗
PubMed1989

Pulmonary diffusing capacity as a predictor of performance in competitive swimming.

Pulmonary diffusing capacity has been noted by many investigators to be higher in championship swimmers than in average swimmers and in the non-swimming population. We measured pulmonary diffusing capacity (DLCO) and other parameters in 22 members of a collegiate swimming team and studied the relationship between pulmonary diffusing capacity and swimming performance. We also investigated change in lung function over a season of training and racing. Results suggested that while most good swimmers had above average diffusing capacities, there was no statistically significant difference in performance between those swimmers with high DLCO (greater than or equal to 110% predicted value) and those with a low DLCO (less than 100% predicted value). It was also determined that there was not a good correlation between performance (measured by either "best time" or "average time") and lung function (DLCO or VC).

Adolescent↗
PubMed1988

In vitro characterization and biomechanical optimization of a biodegradable particulate composite bone cement.

We have developed a biodegradable particulate composite bone cement and used in vitro and in vivo methods for studying its suitability for orthopaedic applications. The composite matrix consists of gelatin, water, and sodium salicylate. The particulate phase is made up of powdered and particulate (355-600 microns diameter) tricalcium phosphate. Paraformaldehyde (0.1% to 0.5% by weight) is used as a matrix cross-linking agent. The effects of incubation time, particulate volume fraction, density of the individual particles, water content, concentration of crosslinking agent, and freeze-drying on the unconfined compressive strength and modulus of the particulate composite were measured. Compressive strengths of 7 MPa and moduli of 65 MPa could be achieved. Mechanical properties depended critically upon the water content of the particulate composite, with values of strength and modulus decreasing rapidly outside a range of 10-14% of specimen dry weight. High-density tricalcium phosphate particulate produced cement with twice the strength found with porous particulate. In a companion study we document in vivo performance of this particulate composite in an animal model system.

Biocompatible Materials↗
PubMed1988

Antibiotic release from an experimental biodegradable bone cement.

An experimental biodegradable bone cement [poly(propylene fumarate)-methylmethacrylate] (PPF-MMA) has been compared in vivo with polymethylmethacrylate (PMMA) as a carrier agent for local release of antibiotics. This approach is potentially applicable to the treatment of chronic osteomyelitis where the clinical goal is to achieve sustained high concentrations of antibiotics locally in the infected bone. In our experiments, gentamicin- and vancomycin-impregnated cylindrical PMMA and PPF-MMA cement specimens were implanted subcutaneously in rats, and blood and wound fluid samples were obtained over a 2-week period. Antibiotic levels were determined using immunoassays, and microbiologic activity was confirmed with agar diffusion techniques. The biodegradable PPF-MMA cement achieved and maintained considerably higher wound antibiotic levels than did PMMA cement. Vancomycin levels for the PPF-MMA cement were greater than 20 times those for the PMMA cement at all sampling times from 24 h to 14 days. For both cements, the serum antibiotic concentrations remained safely below maximum levels recommended for parenteral therapy. Mechanical testing of the PPF-MMA cement showed that admixture of 3% by weight of antibiotic did not adversely affect material properties. We conclude that this experimental biodegradable bone cement (PPF-MMA) can be used as a carrier to achieve high sustained local levels and low serum levels of antibiotics. Because it is biodegradable and thus does not require a secondary procedure for removal, it has special potential for use in treatment of chronic osteomyelitis.

Administration, Topical↗
PubMed1988

Phase II evaluation of sequential hepatic artery infusion of 5-fluorouracil and hepatic irradiation in metastatic colorectal carcinoma.

Twenty-seven patients with measurable liver metastases from colorectal carcinoma were entered on a protocol of intermittent hepatic artery infusion (HAI) of 5-fluorouracil (5-FU) followed by consolidation with hepatic irradiation. Five partial responses were observed in 23 evaluable patients. Median duration of response was 3.5 months. A response was evident after chemotherapy alone in four of five responders. Hepatic irradiation converted one patient with stable disease after chemotherapy to a partial responder. Median survival for all patients was 9.0 months (range 1.5-34.0). Combined modality treatment with HAI of 5-FU followed hepatic irradiation was well tolerated but did not appear to be synergistic.

Colonic Neoplasms↗
PubMed1988

Identification of Giardia lamblia isolates susceptible and resistant to infection by the double-stranded RNA virus.

The presence or absence of the Giardia lamblia double-stranded RNA virus (GLV) was surveyed among 38 axenic isolates of G. lamblia derived from both humans and animals. Of the 28 isolates lacking the virus, 19 could readily be infected by the virus. The remaining 9 isolates proved to be resistant to GLV infection even when the ratio between virus to parasite reached as high as 10(6) to 1. Evidence is also presented indicating that there are at least two "Portland 1" strains being used by the current scientific community, one containing the virus and the other lacking the virus.

Animals↗
PubMed1988

Evaluation of a digitizer and computer system designed to analyze articulator-generated occlusal tracings.

Occlusal tracings generated on a Denar fully adjustable articulator were photographed, projected, digitized, and stored in a computer data file. These steps were accomplished with sufficient accuracy for clinical analysis. This study demonstrated that appropriately referenced tracing data can be transferred accurately into a machine-readable form. Studies of pantographic tracings for mandibular movements are facilitated by this convenient and accurate method of handling data.

Dental Articulators↗
PubMed1988

Purification and characterization of the Giardia lamblia double-stranded RNA virus.

The dsRNA virus which infects some strains of Giardia lamblia has been purified and characterized with respect to its effect on growth of the parasite. Extensive purification of the virus from G. lamblia growth medium was accomplished by Millipore filtration and two successive CsCl gradient centrifugations. The purified virus possessed a single major protein species of 100,000 molecular weight. Effects of the extensively purified virus on growth of the virus-free parasite were studied. A cloned WB strain, sensitive to the viral infection, and a cloned E-9/M strain, resistant to the infection, were studied. With the WB strain, infection can occur at a ratio as low as 10 viral particles per organism. As the virus to parasite ratio increased, the rate of growth of the parasite decreased and the percentage of parasites not adhering to the culture tube wall also increased. These nonadhering cells, which differed from the nonadhering cells under normal growth conditions, were unable to divide. They contained an average number of 500,000 viral particles per cell which may be the threshold intracellular density of viral particles arresting the growth of G. lamblia. The results also suggest that the specific consequence of viral infection, even at extremely high multiplicity of infection, is not lysis of G. lamblia trophozoites but cessation of growth.

Animals↗